97 results on '"Intermediate complexity"'
Search Results
2. Lack of bipolar see-saw in response to Southern Ocean wind reduction
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Levermann, A., Schewe, J., Montoya Redondo, María Luisa, Levermann, A., Schewe, J., and Montoya Redondo, María Luisa
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© 2007 by the American Geophysical Union. We are grateful to J. R. Toggweiler and J. Mignot for useful comments on the manuscript. A.L. was funded by the Gary Comer foundation, M.M. by the Ramón y Cajal Program and project CGL2005-06097/CLI of the Spanish Ministry for Science and Education., A cessation of the Atlantic meridional overturning circulation (AMOC) significantly reduces northward oceanic heat transport. In response to anomalous freshwater flux, this leads to the classic 'bipolar see-saw' pattern of northern cooling and southern warming in surface air and ocean temperatures. By contrast, as shown here in a coupled climate model, both northern and southern cooling are observed for an AMOC reduction in response to reduced wind stress in the Southern Ocean (SO). For very weak SO wind stress, not only the overturning circulation collapses, but sea ice export from the SO is strongly reduced. Consequently, sea ice extent and albedo increase in this region. The resulting cooling overcompensates the warming by the reduced northward heat transport. The effect depends continuously on changes in wind stress and is reversed for increased winds. It may have consequences for abrupt climate change, the last deglaciation and climate sensitivity to increasing atmospheric CO_2 concentration., Comer Family Foundation, Ayudas para contratos Ramón y Cajal (RYC), Ministerio de Educación y Ciencia (MEC), España, Ministerio de Economía y Competitividad (MINECO), España, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub
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- 2023
3. Simulation of the cold climate event 8200 years ago by meltwater outburst from Lake Agassiz
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Bauer, E., Ganopolski, A., Montoya Redondo, María Luisa, Bauer, E., Ganopolski, A., and Montoya Redondo, María Luisa
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© 2004 by the American Geophysical Union. This work was supported by the Research Grant 01 LG 9906 of BMBF. The work benefited from discussions with Reinhard Calov, Stefan Rahmstorf, and Sushma Prasad. The time series from GRIP and NorthGRIP were kindly provided by Sigfus Johnsen. The authors thank Hans Renssen and the anonymous Referee for their valuable comments on the manuscript., The cold climate anomaly about 8200 years ago is investigated with CLIMBER-2, a coupled atmosphere-ocean-biosphere model of intermediate complexity. This climate model simulates a cooling of about 3.6 K over the North Atlantic induced by a meltwater pulse from Lake Agassiz routed through the Hudson strait. The meltwater pulse is assumed to have a volume of 1.6 x 10^14 m^3 and a period of discharge of 2 years on the basis of glaciological modeling of the decay of the Laurentide Ice Sheet ( LIS). We present a possible mechanism which can explain the centennial duration of the 8.2 ka cold event. The mechanism is related to the existence of an additional equilibrium climate state with reduced North Atlantic Deep Water (NADW) formation and a southward shift of the NADW formation area. Hints at the additional climate state were obtained from the largely varying duration of the pulse-induced cold episode in response to overlaid random freshwater fluctuations in Monte Carlo simulations. The model equilibrium state was attained by releasing a weak multicentury freshwater flux through the St. Lawrence pathway completed by the meltwater pulse. The existence of such a climate mode appears essential for reproducing climate anomalies in close agreement with paleoclimatic reconstructions of the 8.2 ka event. The results furthermore suggest that the temporal evolution of the cold event was partly a matter of chance., Webauftritts des Bundesministeriums für Bildung und Forschung (BMBF), Alemania, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub
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- 2023
4. Surface wind-stress threshold for glacial Atlantic overturning
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Montoya Redondo, María Luisa, Levermann, Anders, Montoya Redondo, María Luisa, and Levermann, Anders
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© 2008 by the American Geophysical Union. M. M. was funded by the Ramón y Cajal Program and project CGL2005-06097/CLI of the Spanish Ministry for Science and Education. We are grateful to J. R. Toggweiler for constructive criticism which has improved this manuscript., Using a coupled model of intermediate complexity the sensitivity of the last glacial maximum (LGM) Atlantic meridional overturning circulation (AMOC) to the strength of surface wind-stress is investigated. A threshold is found below which North Atlantic deep water formation (DWF) takes place south of Greenland and the AMOC is relatively weak. Above this threshold, DWF occurs north of the Greenland-Scotland ridge, leading to a vigorous AMOC. This nonlinear behavior is explained through enhanced salt transport by the wind-driven gyre circulation and the overturning itself. Both pattern and magnitude of the Nordic Sea's temperature difference between strong and weak AMOC states are consistent with those reconstructed for abrupt climate changes of the last glacial period. Our results thus point to a potentially relevant role of surface winds in these phenomena., Ayudas para contratos Ramón y Cajal (RYC), MINECO, Ministerio de Educación y Ciencia (MEC), España, Ministerio de Economía y Competitividad (MINECO), España, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub
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- 2023
5. Millennial-scale oscillations in the Southern Ocean in response to atmospheric CO2 increase
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Álvarez Solas, Jorge, Charbit, Sylvie, Ramstein, Gilles, Paillard, Didier, Dumas, Christophe, Ritz, Catherine, Roche, Didier M., Álvarez Solas, Jorge, Charbit, Sylvie, Ramstein, Gilles, Paillard, Didier, Dumas, Christophe, Ritz, Catherine, and Roche, Didier M.
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© 2010 Elsevier B.V. We are very grateful to the editor and to three anonymous referees who helped us to improve the manuscript. We also thank Masa Kageyama, Yannick Donnadieu, Marisa Montoya and Frank Pattyn for the many stimulating and fruitful discussions in the field. This work is supported by the French nationals LEFE/CASTOR and ANR/IDEGLACE projects and by the Research Training Network NICE. Didier M. Roche and Catherine Ritz are supported by INSU/CNRS., A coupled climate-ice-sheet model is used to investigate the response of climate at the millennial time scale under several global warming long-term scenarios, stabilized at different levels ranging from 2 to 7 times the pre-industrial CO2 level. The climate response is mainly analyzed in terms of changes in temperature, oceanic circulation, and ice-sheet behaviour. For the 4 x CO2 scenario, the climate response appears to be highly non-linear: abrupt transitions occur in the Southern Ocean deep water formation strength with a period of about 1200 yr. These millennial oscillations do not occur for both lower and larger CO2 levels. We show that these transitions are associated with internal oscillations of the Southern Ocean, triggered by the Antarctic freshwater budget. We first analyse the oscillatory mechanism. Secondly, through a series of 420 sensitivity experiments we also explore the range of temperature and freshwater flux for which such oscillations can be triggered., LEFE/CASTOR, ANR/IDEGLACE, Research Training Network NICE, INSU/CNRS, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub
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- 2023
6. Role of CO2 and Southern Ocean winds in glacial abrupt climate change
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Banderas Carreño, Rubén, Álvarez Solas, Jorge, Montoya, M., Banderas Carreño, Rubén, Álvarez Solas, Jorge, and Montoya, M.
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This work was funded by the Spanish Ministries for Environment (MARM) and Science and Innovation (MCINN) under the 200800050084028 and CGL08-06558-C02-01 projects. Research by J. Álvarez-Solás was also supported by a PICATA postdoctoral fellowship of the Moncloa Campus of International Excellence (UCM-UPM). The model simulations were performed at the Spanish Environmental Research Centre (CIEMAT) in Madrid. We are also grateful to the PalMA group for useful comments and suggestions as well as to G. Knorr and to three anonymous reviewers whose recommendations have contributed to improve the manuscript., The study of Greenland ice cores revealed two decades ago the abrupt character of glacial millennial-scale climate variability. Several triggering mechanisms have been proposed and confronted against growing proxy-data evidence. Although the implication of North Atlantic deep water (NADW) formation reorganisations in glacial abrupt climate change seems robust nowadays, the final cause of these reorganisations remains unclear. Here, the role of CO2 and Southern Ocean winds is investigated using a coupled model of intermediate complexity in an experimental setup designed such that the climate system resides close to a threshold found in previous studies. An initial abrupt surface air temperature (SAT) increase over the North Atlantic by 4 K in less than a decade, followed by a more gradual warming greater than 10 K on centennial timescales, is simulated in response to increasing atmospheric CO2 levels and/or enhancing southern westerlies. The simulated peak warming shows a similar pattern and amplitude over Greenland as registered in ice core records of Dansgaard-Oeschger (D/O) events. This is accompanied by a strong Atlantic meridional overturning circulation (AMOC) intensification. The AMOC strengthening is found to be caused by a northward shift of NADW formation sites into the Nordic Seas as a result of a northward retreat of the sea-ice front in response to higher temperatures. This leads to enhanced heat loss to the atmosphere as well as reduced freshwater fluxes via reduced sea-ice import into the region. In this way, a new mechanism that is consistent with proxy data is identified by which abrupt climate change can be promoted., Spanish Ministry for Environment (MARM), Spanish Ministry for Science and Innovation (MCINN), PICATA, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub
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- 2023
7. Investigating the causes of the response of the thermohaline circulation to past and future climate changes
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Montoya Redondo, María Luisa, otros, ..., Montoya Redondo, María Luisa, and otros, ...
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© 2006 American Meteorological Society. Artículo firmado por 23 autores. We wish to thank T. Delworth, M. Harrison, and J. Russell for useful comments that improved earlier versions of this manuscript. We also thank two anonymous reviewers for their reviews, and our respective funding agencies for support., The Atlantic thermohaline circulation (THC) is an important part of the earth's climate system. Previous research has shown large uncertainties in simulating future changes in this critical system. The simulated THC response to idealized freshwater perturbations and the associated climate changes have been intercompared as an activity of World Climate Research Program (WCRP) Coupled Model Intercomparison Project/Paleo-Modeling Intercomparison Project (CMIP/PMIP) committees. This intercomparison among models ranging from the earth system models of intermediate complexity (EMICs) to the fully coupled atmosphere-ocean general circulation models (AOGCMs) seeks to document and improve understanding of the causes of the wide variations in the modeled THC response. The robustness of particular simulation features has been evaluated across the model results. In response to 0.1-Sv (1 Sv equivalent to 10^6 ms^3 s^-1) freshwater input in the northern North Atlantic, the multimodel ensemble mean THC weakens by 30% after 100 yr. All models simulate sonic weakening of the THC, but no model simulates a complete shutdown of the THC. The multimodel ensemble indicates that the surface air temperature could present a complex anomaly pattern with cooling south of Greenland and warming over the Barents and Nordic Seas. The Atlantic ITCZ tends to shift southward. In response to 1.0-Sv freshwater input, the THC switches off rapidly in all model simulations. A large cooling occurs over the North Atlantic. The annual mean Atlantic ITCZ moves into the Southern Hemisphere. Models disagree in terms of the reversibility of the THC after its shutdown. In general, the EMICs and AOGCMs obtain similar THC responses and climate changes with more pronounced and sharper patterns in the AOGCMs., Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub
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- 2023
8. Changes in Local and Global Climate Feedbacks in the Absence of Interactive Clouds: Southern Ocean–Climate Interactions in Two Intermediate-Complexity Models
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Thomas F. Stocker and Patrik L. Pfister
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Atmospheric Science ,Intermediate complexity ,010504 meteorology & atmospheric sciences ,530 Physics ,13. Climate action ,Global climate ,Climatology ,Environmental science ,Oceanic climate ,010502 geochemistry & geophysics ,01 natural sciences ,0105 earth and related environmental sciences - Abstract
The global-mean climate feedback quantifies how much the climate system will warm in response to a forcing such as increased CO2 concentration. Under a constant forcing, this feedback becomes less negative (increasing) over time in comprehensive climate models, which has been attributed to increases in cloud and lapse-rate feedbacks. However, out of eight Earth system models of intermediate complexity (EMICs) not featuring interactive clouds, two also simulate such a feedback increase: Bern3D-LPX and LOVECLIM. Using these two models, we investigate the causes of the global-mean feedback increase in the absence of cloud feedbacks. In both models, the increase is predominantly driven by processes in the Southern Ocean region. In LOVECLIM, the global-mean increase is mainly due to a local longwave feedback increase in that region, which can be attributed to lapse-rate changes. It is enhanced by the slow atmospheric warming above the Southern Ocean, which is delayed due to regional ocean heat uptake. In Bern3D-LPX, this delayed regional warming is the main driver of the global-mean feedback increase. It acts on a near-constant local feedback pattern mainly determined by the sea ice–albedo feedback. The global-mean feedback increase is limited by the availability of sea ice: faster Southern Ocean sea ice melting due to either stronger forcing or higher equilibrium climate sensitivity (ECS) reduces the increase of the global mean feedback in Bern3D-LPX. In the highest-ECS simulation with 4 × CO2 forcing, the feedback even becomes more negative (decreasing) over time. This reduced ice–albedo feedback due to sea ice depletion is a plausible mechanism for a decreasing feedback also in high-forcing simulations of other models.
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- 2021
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9. The Building Blocks of Northern Hemisphere Wintertime Stationary Waves
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Moran Erez, Ian White, Chaim I. Garfinkel, Edwin P. Gerber, and Martin Jucker
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Atmospheric Science ,010504 meteorology & atmospheric sciences ,Northern Hemisphere ,Contrast (music) ,Forcing (mathematics) ,010502 geochemistry & geophysics ,01 natural sciences ,Standing wave ,Intermediate complexity ,Boreal ,13. Climate action ,Climatology ,General Circulation Model ,Geology ,0105 earth and related environmental sciences - Abstract
An intermediate-complexity moist general circulation model is used to investigate the forcing of stationary waves in the Northern Hemisphere boreal winter by land–sea contrast, horizontal heat fluxes in the ocean, and topography. The additivity of the response to these building blocks is investigated. In the Pacific sector, the stationary wave pattern is not simply the linear additive sum of the response to each forcing. In fact, over the northeast Pacific and western North America, the sum of the responses to each forcing is actually opposite to that when all three are imposed simultaneously due to nonlinear interactions among the forcings. The source of the nonlinearity is diagnosed using the zonally anomalous steady-state thermodynamic balance, and it is shown that the background-state temperature field set up by each forcing dictates the stationary wave response to the other forcings. As all three forcings considered here strongly impact the temperature field and its zonal gradients, the nonlinearity and nonadditivity in our experiments can be explained, but only in a diagnostic sense. This nonadditivity extends up to the stratosphere, and also to surface temperature, where the sum of the responses to each forcing differs from the response if all forcings are included simultaneously. Only over western Eurasia is additivity a reasonable (though not perfect) assumption; in this sector land–sea contrast is most important over Europe, while topography is most important over western Asia. In other regions, where nonadditivity is pronounced, the question of which forcing is most important is ill-posed.
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- 2020
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10. Trade‐offs and synergies in managing coastal flood risk: A case study for New York City
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Klaus Keller, Robert L. Ceres, and Chris E. Forest
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Environmental Engineering ,Flood myth ,Computer science ,business.industry ,Geography, Planning and Development ,Trade offs ,TC530-537 ,Solution set ,flood defence measures ,Disasters and engineering ,River protective works. Regulation. Flood control ,modelling ,Intermediate complexity ,Risk analysis (engineering) ,TA495 ,storm surge ,strategy ,Safety, Risk, Reliability and Quality ,Set (psychology) ,Representation (mathematics) ,Coastal flood ,business ,Risk management ,Water Science and Technology - Abstract
Decisions on how to manage future flood risks are frequently informed by both sophisticated and computationally expensive models. This complexity often limits the representation of uncertainties and the consideration of strategies. Here we use an intermediate complexity model framework that enables us to analyze a richer set of strategies, a wider range of objectives, and greater levels of uncertainty than are typically considered by more sophisticated and computationally expensive models. We find that allowing for more combinations of risk mitigation strategies can help expand the solution set, help explain synergies and trade‐offs, and point to strategies that can improve outcomes.
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- 2021
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11. The Major Roles of Climate Warming and Ecological Competition in the Small-scale Coastal Fishery in French Guiana
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Abdoul Ahad Cisse, Luc Doyen, Fabian Blanchard, Nicolas Sanz, Coralie Kersulec, Helene Gomes, Groupe de Recherche en Economie Théorique et Appliquée (GREThA), Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Université de Bordeaux (UB), Centre National de la Recherche Scientifique (CNRS), and Université de Guyane (UG)
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0106 biological sciences ,Model Of Intermediate Complexity ,010504 meteorology & atmospheric sciences ,Marine Biodiversity ,Climate Change ,Fishing ,Biodiversity ,Fisheries ,Climate change ,Climate Models ,Oceanography ,01 natural sciences ,Ecosystems ,Fishing Effort ,Multi-species ,Intermediate Complexity ,Ecosystem Approach ,Ecosystem ,Marine ecosystem ,14. Life underwater ,Surface Waters ,Marine biodiversity ,Multi-fleet fishery ,ComputingMilieux_MISCELLANEOUS ,0105 earth and related environmental sciences ,General Environmental Science ,Mammals ,Biomass (ecology) ,[QFIN]Quantitative Finance [q-fin] ,010604 marine biology & hydrobiology ,Global warming ,Exclusion principle ,French Guiana ,Fishery ,Geography ,Fish ,13. Climate action ,Multi-Fleet Fishery ,[SDE]Environmental Sciences ,Climate Warming ,Exclusion Principle ,Climate model ,Models of Intermediate Complexity (MICE) ,Multi-Species - Abstract
Marine ecosystems, biodiversity, and fisheries are under strain worldwide due to global changes including climate warming and demographic pressure. To address this issue, many scientists and stakeholders advocate the use of an ecosystem approach for fisheries that integrates the numerous ecological and economic complexities at play rather than focusing on the management of individual target species. However, the operationalization of such an ecosystem approach remains challenging, especially from a bio-economic standpoint. Here, to address this issue, we propose a model of intermediate complexity (MICE) relying on multi-species, multi-fleet, and resource-based dynamics. Climate change effects are incorporated through an envelope model for the biological growth of fish species as a function of sea surface temperature. The model is calibrated for the small-scale fishery in French Guiana using a time series of fish landings and fishing effort from 2006 to 2018. From the calibrated model, a predictive fishing effort projection and RCP climate scenarios derived from IPCC, we explore the ecosystem dynamics and the fishery production at the horizon 2100. Our results demonstrate the long-term detrimental impact of both climate change and ecological competition on fish biodiversity. The prognosis is particularly catastrophic under the most pessimistic climate scenario, with a potential collapse of both biomass targeted species and fishing activity by 2100. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG.
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- 2021
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12. ADHERENCE TO THE HELPING BABIES BREATHE STRATEGY AT DELIVERY ROOM OF AN INSTITUTION LEVEL II OF CALI (COLOMBIA), YEAR 2017: CROSS SECTIONAL STUDY
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Paola Andrea Calvo-Bolaños, Sandra Patricia Moreno-Reyes, Víctor Hugo Estupiñán-Pérez, Angela M. Cubides-Munévar, and Freiser Eceomo Cruz-Mosquera
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medicine.medical_specialty ,Spontaneous vaginal delivery ,neonatal mortality ,asfixia ,lcsh:Gynecology and obstetrics ,reanimación cardiopulmonar básica ,03 medical and health sciences ,0302 clinical medicine ,newborn ,030225 pediatrics ,recién nacido ,Continuous education ,Medicine ,030212 general & internal medicine ,mortalidad neonatal ,Positive pressure ventilation ,lcsh:RG1-991 ,business.industry ,Obstetrics ,Delivery room ,Obstetrics and Gynecology ,Gestational age ,Congenital malformations ,asphyxia ,University hospital ,Intermediate complexity ,business ,basic cardiopulmonary resuscitation - Abstract
RESUMEN Objetivo: determinar la adherencia global y por componentes a la estrategia minuto de oro en médicos que atienden recién nacidos en una entidad de mediano nivel de complejidad. Materiales y métodos: estudio de corte transversal; se incluyeron recién nacidos vivos de partos vaginales espontáneos atendidos por médicos pediatras, ginecólogos o internos en sala de partos de un hospital universitario de la ciudad de Cali, Colombia, en el 2017. Se excluyeron fetos con mal- formaciones congénitas mayores, gemelares y con menos de 34 semanas de edad gestacional. Muestreo sistemático. Tamaño muestral: 150 recién nacidos. Se evaluaron las características basales de los recién nacidos y sus madres, y la adherencia a la estrategia minuto de oro y sus componentes. Se hizo análisis descriptivo. Resultados: la adherencia al minuto de oro en médicos pediatras fue del 65,6 % (IC 95 %: 53,8-78,4), en ginecobstetras, de 33,33 % (IC 95 %: 4,3-77,7), y en médicos internos, de 75,3 % (IC 95 %: 64,8- 85,1). La menor frecuencia se dio en la colocación del gorro al recién nacido, 64,90 % (IC 95 %: 56,7- 72,4), y poner al bebé piel a piel sobre la madre, 65 % (IC 95 %: 55,9-74,4); la mayor frecuencia se presentó en cubrir al recién nacido con paños calientes, 98,6 % (IC 95 %: 95,3-99,8), y la ventilación con presión positiva en los casos en los que no había respuesta a la estimulación inicial, 100 % (IC 95 %: 30-100). Conclusiones: los resultados obtenidos sobre el grado de adherencia de los profesionales sugieren la necesidad de realizar procesos continuos de educación y evaluación sobre la aplicación de esta estrategia de reconocida efectividad en las institu- ciones que ofrecen el servicio de atención de partos. ABSTRACT Objective: To determine adherence, overall and by components, to the Helping Babies Breathe strategy by physicians caring for neonates in an intermediate complexity institution. Materials and Methods: Cross-sectional study that included live neonates born by spontaneous vaginal delivery and who received care from pediatricians, gynecologists or interns in the delivery room of a university hospital in the city of Cali, Colombia, in 2017. Fetuses with major congenital malformations, twins, and neonates with less than 34 weeks of gestational age were excluded. Sampling was systematic and the sample size was of 150 neonates. Baseline neonatal and maternal characteristics were assessed, as well as adherence to the Helping Babies Breathe strategy and its components. A descriptive analysis was performed. Results: Adherence to the Helping Babies Breathe was 65.6% (95% CI 53.8-78.4) for pediatricians, 33.33% (95% CI: 4,3-77,7) for obstetricians and gynecologists, and 75.3% (95% CI: 64,8-85,1) for interns. The lowest frequency was found for cap placement on the neonate’s head, 64.90% (95% CI: 56.7-72.4), and placement of the baby in contact with the mother’s skin, 65% (95% CI: 55.9-74.4); the highest frequency was found for covering the baby with warm blankets, 98,6% (95% CI: 95.3-99.8), and positive pressure ventilation in those cases of absent response to initial stimulation, 100% (95% CI 30-100). Conclusions: Results pertaining to the degree of adherence on the part of the practitioners suggest the need to implement continuous education and evaluation processes focused on the application of this strategy which has been shown to be effective in institutions offering childbirth care.
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- 2019
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13. The Stability of the AMOC During Heinrich Events Is Not Dependent on the AMOC Strength in an Intermediate Complexity Earth System Model Ensemble
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Amy C. Clement, Lisa N. Murphy, and Marlos Goes
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Atmospheric Science ,Intermediate complexity ,Water mass ,010504 meteorology & atmospheric sciences ,Climatology ,Paleontology ,Earth system model ,010502 geochemistry & geophysics ,Oceanography ,01 natural sciences ,Stability (probability) ,Geology ,0105 earth and related environmental sciences - Published
- 2019
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14. Effectiveness of the National Quality Control Program in Mycology of Argentina and performance evaluation of participating laboratorios
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Ruben Abrantes, Guillermina Isla, Constanza Giselle Taverna, Nicolás Refojo, María Cristina Rivas, Mariana Mazza, Graciela Davel, Alejandra Hevia, Cristina Elena Canteros, Susana Córdoba, Mariana Viale, Nadia Soledad Bueno, Adriana Toranzo, and María C Lúpez Joffre
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Microbiology (medical) ,Quality Control ,medicine.medical_specialty ,media_common.quotation_subject ,Argentina ,Effectiveness ,Mycology ,Microbiology ,Quality of results ,Proficiency testing ,Low complexity ,03 medical and health sciences ,Quality control program ,High complexity ,medicine ,Humans ,Quality (business) ,Medical physics ,media_common ,0303 health sciences ,Micología ,Programa de controlde calidad ,Evaluación dedesempe˜no ,Efectividad ,030306 microbiology ,business.industry ,Diagnostic Tests, Routine ,User satisfaction ,Laboratory performance ,Quality control ,General Medicine ,Continuous training ,Intermediate complexity ,business ,Laboratories - Abstract
The National Quality Control Program in Mycology (PNCCM) of Argentina was establishedin 1996 to improve the quality of the mycological diagnosis, to help establish and to setup standardized procedures and continuous training of laboratory staff. The aim of this studywas to assess the effectiveness of the PNCCM in the 1996---2018 period. Data from the NationalMycology Laboratory Network (NMLN) and PNCCM database was used to estimate the increasein the number of controlled laboratories and jurisdictions, the percentage of participation, theimprovement in the quality of results and the adherence to the program. Satisfaction surveyswere performed to assess user satisfaction. The number of controlled laboratories increasedfrom 29 to 146; participation increased from 49% to 93% and general adherence was 72% inthe evaluated period (1996---2018). Improvement in the quality of the results was 15% for lowcomplexity samples; 7% for intermediate complexity samples and 14% for the identification ofhigh complexity strains. Up to 84% of the users consider the PNCCM to be ‘‘very good’’ and 16%‘‘satisfactory’’. These results show the importance of the PNCCM, which is widely accepted bymycological diagnostic laboratories from Argentina. Resumen En 1996 se creó el Programa Nacional de Control de Calidad en Micología (PNCCM)de Argentina con el objetivo de mejorar la calidad del diagnóstico micológico, colaborar enel establecimiento de procedimientos estandarizados en aquellos laboratorios que carecen deellos y contribuir a la capacitación continua del personal.El objetivo de este estudio fue evaluar la efectividad del PNCCM en el período 1996-2018.Se utilizaron los datos de la base de la Red Nacional de Laboratorios de Micología (RNLM) ydel PNCCM para estimar el aumento en el número de laboratorios controlados y el porcentajede participación, la mejora de la calidad de los resultados y la adhesión al programa. Paraevaluar el grado de satisfacción de los usuarios, se analizaron las encuestas de satisfacción delos participantes. En el período evaluado, el número de laboratorios controlados aumentó de 29a 146, la participación aumentó de 49% a 93% y la adherencia general de los participantes fue del72%. La mejora de la calidad de los resultados de los laboratorios fue del 15% para muestras debaja complejidad, 7% para muestras de complejidad intermedia y 14% para la identificación decepas de alta complejidad. El 84% de los usuarios considera que el PNCCM es muy bueno y el 16%que es satisfactorio. Estos resultados evidencian la importancia del PNCCM, que es ampliamenteaceptado por los laboratorios que realizan diagnóstico micológico en nuestro país.
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- 2021
15. Is there warming in the pipeline? A multi-model analysis of the Zero Emissions Commitment from CO2
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MacDougall, Andrew H., Frolicher, Thomas L., Jones, Chris D., Rogelj, Joeri, Matthews, H. Damon, Zickfeld, Kirsten, Arora, Vivek K., Barrett, Noah J., Brovkin, Victor, Burger, Friedrich A., Eby, Michel, Eliseev, Alexey, Hajima, Tomohiro, Holden, Philip B., Jeltsch-Thommes, Aurich, Koven, Charles, Mengis, Nadine, Menviel, Laurie, Michou, Martine, Mokhov, Igor I., Oka, Akira, Schwinger, Jorg, Seferian, Roland, Shaffer, Gary, Sokolov, Andrei, Tachiiri, Kaoru, Tjiputra, Jerry, Wiltshire, Andrew, Ziehn, Tilo, MacDougall, Andrew H., Frolicher, Thomas L., Jones, Chris D., Rogelj, Joeri, Matthews, H. Damon, Zickfeld, Kirsten, Arora, Vivek K., Barrett, Noah J., Brovkin, Victor, Burger, Friedrich A., Eby, Michel, Eliseev, Alexey, Hajima, Tomohiro, Holden, Philip B., Jeltsch-Thommes, Aurich, Koven, Charles, Mengis, Nadine, Menviel, Laurie, Michou, Martine, Mokhov, Igor I., Oka, Akira, Schwinger, Jorg, Seferian, Roland, Shaffer, Gary, Sokolov, Andrei, Tachiiri, Kaoru, Tjiputra, Jerry, Wiltshire, Andrew, and Ziehn, Tilo
- Abstract
The Zero Emissions Commitment (ZEC) is the change in global mean temperature expected to occur following the cessation of net CO2 emissions and as such is a critical parameter for calculating the remaining carbon budget. The Zero Emissions Commitment Model Intercomparison Project (ZECMIP) was established to gain a better understanding of the potential magnitude and sign of ZEC, in addition to the processes that underlie this metric. A total of 18 Earth system models of both full and intermediate complexity participated in ZECMIP. All models conducted an experiment where atmospheric CO2 concentration increases exponentially until 1000 PgC has been emitted. Thereafter emissions are set to zero and models are configured to allow free evolution of atmospheric CO2 concentration. Many models conducted additional second-priority simulations with different cumulative emission totals and an alternative idealized emissions pathway with a gradual transition to zero emissions. The inter-model range of ZEC 50 years after emissions cease for the 1000 PgC experiment is 0:36 to 0.29 degrees C, with a model ensemble mean of 0:07 degrees C, median of 0:05 degrees C, and standard deviation of 0.19 degrees C. Models exhibit a wide variety of behaviours after emissions cease, with some models continuing to warm for decades to millennia and others cooling substantially. Analysis shows that both the carbon uptake by the ocean and the terrestrial biosphere are important for counteracting the warming effect from the reduction in ocean heat uptake in the decades after emissions cease. This warming effect is difficult to constrain due to high uncertainty in the efficacy of ocean heat uptake. Overall, the most likely value of ZEC on multi-decadal timescales is close to zero, consistent with previous model experiments and simple theory.
- Published
- 2020
16. Challenges of applying multicellular tumor spheroids in preclinical phase
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Sangwoo Kwon, Kyung Sook Kim, and Se Jik Han
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Multicellular tumor spheroids ,Cancer Research ,Growth kinetics ,Microfluidics ,Tumor spheroid ,High-throughput ,Review ,Computational biology ,Biology ,lcsh:RC254-282 ,03 medical and health sciences ,0302 clinical medicine ,In vivo ,Biological property ,Genetics ,lcsh:QH573-671 ,030304 developmental biology ,0303 health sciences ,lcsh:Cytology ,Spheroid ,lcsh:Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,Therapeutic efficacy ,Intermediate complexity ,Multicellular organism ,Drug screening ,Oncology ,Preclinical phase ,030220 oncology & carcinogenesis - Abstract
The three-dimensional (3D) multicellular tumor spheroids (MCTs) model is becoming an essential tool in cancer research as it expresses an intermediate complexity between 2D monolayer models and in vivo solid tumors. MCTs closely resemble in vivo solid tumors in many aspects, such as the heterogeneous architecture, internal gradients of signaling factors, nutrients, and oxygenation. MCTs have growth kinetics similar to those of in vivo tumors, and the cells in spheroid mimic the physical interaction of the tumors, such as cell-to-cell and cell-to-extracellular matrix interactions. These similarities provide great potential for studying the biological properties of tumors and a promising platform for drug screening and therapeutic efficacy evaluation. However, MCTs are not well adopted as preclinical tools for studying tumor behavior and therapeutic efficacy up to now. In this review, we addressed the challenges with MCTs application and discussed various efforts to overcome the challenges.
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- 2021
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17. Characterisation of Atlantic meridional overturning hysteresis using Langevin dynamics
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Jelle van den Berk, Wilco Hazeleger, and Sybren Drijfhout
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010504 meteorology & atmospheric sciences ,lcsh:Dynamic and structural geology ,Forcing (mathematics) ,01 natural sciences ,Langevin model ,Physics::Geophysics ,03 medical and health sciences ,lcsh:QE500-639.5 ,Langevin dynamics ,lcsh:Science ,Physics::Atmospheric and Oceanic Physics ,030304 developmental biology ,0105 earth and related environmental sciences ,0303 health sciences ,Meridional overturning ,lcsh:QE1-996.5 ,Mechanics ,Langevin equation ,lcsh:Geology ,Intermediate complexity ,Hysteresis ,13. Climate action ,General Earth and Planetary Sciences ,Climate model ,lcsh:Q ,Geology - Abstract
Hysteresis diagrams of the Atlantic meridional overturning circulation (AMOC) under freshwater forcing from climate models of intermediate complexity are fitted to a simple model based on the Langevin equation. A total of six parameters are sufficient to quantitatively describe the collapses seen in these simulations. Reversing the freshwater forcing results in asymmetric behaviour that is less well captured and appears to require a more complicated model. The Langevin model allows for comparison between models that display an AMOC collapse. Differences between the climate models studied here are mainly due to the strength of the stable AMOC and the strength of the response to a freshwater forcing.
- Published
- 2021
18. Timescale‐dependent <scp>AMOC–AMO</scp> relationship in an earth system model of intermediate complexity
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Daehyun Kim, Hyo Jeong Kim, and Soon Il An
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Atmospheric Science ,Intermediate complexity ,Climatology ,Environmental science ,Earth system model - Published
- 2020
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19. Dynamical Landscape and Multistability of a Climate Model
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Tobias Grafke, Alessandro Laio, Georgios Margazoglou, and Valerio Lucarini
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FOS: Computer and information sciences ,010504 meteorology & atmospheric sciences ,Computer science ,STOCHASTIC RESONANCE ,General Physics and Astronomy ,01 natural sciences ,09 Engineering ,010305 fluids & plasmas ,ENERGY ,Statistics - Machine Learning ,manifold learning ,multistability ,HEAT-TRANSPORT ,State space ,Statistical physics ,Water cycle ,Independent data ,QC ,Physics::Atmospheric and Oceanic Physics ,02 Physical Sciences ,EARTH SYSTEM MODEL ,Entropy production ,ENTROPY PRODUCTION ,General Engineering ,Energy landscape ,Computational Physics (physics.comp-ph) ,stat.ML ,Multidisciplinary Sciences ,Physics - Atmospheric and Oceanic Physics ,INDUCED ESCAPE ,Climatology ,Science & Technology - Other Topics ,non-equilibrium systems ,Physics - Computational Physics ,Geology ,General Mathematics ,CIRCULATION ,FOS: Physical sciences ,INTERMEDIATE COMPLEXITY ,physics.ao-ph ,Machine Learning (stat.ML) ,Structural basin ,Settore FIS/03 - Fisica della Materia ,Physics::Geophysics ,data-driven methods ,0103 physical sciences ,cond-mat.stat-mech ,010306 general physics ,01 Mathematical Sciences ,Multistability ,Condensed Matter - Statistical Mechanics ,0105 earth and related environmental sciences ,Science & Technology ,Statistical Mechanics (cond-mat.stat-mech) ,ICE ,Nonlinear dimensionality reduction ,15. Life on land ,ATMOSPHERE ,climate modelling ,Intermediate complexity ,physics.comp-ph ,13. Climate action ,Atmospheric and Oceanic Physics (physics.ao-ph) ,quasi-potential theory ,Climate model - Abstract
We apply two independent data analysis methodologies to locate stable climate states in an intermediate complexity climate model and analyze their interplay. First, drawing from the theory of quasipotentials, and viewing the state space as an energy landscape with valleys and mountain ridges, we infer the relative likelihood of the identified multistable climate states, and investigate the most likely transition trajectories as well as the expected transition times between them. Second, harnessing techniques from data science, specifically manifold learning, we characterize the data landscape of the simulation output to find climate states and basin boundaries within a fully agnostic and unsupervised framework. Both approaches show remarkable agreement, and reveal, apart from the well known warm and snowball earth states, a third intermediate stable state in one of the two climate models we consider. The combination of our approaches allows to identify how the negative feedback of ocean heat transport and entropy production via the hydrological cycle drastically change the topography of the dynamical landscape of Earth's climate., 28 pages, 12 figures plus Supplementary Material. Revised version
- Published
- 2020
20. Collapse of the Atlantic Meridional Overturning described by Langevin dynamics
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Jelle van den Berk, Wilco Hazeleger, and Sybren Drijfhout
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Langevin equation ,Intermediate complexity ,Meridional overturning ,Collapse (topology) ,Climate model ,Forcing (mathematics) ,Mechanics ,Langevin dynamics ,Geology ,Physics::Atmospheric and Oceanic Physics ,Physics::Geophysics - Abstract
Using a machine learning technique, collapse trajectories of the Atlantic Meridional Overturning Circulation from climate models of intermediate complexity are fitted to a simple model based on the Langevin equation. A total of six parameters are sufficient to quantitatively describe the collapses seen in these simulations under a freshwater forcing. Reversing the freshwater forcing results in asymmetric behaviour that is less well captured and would require a more complicated model.
- Published
- 2020
21. A network scale, intermediate complexity model for simulating channel evolution over years to decades
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Brian P. Bledsoe and Roderick W. Lammers
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Hydrology ,Watershed ,010504 meteorology & atmospheric sciences ,0208 environmental biotechnology ,02 engineering and technology ,01 natural sciences ,River bed ,020801 environmental engineering ,Watershed scale ,Intermediate complexity ,Aggradation ,Erosion ,Sediment transport ,Geology ,Bank erosion ,0105 earth and related environmental sciences ,Water Science and Technology - Abstract
Excessive river erosion and sedimentation threatens critical infrastructure, degrades aquatic habitat, and impairs water quality. Tools for predicting the magnitude of erosion, sedimentation, and channel evolution processes are needed for effective mitigation and management. We present a new numerical model that simulates coupled river bed and bank erosion at the watershed scale. The model uses modified versions of Bagnold’s sediment transport equation to simulate bed erosion and aggradation, as well as a simplified Bank Stability and Toe Erosion Model (BSTEM) to simulate bank erosion processes. The model is mechanistic and intermediate complexity, accounting for the dominant channel evolution processes while limiting data requirements. We apply the model to a generic test case of channel network response following a disturbance and the results match physical understanding of channel evolution. The model was also tested on two field data sets: below Parker Dam on the lower Colorado River and the North Fork Toutle River (NFTR) which responded dramatically to the 1980 eruption of Mount St. Helens. It accurately predicts observed channel incision and bed material coarsening on the Colorado River, as well as observations for the upstream 18 km of the NFTR watershed. The model does not include algorithms for extensive lateral migration and avulsions and therefore did not perform well in the lower NFTR where the channel migrated across a wide valley bottom. REM is parsimonious and useful for simulating network scale channel change in single thread systems responding to disturbance.
- Published
- 2018
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22. Description and Evaluation of the MIT Earth System Model (MESM)
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Chris E. Forest, Ronald G. Prinn, David W. Kicklighter, Chien Wang, Andrei P. Sokolov, Erwan Monier, Sebastian D. Eastham, Alex G. Libardoni, Xiang Gao, Benjamin Brown-Steiner, C. Adam Schlosser, Joint Program in Oceanography, Massachusetts Institute of Technology. Center for Global Change Science, Massachusetts Institute of Technology. Department of Aeronautics and Astronautics, Sokolov, Andrei P, Schlosser, Courtney Adam, Wang, Chien, Monier, Erwan, Brown-Steiner, Benjamin E, Prinn, Ronald G, Gao, Xiang, and Eastham, Sebastian David
- Subjects
Global and Planetary Change ,Global system ,010504 meteorology & atmospheric sciences ,Meteorology ,Climate risk ,Atmospheric model ,010502 geochemistry & geophysics ,Policy analysis ,01 natural sciences ,System model ,Intermediate complexity ,General Earth and Planetary Sciences ,Environmental Chemistry ,Environmental science ,Earth system model ,0105 earth and related environmental sciences - Abstract
The Massachusetts Institute of Technology Integrated Global System Model (IGSM) is designed for analyzing the global environmental changes that may result from anthropogenic causes, quantifying the uncertainties associated with the projected changes, and assessing the costs and environmental effectiveness of proposed policies to mitigate climate risk. The IGSM consists of the Massachusetts Institute of Technology Earth System Model (MESM) of intermediate complexity and the Economic Projections and Policy Analysis model. This paper documents the current version of the MESM, which includes a two-dimensional (zonally averaged) atmospheric model with interactive chemistry coupled to the zonally averaged version of Global Land System model and an anomaly-diffusing ocean model., United States. Department of Energy. Office of Science (DE-FG02-94ER61937)
- Published
- 2018
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23. An intermediate‐complexity model for four‐dimensional variational data assimilation including moist processes
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Nedjeljka Žagar, Žiga Zaplotnik, and Nils Gustafsson
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Atmospheric Science ,Intermediate complexity ,Data assimilation ,010504 meteorology & atmospheric sciences ,010502 geochemistry & geophysics ,Atmospheric sciences ,01 natural sciences ,0105 earth and related environmental sciences ,Mathematics - Abstract
An intermediate-complexity model for four-dimensional variational data assimilation including moist processes
- Published
- 2018
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24. A Pilot Climate Sensitivity Study Using the CEN Coupled Adjoint Model (CESAM)
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Detlef Stammer, Andrey Vlasenko, Silke Schubert, Armin Köhl, Frank Lunkeit, and Ion Matei
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Atmospheric Science ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Scale (ratio) ,010502 geochemistry & geophysics ,01 natural sciences ,The arctic ,Intermediate complexity ,Data assimilation ,Climatology ,Sea ice ,Climate sensitivity ,Environmental science ,Climate model ,Sea surface salinity ,0105 earth and related environmental sciences - Abstract
A pilot coupled climate sensitivity study is presented based on the newly developed adjoint coupled climate model, Centrum für Erdsystemforschung und Nachhaltigkeit (CEN) Earth System Assimilation Model (CESAM). To this end the components of the coupled forward model are summarized, and the generation of the adjoint code out of the model forward code through the application of the Transformation of Algorithms in FORTRAN (TAF) adjoint compiler is discussed. It is shown that simulations of the intermediate-complexity CESAM are comparable in quality to CMIP-type coupled climate models, justifying the usage of the model to compute adjoint sensitivities of the northern Europe near-surface temperature to anomalies in surface temperature, sea surface salinity, and sea ice over the North Atlantic and the Arctic on time scales of up to one month. Results confirm that on a time scale of up to a few days surface temperatures over northern Europe are influenced by Atlantic temperature anomalies just upstream of the target location. With increasingly longer time lapse, however, it is the influence of SSTs over the central and western North Atlantic on the overlying atmosphere and the associated changes in storm-track pattern that dominate the evolution of the surface European temperature. Influences of surface salinity and sea ice on the northern European temperature appear to have similar sensitivity mechanisms, invoked indirectly through their influence on near-surface temperature anomalies. The adjoint study thus confirms that the SST’s impact on the atmospheric dynamics, notably storm tracks, is the primary cause for the influence of northern European temperature changes.
- Published
- 2018
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25. Constructing partial words with subword complexities not achievable by full words
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Blanchet-Sadri, F., Chakarov, Aleksandar, Manuelli, Lucas, Schwartz, Jarett, and Stich, Slater
- Subjects
- *
COMPUTATIONAL complexity , *MATHEMATICAL sequences , *ALPHABET -- Data processing , *MATHEMATICAL notation , *MATCHING theory , *INTEGERS , *MATHEMATICAL models - Abstract
Abstract: Partial words are sequences over a finite alphabet that may contain wildcard symbols, called holes, which match, or are compatible with, all letters in the alphabet ((full) words are just partial words without holes). The subword complexity function of a partial word over a finite alphabet assigns to each positive integer, , the number, , of distinct full words over that are compatible with factors of length of . In this paper, with the help of our so-called hole functions, we construct infinite partial words such that for any real number . In addition, these partial words have the property that there exist infinitely many non-negative integers satisfying . Combining these results with earlier ones on full words, we show that this represents a class of subword complexity functions not achievable by full words. We also construct infinite partial words with intermediate subword complexity, that is, between polynomial and exponential. [Copyright &y& Elsevier]
- Published
- 2012
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26. On intermediate factorial languages
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Shur, Arseny M.
- Subjects
- *
FACTOR analysis , *POLYNOMIALS , *EXPONENTIAL functions , *MATHEMATICAL analysis , *MACHINE theory , *COMPUTATIONAL complexity , *ALPHABETS - Abstract
Abstract: We prove that factorial languages defined over non-trivial finite alphabets under some natural conditions have intermediate complexity functions, i.e., the number of words in such a language grows faster than any polynomial but slower than any exponential function. [Copyright &y& Elsevier]
- Published
- 2009
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27. Journal of Dairy Science
- Author
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Michael J. VandeHaar, Robin R. White, Mark D. Hanigan, R. Garnett, H. Tran, Y. Roman-Garcia, Tyler McGill, Paul J. Kononoff, Jeffrey L. Firkins, and Dairy Science
- Subjects
0301 basic medicine ,model evaluation ,Rumen ,Mean squared prediction error ,National Academy of Sciences, U.S ,Root mean square ,03 medical and health sciences ,C protein ,Animal science ,Genetics ,Animals ,National Research Council (2001) dairy model ,duodenal flow ,Independent data ,Mathematics ,business.industry ,0402 animal and dairy science ,04 agricultural and veterinary sciences ,Models, Theoretical ,Animal Feed ,040201 dairy & animal science ,United States ,Diet ,Biotechnology ,Intermediate complexity ,030104 developmental biology ,Concordance correlation coefficient ,Research council ,Animal Science and Zoology ,Dietary Proteins ,business ,Food Science - Abstract
This work evaluated the National Research Council (NRC) dairy model (2001) predictions of rumen undegradable (RUP) and degradable (RDP) protein compared with measured postruminal non-ammonia, nonmicrobial (NANMN) and microbial N flows. Models were evaluated using the root mean squared prediction error (RMSPE) as a percent of the observed mean; mean and slope biases as percentages of mean squared prediction error (MSPE), and concordance correlation coefficient, (CCC). The NRC (2001) over-estimated NANMN by 18% and under-estimated microbial N by 14%. Both responses had large mean biases (19% and 20% of MSPE, respectively); and NANMN had a slope Dias (22% of MSPE). The NRC NANMN estimate had high RMSPE (46% of observed mean) and low CCC (0.37); updating feed library A, B, and C protein fractions and degradation rate (K-d) estimates with newer literature only marginally improved fit. The re-fit NRC models for NANMN and microbial N had CCC of 0.89 and 0.94, respectively. When compared with a prediction of NANMN as a static mean fraction of N intake; the re-derived NRC approach did not have improved fit. A protein system of intermediate complexity was derived in an attempt to estimate NANMN with improved fit compared with the static mean NANMN model. In this system, postruminal appearance of A, B, and C protein fractions were predicted in a feed-type specific mariner rather than from estimated passage and degradation rates. In a comparison to independent data. achieved through cross-validation; the new protein system improved RMSPE (34 vs. 36% of observed mean) and CCC (0.42 vs. 0.30) compared with the static mean NANMN model. When the NRC microbial N equation was re-derived, the RDP term dropped from the model. Consequently, 2 new microbial protein equations were formulated, both used a saturating (increasing at a decreasing rate) form: one saturated with respect to TDN and the other saturated over increasing intakes of rumen degraded starch and NDF. Both equations expressed maximal microbial N production as a linear function of RDP intake. The function relating microbial N to intake of rumen degradable carbohydrate improved RMSPE (24 vs. 28% of the observed mean) and CCC (0.63 vs 0.30) compared with the re-derived NRC model. The newly derived equations showed modest improvements in model fit and improved capacity to account for known biological effects; however, substantial variability in NANMN and microbial N estimates remained unexplained. Agricultural and Food Research Initiative Competitive Grant [2011-68004-30340]; USDA National Institute of Food and Agriculture (Washington, DC) [2015-03656]; Papillon (Easton, MD) In addition to the funding sources listed in the title page footnote, funding for this project was provided by Agricultural and Food Research Initiative Competitive Grant no. 2011-68004-30340 and no. 2015-03656 from the USDA National Institute of Food and Agriculture (Washington, DC) and by Papillon (Easton, MD). The authors acknowledge the contributions of the late L. F. Reutzel (Laud O'Lakes/Purina Mills) to portions of the initial code used in the project and the late Gale Bateman (Akey, Lewisburg, OH) for help in assembling and collating the dietary ingredient data.
- Published
- 2017
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28. New insights into cycling of 231Pa and 230Th in the Atlantic Ocean
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Jörg Lippold, Thomas F. Stocker, Johannes Rempfer, Samuel L Jaccard, and Fortunat Joos
- Subjects
geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Advection ,530 Physics ,North Atlantic Deep Water ,010502 geochemistry & geophysics ,01 natural sciences ,Sink (geography) ,Intermediate complexity ,Geophysics ,Oceanography ,13. Climate action ,Space and Planetary Science ,Geochemistry and Petrology ,Steady state distribution ,Earth and Planetary Sciences (miscellaneous) ,14. Life underwater ,Cycling ,Scavenging ,Seabed ,Geology ,550 Earth sciences & geology ,0105 earth and related environmental sciences - Abstract
We use the Bern3D model of intermediate complexity to examine the marine cycle of isotopes 231Pa and 230Th and the relationship between the particle-bound ratio Pa p / Th p and changes in the formation of the North Atlantic Deep Water (NADW). Model parameters describing reversible scavenging of isotopes by organic particles, opal, calcite and resuspended sediments were systematically varied and alternative sink parametrisations explored. It proves difficult to simultaneously achieve a good agreement with observations of dissolved and particle-associated concentrations of 231Pa and 230Th ( Pa d , Th d , Pa p , Th p ) as well as the particle-bound ratio Pa p / Th p within the classical concept of reversible scavenging alone. Agreement between simulated and observed Pa d , Th d and estimates of mean ocean residence times is improved by taking into account simplified representations of additional sinks at the sea floor (bottom scavenging) and at continental boundaries (boundary scavenging). We also find improved agreement between model and data by increasing lateral advection, in particular for Pa d . These results point to the importance of sink processes that act in addition to reversible scavenging to shape the steady state distribution of 231Pa and, to a lesser degree, of 230Th. In transient experiments in which the strength of the Atlantic meridional overturning circulation (AMOC) is periodically turned on and off, we find a strong statistical relationship between variations in AMOC strength and Pa p / Th p at great depths in the Northwest Atlantic region. These conclusions are robust across the range of sink parametrisations, that are consistent with estimates in the mean ocean residence time of 231Pa and 230Th. Our results indicate that the relationship between Pa p / Th p and AMOC-strength may not be fundamentally affected by uncertainties in sink processes, at least on the large spatial and temporal scale considered here, and support the idea that changes in Pa p / Th p in sediments of the Northwest Atlantic are indicative of changes in AMOC strength. Taking into account our simplified approach, our results indicate that the relationship between Pa p / Th p and AMOC-strength in the deep Northwest Atlantic is not affected by boundary scavenging or bottom scavenging. Our results thus support the idea that changes in Pa p / Th p in sediments of the Northwest Atlantic are indicative of changes in AMOC strength.
- Published
- 2017
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29. Myocardial slices come to age: an intermediate complexity in vitro cardiac model for translational research
- Author
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Samuel A. Watson, Filippo Perbellini, Cesare M. Terracciano, Fotios G. Pitoulis, and British Heart Foundation
- Subjects
Physiology ,Computer science ,Culture ,Reviews ,Translational research ,Cell Communication ,In Vitro Techniques ,Mechanical load ,Translational Research, Biomedical ,Physiology (medical) ,Animals ,Humans ,Myocardial slices ,1102 Cardiorespiratory Medicine and Haematology ,Potential impact ,Myocardium ,Microtomy ,Clinical Practice ,Intermediate complexity ,Editor's Choice ,Phenotype ,Cardiovascular System & Hematology ,In vitro heart models ,Cardiology and Cardiovascular Medicine ,Neuroscience ,Signal Transduction - Abstract
Although past decades have witnessed significant reductions in mortality of heart failure together with advances in our understanding of its cellular, molecular, and whole-heart features, a lot of basic cardiac research still fails to translate into clinical practice. In this review we examine myocardial slices, a novel model in the translational arena. Myocardial slices are living ultra-thin sections of heart tissue. Slices maintain the myocardium’s native function (contractility, electrophysiology) and structure (multicellularity, extracellular matrix) and can be prepared from animal and human tissue. The discussion begins with the history and current advances in the model, the different interlaboratory methods of preparation and their potential impact on results. We then contextualize slices’ advantages and limitations by comparing it with other cardiac models. Recently, sophisticated methods have enabled slices to be cultured chronically in vitro while preserving the functional and structural phenotype. This is more timely now than ever where chronic physiologically relevant in vitro platforms for assessment of therapeutic strategies are urgently needed. We interrogate the technological developments that have permitted this, their limitations, and future directions. Finally, we look into the general obstacles faced by the translational field, and how implementation of research systems utilizing slices could help in resolving these., Graphical Abstract Graphical Abstract
- Published
- 2019
30. Myocardial Slices: an Intermediate Complexity Platform for Translational Cardiovascular Research
- Author
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Filippo Perbellini, Cesare M. Terracciano, and Samuel A. Watson
- Subjects
0301 basic medicine ,Cardiac & Cardiovascular Systems ,Cell Communication ,030204 cardiovascular system & hematology ,CARDIOMYOCYTES ,Ventricular myocardium ,TISSUE-SLICES ,CULTURE ,Translational Research, Biomedical ,0302 clinical medicine ,RECORDINGS ,Medicine ,Pharmacology (medical) ,Myocytes, Cardiac ,Pharmacology & Pharmacy ,Tissue clearing ,Cardiac model ,General Medicine ,Cardiovascular physiology ,Vibratome ,SURVIVAL ,Multicellularity ,Original Article ,1115 Pharmacology and Pharmaceutical Sciences ,Cardiology and Cardiovascular Medicine ,Life Sciences & Biomedicine ,Organotypic heart slices ,Myocardial slice ,Cell Survival ,Cardiovascular research ,In Vitro Techniques ,03 medical and health sciences ,Slice preparation ,Animals ,Humans ,Pharmacology ,Tissue Survival ,Science & Technology ,business.industry ,TRANSPLANTATION ,Myocardium ,IN-VITRO ,Microtomy ,Transplantation ,MODEL ,Intermediate complexity ,030104 developmental biology ,Cardiovascular System & Hematology ,Cardiovascular System & Cardiology ,HEART SLICES ,business ,Biomedical engineering - Abstract
Myocardial slices, also known as “cardiac tissue slices” or “organotypic heart slices,” are ultrathin (100–400 μm) slices of living adult ventricular myocardium prepared using a high-precision vibratome. They are a model of intermediate complexity as they retain the native multicellularity, architecture, and physiology of the heart, while their thinness ensures adequate oxygen and metabolic substrate diffusion in vitro. Myocardial slices can be produced from a variety of animal models and human biopsies, thus providing a representative human in vitro platform for translational cardiovascular research. In this review, we compare myocardial slices to other in vitro models and highlight some of the unique advantages provided by this platform. Additionally, we discuss the work performed in our laboratory to optimize myocardial slice preparation methodology, which resulted in highly viable myocardial slices from both large and small mammalian hearts with only 2–3% cardiomyocyte damage and preserved structure and function. Applications of myocardial slices span both basic and translational cardiovascular science. Our laboratory has utilized myocardial slices for the investigation of cardiac multicellularity, visualizing 3D collagen distribution and micro/macrovascular networks using tissue clearing protocols and investigating the effects of novel conductive biomaterials on cardiac physiology. Myocardial slices have been widely used for pharmacological testing. Finally, the current challenges and future directions for the technology are discussed.
- Published
- 2019
31. Radiance Uncertainty Characterisation to Facilitate Climate Data Record Creation
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Emma R. Woolliams, Christopher J. Merchant, Gerrit Holl, and Jonathan P. D. Mittaz
- Subjects
Earth observation ,radiance ,010504 meteorology & atmospheric sciences ,Computer science ,Science ,0211 other engineering and technologies ,climate data record ,02 engineering and technology ,fundamental climate data record ,computer.software_genre ,01 natural sciences ,Set (abstract data type) ,remote sensing ,essential climate variable ,metrology ,uncertainty ,error budget ,error propagation ,Physics::Atmospheric and Oceanic Physics ,021101 geological & geomatics engineering ,0105 earth and related environmental sciences ,Propagation of uncertainty ,Computer Science::Computers and Society ,Metrology ,Intermediate complexity ,13. Climate action ,Radiance ,General Earth and Planetary Sciences ,Data mining ,computer - Abstract
The uncertainty in a climate data records (CDRs) derived from Earth observations in part derives from the propagated uncertainty in the radiance record (the fundamental climate data record, FCDR) from which the geophysical estimates in the CDR are derived. A common barrier to providing uncertainty-quantified CDRs is the inaccessibility to CDR creators of appropriate radiance uncertainty information in the FCDR. Here, we propose radiance uncertainty information designed directly to facilitate estimation of propagated uncertainty in derived CDRs at full resolution and in gridded products. Errors in Earth observations are typically highly structured and complex, and the uncertainty information we propose is of intermediate complexity, sufficient to capture the main variability in propagated uncertainty in a CDR, while avoiding unfeasible complexity or data volume. The uncertainty and error correlation characteristics of uncertainty are quantified for three classes of error with different propagation properties: independent, structured and common radiance errors. The meaning, mathematical derivations, practical evaluation and example applications of this set of uncertainty information are presented.
- Published
- 2019
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32. The Tragedy of Open Ecosystems
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Abdoul Ahad Cisse, Fabian Blanchard, Luc Doyen, Jean-Christophe Pereau, Nicolas Sanz, Groupe de Recherche en Economie Théorique et Appliquée (GREThA), Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)
- Subjects
0106 biological sciences ,Statistics and Probability ,Economics and Econometrics ,Biodiversity ,Bellman Optimization ,01 natural sciences ,Fish War ,Intermediate Complexity ,0502 economics and business ,Economics ,Ecosystem ,050207 economics ,[QFIN]Quantitative Finance [q-fin] ,business.industry ,010604 marine biology & hydrobiology ,Applied Mathematics ,Scale (chemistry) ,05 social sciences ,Environmental resource management ,Environmental economics ,Computer Graphics and Computer-Aided Design ,Computer Science Applications ,Computational Mathematics ,Intermediate complexity ,Markov perfect nash equilibrium ,Computational Theory and Mathematics ,Tragedy (event) ,Markov-Perfect Nash Equilibrium ,business - Abstract
This paper investigates the role played by cooperation for the sustainable harvesting of an ecosystem. To achieve this, a bio-economic model based on a multi-species dynamics with interspecific relationships and multi-agent catches is considered. A comparison between the non-cooperative and cooperative optimal strategies is carried out. Revisiting the Tragedy of Open Access and over-exploitation issues, it is first proved analytically how harvesting pressure is larger in the non-cooperative case for every species. Then it is examined to what extent gains from cooperation can also be derived for the state of the ecosystem. It turns out that cooperation clearly promotes the conservation of every species when the number of agents is high. When the number of agents remains limited, results are more complicated, especially if a species-by-species viewpoint is adopted. However, we identify two metrics involving the state of every species and accounting for their ecological interactions which exhibit gains from cooperation at the ecosystem scale in the general case. Numerical examples illustrate the mathematical findings.
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- 2016
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33. The Intermediate Complexity Atmospheric Research Model (ICAR)
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Jeffrey R. Arnold, Ethan Gutmann, Martyn P. Clark, Roy Rasmussen, and Idar Barstad
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Atmospheric Science ,Atmosphere (unit) ,010504 meteorology & atmospheric sciences ,Meteorology ,Advection ,0208 environmental biotechnology ,Climate change ,02 engineering and technology ,01 natural sciences ,Atmospheric research ,020801 environmental engineering ,Intermediate complexity ,Environmental science ,Precipitation ,Focus (optics) ,0105 earth and related environmental sciences ,Downscaling - Abstract
With limited computational resources, there is a need for computationally frugal models. This is particularly the case for atmospheric sciences, which have long relied on either simplistic analytical solutions or computationally expensive numerical models. The simpler solutions are inadequate for many problems, while the cost of numerical models makes their use impossible for many problems, most notably high-resolution climate downscaling applications spanning large areas, long time periods, and many global climate projections. Here the Intermediate Complexity Atmospheric Research model (ICAR) is presented to provide a new step along the modeling complexity continuum. ICAR leverages an analytical solution for high-resolution perturbations to wind velocities, in conjunction with numerical physics schemes, that is, advection and cloud microphysics, to simulate the atmosphere. The focus of the initial development of ICAR is for predictions of precipitation, and eventually temperature, humidity, and radiation at the land surface. Comparisons between ICAR and the Weather Research and Forecasting (WRF) Model for simulations over an idealized mountain are presented, as well as among ICAR, WRF, and the Parameter-Elevation Regressions on Independent Slopes Model (PRISM) observation-based product for a year-long simulation over the Colorado Rockies. In the ideal simulations, ICAR matches WRF precipitation predictions across a range of environmental conditions with a coefficient of determination r2 of 0.92. In the Colorado Rockies, ICAR, WRF, and PRISM show very good agreement, with differences between ICAR and WRF comparable to the differences between WRF and PRISM in the cool season. For these simulations, WRF required 140–800 times more computational resources than ICAR.
- Published
- 2016
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34. Assimilating atmospheric observations into the ocean using strongly coupled ensemble data assimilation
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Takemasa Miyoshi, Stephen G. Penny, Travis C. Sluka, and Eugenia Kalnay
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Strongly coupled ,Physics ,010504 meteorology & atmospheric sciences ,Meteorology ,Kalman filter ,Covariance ,010502 geochemistry & geophysics ,01 natural sciences ,Atmosphere ,Intermediate complexity ,Geophysics ,Data assimilation ,General Earth and Planetary Sciences ,Ensemble Kalman filter ,Statistical physics ,Physics::Atmospheric and Oceanic Physics ,0105 earth and related environmental sciences - Abstract
The local ensemble transform Kalman filter (LETKF) is used to develop a strongly coupled data assimilation (DA) system for an intermediate complexity ocean-atmosphere coupled model. Strongly coupled DA uses the cross-domain error covariance from a coupled-model background ensemble to allow observations in one domain to directly impact the state of the other domain during the analysis update. This method is compared to weakly coupled DA in which the coupled model is used for the background, but the cross-domain error covariance is not utilized. We perform an observing system simulation experiment with atmospheric observations only. Strongly coupled DA reduces the ocean analysis errors compared to weakly coupled DA, and the higher accuracy of the ocean also improves the atmosphere. The LETKF system design presented should allow for easy implementation of strongly coupled DA with other types of coupled models.
- Published
- 2016
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35. Corrigendum to 'A process-based fire parameterization of intermediate complexity in a Dynamic Global Vegetation Model' published in Biogeosciences, 9, 2761–2780, 2012
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Xiaodong Zeng, Feng-Min Li, and Samuel Levis
- Subjects
lcsh:QE1-996.5 ,lcsh:Life ,Dynamic global vegetation model ,lcsh:Geology ,lcsh:QH501-531 ,Intermediate complexity ,lcsh:QH540-549.5 ,Scientific method ,Climatology ,Environmental science ,lcsh:Ecology ,Biogeosciences ,Ecology, Evolution, Behavior and Systematics ,Earth-Surface Processes - Published
- 2018
36. IMOGEN: an intermediate complexity model to evaluate terrestrial impacts of a changing climate
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Lina M. Mercado, Peter Good, Rosie A. Fisher, Martin Best, Chris Huntingford, Ben B. B. Booth, Spencer Liddicoat, Graham P. Weedon, Mark R. Lomas, C. D. Jones, Nicola Gedney, Allan Spessa, A. C. Everitt, Jason Lowe, Stephen Sitch, and Przemyslaw Zelazowski
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lcsh:Geology ,Biogeochemical cycle ,Intermediate complexity ,Greenhouse gas ,Climatology ,lcsh:QE1-996.5 ,Extrapolation ,Climate change ,Environmental science ,Climate model ,Vegetation ,Transient climate simulation ,Atmospheric sciences - Abstract
We present a computationally efficient modelling system, IMOGEN, designed to undertake global and regional assessment of climate change impacts on the physical and biogeochemical behaviour of the land surface. A pattern-scaling approach to climate change drives a gridded land surface and vegetation model MOSES/TRIFFID. The structure allows extrapolation of General Circulation Model (GCM) simulations to different future pathways of greenhouse gases, including rapid first-order assessments of how the land surface and associated biogeochemical cycles might change. Evaluation of how new terrestrial process understanding influences such predictions can also be made with relative ease.
- Published
- 2018
37. Comparison of stochastic parameterizations in the framework of a coupled ocean-atmosphere model
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Jonathan Demaeyer and Stéphane Vannitsem
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Cultural Studies ,Singular perturbation ,010504 meteorology & atmospheric sciences ,Computer science ,Gaussian ,FOS: Physical sciences ,Atmospheric model ,01 natural sciences ,Homogenization (chemistry) ,Markov operator ,010305 fluids & plasmas ,Education ,symbols.namesake ,0103 physical sciences ,Statistical physics ,lcsh:Science ,Condensed Matter - Statistical Mechanics ,0105 earth and related environmental sciences ,Statistical Mechanics (cond-mat.stat-mech) ,lcsh:QC801-809 ,Nonlinear Sciences - Chaotic Dynamics ,lcsh:QC1-999 ,Physics - Atmospheric and Oceanic Physics ,Intermediate complexity ,lcsh:Geophysics. Cosmic physics ,Atmospheric and Oceanic Physics (physics.ao-ph) ,symbols ,Probability distribution ,lcsh:Q ,Chaotic Dynamics (nlin.CD) ,lcsh:Physics - Abstract
A new framework is proposed for the evaluation of stochastic subgrid-scale parameterizations in the context of MAOOAM, a coupled ocean-atmosphere model of intermediate complexity. Two physically-based parameterizations are investigated, the first one based on the singular perturbation of Markov operator, also known as homogenization. The second one is a recently proposed parameterization based on the Ruelle's response theory. The two parameterization are implemented in a rigorous way, assuming however that the unresolved scale relevant statistics are Gaussian. They are extensively tested for a low-order version known to exhibit low-frequency variability, and some preliminary results are obtained for an intermediate-order version. Several different configurations of the resolved-unresolved scale separations are then considered. Both parameterizations show remarkable performances in correcting the impact of model errors, being even able to change the modality of the probability distributions. Their respective limitations are also discussed., Comment: 44 pages, 12 figures, 4 tables
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- 2018
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38. Human population dynamics in Europe over the Last Glacial Maximum
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Miska Luoto, Natalia Korhonen, Heikki Seppä, Miikka Tallavaara, Heikki Järvinen, Department of Philosophy, History and Art Studies, Department of Geosciences and Geography, Department of Physics, and INAR Physics
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1171 Geosciences ,demography ,Time Factors ,niche modeling ,Climate ,Climate Change ,Population Dynamics ,Population ,Social Sciences ,Climate change ,INTERMEDIATE COMPLEXITY ,hunter-gatherers ,ICE-SHEET MODEL ,114 Physical sciences ,Human population dynamics ,ARCTIC-CIRCLE ,Paleolithic ,Prehistoric demography ,Humans ,Population growth ,TEMPORAL FREQUENCY-DISTRIBUTIONS ,Computer Simulation ,Ice Cover ,Glacial period ,education ,Ecosystem ,LATE MOUSTERIAN PERSISTENCE ,Population Density ,education.field_of_study ,Multidisciplinary ,Geography ,Population size ,Last Glacial Maximum ,SPECIES DISTRIBUTION MODELS ,Models, Theoretical ,15. Life on land ,Adaptation, Physiological ,Biological Evolution ,PART I ,Europe ,13. Climate action ,Climatology ,1181 Ecology, evolutionary biology ,GENOME SEQUENCES ,PREHISTORIC DEMOGRAPHY ,HUMAN-EVOLUTION ,Algorithms - Abstract
The severe cooling and the expansion of the ice sheets during the Last Glacial Maximum (LGM), 27,000-19,000 y ago (27-19 ky ago) had a major impact on plant and animal populations, including humans. Changes in human population size and range have affected our genetic evolution, and recent modeling efforts have reaffirmed the importance of population dynamics in cultural and linguistic evolution, as well. However, in the absence of historical records, estimating past population levels has remained difficult. Here we show that it is possible to model spatially explicit human population dynamics from the pre-LGM at 30 ky ago through the LGM to the Late Glacial in Europe by using climate envelope modeling tools and modern ethnographic datasets to construct a population calibration model. The simulated range and size of the human population correspond significantly with spatiotemporal patterns in the archaeological data, suggesting that climate was a major driver of population dynamics 30-13 ky ago. The simulated population size declined from about 330,000 people at 30 ky ago to a minimum of 130,000 people at 23 ky ago. The Late Glacial population growth was fastest during Greenland interstadial 1, and by 13 ky ago, therewere almost 410,000 people in Europe. Even during the coldest part of the LGM, the climatically suitable area for human habitation remained unfragmented and covered 36% of Europe.
- Published
- 2015
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39. Impact of Sea Level Assimilation on ENSO Initialization and Prediction: The Role of the Sea Level Zonal Tilt and Zonal Mean
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Sulian Thual, Nadia Ayoub, and Boris Dewitte
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Atmospheric Science ,Intermediate complexity ,El Niño Southern Oscillation ,Data assimilation ,Simple Ocean Data Assimilation ,Climatology ,Initialization ,Ensemble Kalman filter ,Assimilation (biology) ,Atmospheric sciences ,Sea level - Abstract
At present, most models forecasting the El Niño–Southern Oscillation (ENSO) use data assimilation, which constrains models physics using available observations. In this article, an ENSO model of intermediate complexity is constrained by sea level observations: sea level from the Simple Ocean Data Assimilation (SODA) reanalysis is assimilated in the model forced by SODA winds, using an ensemble Kalman filter. In addition, retrospective ENSO forecasts over the period 1958–2007 are computed. The assimilation of sea level observations slightly improves the model’s predictive skill, which is due to the correction of the recharge–discharge process simulated by the model. To assess this, two indices relevant to the ENSO recharge–discharge theory are considered: the zonal tilt and zonal mean of sea level in the equatorial Pacific. The assimilation of those two observed indices alone leads to results that are qualitatively similar to the assimilation of full maps of sea level observations. This partly results from the fact that the leading statistical modes of the model errors on sea level have a zonal tilt and zonal mean structure. The data assimilation corrects in particular a too weak amplitude of the zonal mean sea level and its associated subsurface variability in the model. The authors suggest that insight on the role of the recharge–discharge process in other models could be gained by comparing the assimilation of full maps of sea level observations with the assimilation of the two indices of sea level.
- Published
- 2015
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40. Experiencia de las pacientes frente a citología cérvico-vaginal reportada como ASCUS o LEI de bajo grado en dos instituciones de Bogotá (Colombia), 2014
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Jairo Amaya-Guío, Yahira Rossini Guzmán-Sabogal, Solange Monsalve-Páez, Diana Valderrama-Vega, and Marcos Fidel Castillo-Zamora
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Cervical cancer ,Gynecology ,medicine.medical_specialty ,Investigación cualitativa ,business.industry ,citología ,Obstetrics and Gynecology ,Cervicovaginal cytology ,Atypical Squamous Cells ,respuesta emocional ,medicine.disease ,lcsh:Gynecology and obstetrics ,Abnormal cytology ,Surgery ,Intermediate complexity ,Citología ,Cytology ,Respuesta emocional ,Medicine ,Anxiety ,medicine.symptom ,investigación cualitativa ,business ,Ascus ,lcsh:RG1-991 - Abstract
Objetivo: describir los conocimientos que tienen las pacientes acerca del uso de la citología, y las emociones y el comportamiento que genera en estas un resultado positivo en la citología vaginal con atipias escamosas de significado indeterminado (ASCUS) o lesión escamosa intraepitelial de bajo grado (LEI-BG).Materiales y métodos: investigación cualitativa fenomenológica, que busca establecer las experiencias vividas por mujeres entre 18 y 69 años que consultaron por primera vez, por el hallazgo en la citología cérvico-vaginal de ASCUS o LEI-BG, a la unidad de patología cervical de dos instituciones de nivel medio de complejidad en Bogotá (Colombia), una institución pública y otra un centro de atención ambulatorio privado. El tamaño de la muestra se determinó por saturación teórica y muestreo consecutivo. Se realizaron grupos focales y entrevistas, la información fue grabada y transcrita posteriormente, creando categorías para evaluar las experiencias: caracterización sociodemográfica, cognición, características afectivas y comportamiento. Se empleó el estilo de análisis mediante edición, presentado como material narrativo, a fin de ordenar la información recolectada para su síntesis e interpretación.Resultados: se incluyeron 27 mujeres. El resultado anormal de la citología cérvico-vaginal despierta sentimientos de culpa, angustia y preocupación pues lo relacionan con el cáncer de cuello uterino, dado que no es claro para ellas que este es un examen de tamización. La principal conducta posterior a recibir el resultado de la citología fue priorizar la cita médica. Hay alteraciones en las relaciones de pareja basadas en la percepción de infidelidad secundaria a la infección de VPH.Conclusiones: la toma de la citología cérvico-vaginal es considerada por las pacientes como importantísima y obligatoria en el marco de la necesidad de prevenir y tratar el cáncer de cuello uterino.
- Published
- 2015
41. Data-driven localization mappings in filtering the monsoon-Hadley multicloud convective flows
- Author
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Michèle De La Chevrotière and John Harlim
- Subjects
Convection ,Atmospheric Science ,010504 meteorology & atmospheric sciences ,Computer science ,Kalman filter ,Monsoon ,Dynamical system ,01 natural sciences ,010305 fluids & plasmas ,Data-driven ,Intermediate complexity ,Physics - Atmospheric and Oceanic Physics ,Data assimilation ,0103 physical sciences ,Statistical physics ,Physics - Computational Physics ,0105 earth and related environmental sciences - Abstract
This paper demonstrates the efficacy of data-driven localization mappings for assimilating satellite-like observations in a dynamical system of intermediate complexity. In particular, a sparse network of synthetic brightness temperature measurements is simulated using an idealized radiative transfer model and assimilated to the monsoon-Hadley multicloud model, a nonlinear stochastic model containing several thousands of model coordinates. A serial ensemble Kalman filter is implemented in which the empirical correlation statistics are improved using localization maps obtained from a supervised learning algorithm. The impact of the localization mappings is assessed in perfect model observing system simulation experiments (OSSEs) as well as in the presence of model errors resulting from the misspecification of key convective closure parameters. In perfect model OSSEs, the localization mappings that use adjacent correlations to improve the correlation estimated from small ensemble sizes produce robust accurate analysis estimates. In the presence of model error, the filter skills of the localization maps trained on perfect and imperfect model data are comparable., Comment: monthly weather review (in press)
- Published
- 2017
42. An optimization strategy for identifying parameter sensitivity in atmospheric and oceanic models
- Author
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Wang, Qiang, Tang, Youmin, Dijkstra, Henk A., Sub Physical Oceanography, Dep Natuurkunde, Marine and Atmospheric Research, Sub Physical Oceanography, Dep Natuurkunde, and Marine and Atmospheric Research
- Subjects
Friction coefficient ,Optimization ,Atmospheric Science ,010504 meteorology & atmospheric sciences ,Meteorology ,Sensitivity studies ,010505 oceanography ,01 natural sciences ,Pacific ocean ,Nonlinear programming ,Numerical analysis/modeling ,Intermediate complexity ,Path (graph theory) ,Meander ,Environmental science ,Applied mathematics ,14. Life underwater ,Sensitivity (control systems) ,Physics::Atmospheric and Oceanic Physics ,0105 earth and related environmental sciences - Abstract
A new optimization strategy is proposed to identify the sensitivities of simulations of atmospheric and oceanic models to uncertain parameters. The strategy is based on a nonlinear optimization method that is able to estimate the maximum values of specific parameter sensitivity measures; meanwhile, it takes into account interactions among uncertain parameters. It is tested using the Lorenz’63 model and an intermediate complexity 2.5-layer shallow-water model of the North Pacific Ocean. For the Lorenz’63 model, it is shown that the parameter sensitivities of the model results depend on the initial conditions. For the 2.5-layer shallow-water model used to simulate the Kuroshio large meander (KLM) south of Japan, the optimization strategy reveals that the prediction of the KLM path is insensitive to the uncertainties in the bottom friction coefficient, the interfacial friction coefficient, and the lateral friction coefficient. Rather, the KLM prediction is relatively sensitive to the uncertainties of the reduced gravity representing ocean stratification and the wind stress coefficient.
- Published
- 2017
43. Enzyme Kinetics Modeling as a Tool to Optimize Food Industry: A Pragmatic Approach Based on Amylolytic Enzymes
- Author
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Charis M. Galanakis, Anna Patsioura, and Vassilis Gekas
- Subjects
Food industry ,Food Handling ,Stochastic modelling ,Computer science ,Industrial and Manufacturing Engineering ,Field (computer science) ,Environmental Biotechnology ,Αmylases ,Representation (mathematics) ,Monte Carlo ,Multienzyme kinetics ,Artificial neural network ,business.industry ,Empirical modelling ,General Medicine ,Models, Theoretical ,Michaelis–Menten ,Kinetics ,Intermediate complexity ,Νeural networks ,Amylases ,Engineering and Technology ,Εmpirical models ,Biochemical engineering ,business ,Algorithms ,Food Science - Abstract
Modeling is an important tool in the food industry since it is able to simplify explanation of phenomena and optimize processes that cover a broad field from manufacture to byproducts treatment. The goal of the current article is to explore the development of enzyme kinetic models and their evolution over the last decades. For this reason, corresponding simulations were classified in deterministic, empirical, and stochastic models, prior investigating limitations, corrections, and industrial applications in each case. The ultimate goal is to provide an answer to a major problem: how can we develop an intermediate complexity model that achieves satisfactorily representation of the main phenomena with a limited number of parameters?
- Published
- 2014
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44. The Fine Structure of Shape Tuning in Area V4
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Jude F. Mitchell, Tatyana O. Sharpee, John V. Reynolds, and Anirvan S. Nandy
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Neuroscience(all) ,Curvature ,Article ,03 medical and health sciences ,0302 clinical medicine ,Form perception ,medicine ,Animals ,Invariant (mathematics) ,Visual Cortex ,030304 developmental biology ,Physics ,0303 health sciences ,Communication ,Quantitative Biology::Neurons and Cognition ,business.industry ,General Neuroscience ,Local variation ,Macaca mulatta ,Translation invariance ,Form Perception ,Intermediate complexity ,Visual cortex ,medicine.anatomical_structure ,Pattern Recognition, Visual ,Receptive field ,Biological system ,business ,Photic Stimulation ,030217 neurology & neurosurgery - Abstract
SummaryPrevious studies have shown that neurons in area V4 are involved in the processing of shapes of intermediate complexity and are sensitive to curvature. These studies also suggest that curvature-tuned neurons are position invariant. We sought to examine the mechanisms that endow V4 neurons with these properties. Consistent with previous studies, we found that response rank order to the most- and least-preferred stimuli was preserved throughout the receptive field. However, a fine-grained analysis of shape tuning revealed a surprising result: V4 neurons tuned to highly curved shapes exhibit very limited translation invariance. At a fine spatial scale, these neurons exhibit local variation in orientation. In contrast, neurons that prefer straight contours exhibit spatially invariant orientation-tuning and homogenous fine-scale orientation maps. Both of these patterns are consistent with a simple orientation-pooling model, with tuning for straight or curved shapes resulting, respectively, from pooling of homogenous or heterogeneous orientation signals inherited from early visual areas.
- Published
- 2013
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45. The University of Victoria Cloud Feedback Emulator (UVic-CFE): cloud radiative feedbacks in an intermediate complexity model
- Author
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Andreas Schmittner and D. J. Ullman
- Subjects
Intermediate complexity ,Meteorology ,business.industry ,Radiative transfer ,Environmental science ,Cloud computing ,Atmospheric sciences ,business ,Cloud feedback ,Physics::Atmospheric and Oceanic Physics ,Physics::Geophysics - Abstract
The dominant source of inter-model differences in comprehensive global climate models (GCMs) are cloud radiative effects on Earth's energy budget. Intermediate complexity models, while able to run more efficiently, often lack cloud feedbacks. Here, we describe and evaluate a method for applying GCM-derived shortwave and longwave cloud feedbacks from 4xCO2 and Last Glacial Maximum experiments to the University of Victoria Earth System Climate Model. The method generally captures the spread in top-of-the-atmosphere radiative feedbacks between the original GCMs, which impacts the magnitude and spatial distribution of surface temperature changes and climate sensitivity. These results suggest that the method is suitable to incorporate multi-model cloud feedback uncertainties in ensemble simulations with a single intermediate complexity model.
- Published
- 2016
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- View/download PDF
46. Could artificial ocean alkalinization protect tropical coral ecosystems from ocean acidification?
- Author
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Andreas Oschlies, Ellias Y. Feng, Wolfgang Koeve, and David P. Keller
- Subjects
0106 biological sciences ,South china ,010504 meteorology & atmospheric sciences ,Coral ,ocean acidification ,engineering.material ,01 natural sciences ,geoengineering ,Ecosystem ,Earth system model ,14. Life underwater ,0105 earth and related environmental sciences ,General Environmental Science ,Renewable Energy, Sustainability and the Environment ,010604 marine biology & hydrobiology ,Aragonite ,Public Health, Environmental and Occupational Health ,Ocean acidification ,Great barrier reef ,Intermediate complexity ,Oceanography ,13. Climate action ,engineering ,climate engineering ,Environmental science ,coral reef ,weathering enhancement ,ocean alkalinization - Abstract
Artificial ocean alkalinization (AOA) is investigated as a method to mitigate local ocean acidification and protect tropical coral ecosystems during a 21st century high CO2 emission scenario. Employing an Earth system model of intermediate complexity, our implementation of AOA in the Great Barrier Reef, Caribbean Sea and South China Sea regions, shows that alkalinization has the potential to counteract expected 21st century local acidification in regard to both oceanic surface aragonite saturation Omega and surface pCO(2). Beyond preventing local acidification, regional AOA, however, results in locally elevated aragonite oversaturation and pCO(2) decline. A notable consequence of stopping regional AOA is a rapid shift back to the acidified conditions of the target regions. We conclude that AOA may be a method that could help to keep regional coral ecosystems within saturation states and pCO(2) values close to present-day values even in a high-emission scenario and thereby might 'buy some time' against the ocean acidification threat, even though regional AOA does not significantly mitigate the warming threat.
- Published
- 2016
47. AMOC-emulator M-AMOC1.0 for uncertainty assessment of future projections
- Author
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Andreas Schmittner, Pepijn Johannes Bakker, and Earth and Climate
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Box model ,010504 meteorology & atmospheric sciences ,Global warming ,Greenland ice sheet ,Climate change ,010502 geochemistry & geophysics ,01 natural sciences ,Intermediate complexity ,General Circulation Model ,Climatology ,SDG 13 - Climate Action ,Environmental science ,Sensitivity (control systems) ,0105 earth and related environmental sciences - Abstract
State-of-the-science global climate models show that global warming is likely to weaken the Atlantic Meridional Overturning Circulation (AMOC). While such models are arguably the best tools to perform AMOC projections, they do not allow a comprehensive uncertainty assessment because of limited computational resources. Here we present an AMOC-emulator, a box model with a number of free parameters that can be tuned to mimic the sensitivity of the AMOC to climate change of a specific global climate model. The AMOC-emulator (M-AMOC1.0) is applied to simulations of global warming and melting of the Greenland Ice Sheet, performed with an intermediate complexity model. Predictive power of the AMOC-emulator is shown by comparison with a number of additional warming and Greenland Ice Sheet melt scenario that have not been used in the tuning of the AMOC-emulator, highlighting the potential of the AMOC-emulator to assess the uncertainty in AMOC projections.
- Published
- 2016
- Full Text
- View/download PDF
48. State-Dependence of the Climate Sensitivity in Earth System Models of Intermediate Complexity
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Thomas F. Stocker and Patrik L. Pfister
- Subjects
geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Extrapolation ,Magnitude (mathematics) ,Forcing (mathematics) ,010502 geochemistry & geophysics ,Atmospheric sciences ,01 natural sciences ,Earth system science ,Intermediate complexity ,Geophysics ,Climatology ,Sea ice ,General Earth and Planetary Sciences ,Climate sensitivity ,State dependence ,Environmental science ,0105 earth and related environmental sciences - Abstract
Growing evidence from general circulation models (GCMs) indicates that the equilibrium climate sensitivity (ECS) depends on the magnitude of forcing, which is commonly referred to as state-dependence. We present a comprehensive assessment of ECS state-dependence in Earth system models of intermediate complexity (EMICs) by analyzing millennial simulations with sustained 2×CO₂ and 4×CO₂ forcings. We compare different extrapolation methods and show that ECS is smaller in the higher-forcing scenario in 12 out of 15 EMICs, in contrast to the opposite behavior reported from GCMs. In one such EMIC, the Bern3D-LPX model, this state-dependence is mainly due to the weakening sea ice-albedo feedback in the Southern Ocean, which depends on model configuration. Due to ocean-mixing adjustments, state-dependence is only detected hundreds of years after the abrupt forcing, highlighting the need for long model integrations. Adjustments to feedback parametrizations of EMICs may be necessary if GCM intercomparisons confirm an opposite state-dependence.
- Published
- 2017
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49. Modelagem do Impacto da Topografia Boreal no Clima Global (Modelling the Impact of Topography on Global Climate Boreal)
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Bruno Lopes de Faria and Flávio Barbosa Justino
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Hydrology ,lcsh:GE1-350 ,Atmospheric Science ,Global climate ,Geography, Planning and Development ,Climate change ,Intermediate complexity ,Geophysics ,Geography ,Boreal ,Air temperature ,Topografia, Mudanças Climáticas, Modelos Climáticos ,Climate model ,Computers in Earth Sciences ,lcsh:GB3-5030 ,Geomorphology ,lcsh:Physical geography ,lcsh:Environmental sciences ,Earth-Surface Processes ,General Environmental Science - Abstract
Foram realizadas simulacoes climaticas a partir de 2 experimentos de sensibilidade numerica conduzidos com um modelo acoplado de complexidade intermediaria, LOVECLIM , estendendo-se para um periodo de 300 anos. Sendo que, neste experimento foi realizada a reducao em 50% da topografia geral do hemisferio norte, um com modelo acoplado (oceano-atmosfera) e outro desacoplado (somente atmosfera). Nos resultados obtidos, foram observadas alteracoes no padrao de clima global e local, em especial a regiao da Asia, relacionadas com aumento de temperatura do ar a superficie e intensidade do vento. Maiores alteracoes foram observados em regioes continentais no hemisferio norte. Isto mostra o maior impacto local causado pela forcante topografica com o a reducao da pela metade da topografia boreal. Palavras-chave : Topografia, Mudancas Climaticas, Modelos Climaticos, Forcante Climatica Modelling the Impact of Topography on Global Climate Boreal ABSTRACT Simulations were conducted from two numerical sensitivity experiments conducted with a coupled model with intermediate complexity, LOVECLIM, extending for a period of 300 years. Since this experiment was carried out 50% reduction in the general topography of the northern hemisphere, with a coupled model (ocean-atmosphere) and the other uncoupled (atmosphere only). Their results have been observed changes in the pattern of global and local climate, particularly in Asia, linked to increase of air temperature and wind intensity. The biggest impacts were observed in continental regions in the north hemisphere. This shows the greater local impact caused by topographic forcing Keywords : Topography, Climate Change, Climate Models, Topographic Forcing
- Published
- 2011
50. Ultra-high resolution pollen record from the northern Andes reveals rapid shifts in montane climates within the last two glacial cycles
- Author
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W. Westerhoff, L. Contreras, J. van der Plicht, Henry Hooghiemstra, A. Betancourt, M. Vriend, Martin Ziegler, Juan Carlos Berrio, Sergio Gaviria, D. Ortega, O. Rangel, S. L. Weber, E. Tuenter, M. van der Linden, Catalina Giraldo, N. González, B. van Geel, T. van der Hammen, Jef Vandenberghe, J. H. F. Jansen, Gustavo Sarmiento, M.H.M. Groot, Martin Konert, R. G. Bogotá, Lucas Joost Lourens, Isotope Research, Paleoecology and Landscape Ecology (IBED, FNWI), Earth and Climate, and Climate Change and Landscape Dynamics
- Subjects
Marine isotope stage ,010506 paleontology ,Arboreal locomotion ,010504 meteorology & atmospheric sciences ,PAST 800,000 YEARS ,Aardwetenschappen ,Stratigraphy ,lcsh:Environmental protection ,TIME-SERIES ,INTERMEDIATE COMPLEXITY ,Forcing (mathematics) ,medicine.disease_cause ,GREENLAND ICE ,01 natural sciences ,Isotopes of oxygen ,000 YEARS ,lcsh:Environmental pollution ,Pollen ,GRIP ICE CORE ,medicine ,lcsh:TD169-171.8 ,Glacial period ,lcsh:Environmental sciences ,0105 earth and related environmental sciences ,lcsh:GE1-350 ,Global and Planetary Change ,OCEAN-ATMOSPHERE SYSTEM ,PAST 800 ,Elevation ,Paleontology ,Vegetation ,15. Life on land ,MILLENNIAL-SCALE ,TEMPERATURE-VARIATIONS ,13. Climate action ,Climatology ,EASTERN-CORDILLERA ,lcsh:TD172-193.5 ,TRANSIENT SIMULATION ,Geology - Abstract
Here we developed a composite pollen-based record of altitudinal vegetation changes from Lake Fúquene (5° N) in Colombia at 2540 m elevation. We quantitatively calibrated Arboreal Pollen percentages (AP%) into mean annual temperature (MAT) changes with an unprecedented ~60-year resolution over the past 284 000 years. An age model for the AP% record was constructed using frequency analysis in the depth domain and tuning of the distinct obliquity-related variations to the latest marine oxygen isotope stacked record. The reconstructed MAT record largely concurs with the ~100 and 41-kyr (obliquity) paced glacial cycles and is superimposed by extreme changes of up to 7 to 10° Celsius within a few hundred years at the major glacial terminations and during marine isotope stage 3, suggesting an unprecedented North Atlantic – equatorial link. Using intermediate complexity transient climate modelling experiments, we demonstrate that ice volume and greenhouse gasses are the major forcing agents causing the orbital-related MAT changes, while direct precession-induced insolation changes had no significant impact on the high mountain vegetation during the last two glacial cycles.
- Published
- 2011
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