45 results on '"John M Lyman"'
Search Results
2. CERESMIP: a climate modeling protocol to investigate recent trends in the Earth's Energy Imbalance
- Author
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Gavin A. Schmidt, Timothy Andrews, Susanne E. Bauer, Paul J. Durack, Norman G. Loeb, V. Ramaswamy, Nathan P. Arnold, Michael G. Bosilovich, Jason Cole, Larry W. Horowitz, Gregory C. Johnson, John M. Lyman, Brian Medeiros, Takuro Michibata, Dirk Olonscheck, David Paynter, Shiv Priyam Raghuraman, Michael Schulz, Daisuke Takasuka, Vijay Tallapragada, Patrick C. Taylor, and Tilo Ziehn
- Subjects
CMIP6 ,climate modeling ,earth's energy balance ,aerosols ,cloud feedbacks ,AMIP ,Environmental sciences ,GE1-350 - Abstract
The Clouds and the Earth's Radiant Energy System (CERES) project has now produced over two decades of observed data on the Earth's Energy Imbalance (EEI) and has revealed substantive trends in both the reflected shortwave and outgoing longwave top-of-atmosphere radiation components. Available climate model simulations suggest that these trends are incompatible with purely internal variability, but that the full magnitude and breakdown of the trends are outside of the model ranges. Unfortunately, the Coupled Model Intercomparison Project (Phase 6) (CMIP6) protocol only uses observed forcings to 2014 (and Shared Socioeconomic Pathways (SSP) projections thereafter), and furthermore, many of the ‘observed' drivers have been updated substantially since the CMIP6 inputs were defined. Most notably, the sea surface temperature (SST) estimates have been revised and now show up to 50% greater trends since 1979, particularly in the southern hemisphere. Additionally, estimates of short-lived aerosol and gas-phase emissions have been substantially updated. These revisions will likely have material impacts on the model-simulated EEI. We therefore propose a new, relatively low-cost, model intercomparison, CERESMIP, that would target the CERES period (2000-present), with updated forcings to at least the end of 2021. The focus will be on atmosphere-only simulations, using updated SST, forcings and emissions from 1990 to 2021. The key metrics of interest will be the EEI and atmospheric feedbacks, and so the analysis will benefit from output from satellite cloud observation simulators. The Tier 1 request would consist only of an ensemble of AMIP-style simulations, while the Tier 2 request would encompass uncertainties in the applied forcing, atmospheric composition, single and all-but-one forcing responses. We present some preliminary results and invite participation from a wide group of models.
- Published
- 2023
- Full Text
- View/download PDF
3. Evaluating Twenty-Year Trends in Earth’s Energy Flows from Observations and Reanalyses
- Author
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Norman G Loeb, Michael Mayer, Seiji Kato, John T Fasullo, Hao Zuo, Retish Senan, John M Lyman, Gregory C Johnson, and Magdalena Balmaseda
- Subjects
Earth Resources And Remote Sensing - Abstract
Satellite, reanalysis, and ocean in situ data are analyzed to evaluate regional, hemispheric and global mean trends in Earth’s energy fluxes during the first twenty years of the 21st century. Regional trends in net top-of-atmosphere (TOA) radiation from the Clouds and the Earth’s Radiant Energy System (CERES), ECMWF Reanalysis 5 (ERA5), and a model similar to ERA5 with prescribed sea surface temperature (SST) and sea ice differ markedly, particularly over the Eastern Pacific Ocean, where CERES observes large positive trends. Hemispheric and global mean net TOA flux trends for the two reanalyses are smaller than CERES, and their climatological means are half those of CERES in the southern hemisphere (SH) and more than nine times larger in the northern hemisphere (NH). The regional trend pattern of the divergence of total atmospheric energy transport (TEDIV) over ocean determined using ERA5 analyzed fields is similar to that inferred from the difference between TOA and surface fluxes from ERA5 short-term forecasts. There is also agreement in the trend pattern over ocean for surface fluxes inferred as a residual between CERES net TOA flux and ERA5 analysis TEDIV and surface fluxes obtained directly from ERA5 forecasts. Robust trends are observed over the Gulf Stream associated with enhanced surface-to-atmosphere transfer of heat. Within the ocean, larger trends in ocean heating rate are found in the NH than the SH after 2005, but the magnitude of the trend varies greatly among datasets.
- Published
- 2022
- Full Text
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4. Global High-Resolution Random Forest Regression Maps of Ocean Heat Content Anomalies Using In Situ and Satellite Data
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John M. Lyman and Gregory C. Johnson
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Atmospheric Science ,Ocean Engineering - Abstract
The ocean, with its low albedo and vast thermal inertia, plays key roles in the climate system, including absorbing massive amounts of heat as atmospheric greenhouse gas concentrations rise. While the Argo array of profiling floats has vastly improved sampling of ocean temperature in the upper half of the global ocean volume since the mid-2000s, they are not sufficient in number to resolve eddy scales in the oceans. However, satellite sea surface temperature (SST) and sea surface height (SSH) measurements do resolve these scales. Here we use random forest regressions to map ocean heat content anomalies (OHCA) using in situ training data from Argo and other sources on a 7-day × 1/4° × 1/4° grid with latitude, longitude, time, SSH, and SST as predictors. The maps display substantial patterns on eddy scales, resolving variations of ocean currents and fronts. During the well-sampled Argo period, global integrals of these maps reduce noise relative to estimates based on objective mapping of in situ data alone by roughly a factor of 3 when compared to time series of CERES (satellite data) top-of-the-atmosphere energy flux measurements and improve correlations of anomalies with CERES on annual time scales. Prior to and early on in the Argo period, when in situ data were sparser, global integrals of these maps retain low variance, and do not relax back to a climatological mean, avoiding potential deficiencies of various methods for infilling data-sparse regions with objective maps by exploiting temporal and spatial patterns of OHCA and its correlations with SST and SSH. Significance Statement We use a simple machine learning technique to improve maps of subsurface ocean warming by exploiting the relationships between subsurface ocean temperature both sea surface temperature and sea level. Mapping ocean warming is important because it contributes to sea level rise through thermal expansion; impacts marine life through marine heatwaves and changes in mixing, oxygen, and carbon dioxide levels; increases energy available to tropical cyclones; and stores most of the energy building up in Earth’s climate system owing to the accumulation of anthropogenic greenhouse gases in the atmosphere. Our new estimates generally have lower noise energy and higher correlations than other products when compared with global energy fluxes at the top of the atmosphere measured by satellite.
- Published
- 2023
5. State of the Climate in 2020: Global Oceans
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Gregory C Johnson, Rick Lumpkin, Simone R Alin, Dillon J Amaya, Molly O Baringer, Tim Boyer, Peter Brandt, Brendan R Carter, Ivona Cetinić, Don P Chambers, Lijing Cheng, Andrew U Collins, Cathy Cosca, Ricardo Domingues, Shenfu Dong, Richard A Feely, Eleanor Frajka-Williams, Bryan A Franz, John Gilson, Gustavo Goni, Benjamin D Hamlington, Josefine Herrford, Zeng-Zhen Hu, Boyin Huang, Masayoshi Ishii, Svetlana Jevrejeva, John J Kennedy, Marion Kersalé, Rachel E Killick, Peter Landschützer, Matthias Lankhorst, Eric Leuliette, Ricardo Locarnini, John M Lyman, John J Marra, Christopher S Meinen, Mark A Merrifield, Gary T Mitchum, Ben I Moat, R Steven Nerem, Renellys C Perez, Sarah G Purkey, James Reagan, Alejandra Sanchez-Franks, Hillary A Scannell, Claudia Schmid, Joel P Scott, David A Siegel, David A Smeed, Paul W Stackhouse, William Sweet, Philip R Thompson, Joaquin A Triñanes, Denis L Volkov, Rik Wanninkhof, Robert A Weller, Caihong Wen, Toby K Westberry, Matthew J Widlansky, Anne C Wilber, Lisan Yu, and Huai-Min Zhang
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Meteorology and Climatology - Abstract
This chapter details 2020 global patterns in select observed oceanic physical, chemical, and biological variables relative to long-term climatologies, their differences between 2020 and 2019, and puts 2020 observations in the context of the historical record. In this overview we address a few of the highlights, first in haiku, then paragraph form: La Niña arrives, shifts winds, rain, heat, salt, carbon: Pacific—beyond. Compiled by NOAA’s National Centers for Environmental Information, "State of the Climate in 2020" is based on contributions from scientists from around the world. It provides a detailed update on global climate indicators, notable weather events, and other data collected by environmental monitoring stations and instruments located on land, water, ice, and in space. The full report is available from: https://doi.org/10.1175/2021BAMSStateoftheClimate.1.
- Published
- 2021
- Full Text
- View/download PDF
6. Argo Data 1999–2019: Two Million Temperature-Salinity Profiles and Subsurface Velocity Observations From a Global Array of Profiling Floats
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Annie P. S. Wong, Susan E. Wijffels, Stephen C. Riser, Sylvie Pouliquen, Shigeki Hosoda, Dean Roemmich, John Gilson, Gregory C. Johnson, Kim Martini, David J. Murphy, Megan Scanderbeg, T. V. S. Udaya Bhaskar, Justin J. H. Buck, Frederic Merceur, Thierry Carval, Guillaume Maze, Cécile Cabanes, Xavier André, Noé Poffa, Igor Yashayaev, Paul M. Barker, Stéphanie Guinehut, Mathieu Belbéoch, Mark Ignaszewski, Molly O'Neil Baringer, Claudia Schmid, John M. Lyman, Kristene E. McTaggart, Sarah G. Purkey, Nathalie Zilberman, Matthew B. Alkire, Dana Swift, W. Brechner Owens, Steven R. Jayne, Cora Hersh, Pelle Robbins, Deb West-Mack, Frank Bahr, Sachiko Yoshida, Philip J. H. Sutton, Romain Cancouët, Christine Coatanoan, Delphine Dobbler, Andrea Garcia Juan, Jerôme Gourrion, Nicolas Kolodziejczyk, Vincent Bernard, Bernard Bourlès, Hervé Claustre, Fabrizio D'Ortenzio, Serge Le Reste, Pierre-Yve Le Traon, Jean-Philippe Rannou, Carole Saout-Grit, Sabrina Speich, Virginie Thierry, Nathalie Verbrugge, Ingrid M. Angel-Benavides, Birgit Klein, Giulio Notarstefano, Pierre-Marie Poulain, Pedro Vélez-Belchí, Toshio Suga, Kentaro Ando, Naoto Iwasaska, Taiyo Kobayashi, Shuhei Masuda, Eitarou Oka, Kanako Sato, Tomoaki Nakamura, Katsunari Sato, Yasushi Takatsuki, Takashi Yoshida, Rebecca Cowley, Jenny L. Lovell, Peter R. Oke, Esmee M. van Wijk, Fiona Carse, Matthew Donnelly, W. John Gould, Katie Gowers, Brian A. King, Stephen G. Loch, Mary Mowat, Jon Turton, E. Pattabhi Rama Rao, M. Ravichandran, Howard J. Freeland, Isabelle Gaboury, Denis Gilbert, Blair J. W. Greenan, Mathieu Ouellet, Tetjana Ross, Anh Tran, Mingmei Dong, Zenghong Liu, Jianping Xu, KiRyong Kang, HyeongJun Jo, Sung-Dae Kim, and Hyuk-Min Park
- Subjects
global ,ocean ,pressure ,temperature ,salinity ,Argo ,Science ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
In the past two decades, the Argo Program has collected, processed, and distributed over two million vertical profiles of temperature and salinity from the upper two kilometers of the global ocean. A similar number of subsurface velocity observations near 1,000 dbar have also been collected. This paper recounts the history of the global Argo Program, from its aspiration arising out of the World Ocean Circulation Experiment, to the development and implementation of its instrumentation and telecommunication systems, and the various technical problems encountered. We describe the Argo data system and its quality control procedures, and the gradual changes in the vertical resolution and spatial coverage of Argo data from 1999 to 2019. The accuracies of the float data have been assessed by comparison with high-quality shipboard measurements, and are concluded to be 0.002°C for temperature, 2.4 dbar for pressure, and 0.01 PSS-78 for salinity, after delayed-mode adjustments. Finally, the challenges faced by the vision of an expanding Argo Program beyond 2020 are discussed.
- Published
- 2020
- Full Text
- View/download PDF
7. Ocean Warming: From the Surface to the Deep in Observations and Models
- Author
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Paul J. Durack, Peter J. Gleckler, Sarah G. Purkey, Gregory C. Johnson, John M. Lyman, and Tim P. Boyer
- Subjects
ocean warming ,global climate system ,greenhouse gas ,Oceanography ,GC1-1581 - Abstract
The ocean is the primary heat sink of the global climate system. Since 1971, it has been responsible for storing more than 90% ofthe excess heat added to the Earth system by anthropogenic greenhouse-gas emissions. Adding this heat to the ocean contributes substantially to sea level rise and affects vital marine ecosystems. Considering the global ocean’s large role in ongoing climate variability and change, it is a good place to focus in order to understand what observed changes have occurred to date and, by using models, what future changes might arise under continued anthropogenic forcing of the climate system. While sparse measurement coverage leads to enhanced uncertainties with long-term historical estimates of change, modern measurements are beginning to provide the clearest picture yet of ongoing global ocean change. Observations show that the ocean is warming from the near-surface through to the abyss, a conclusion that is strengthened with each new analysis. In this assessment, we revisit observation- and model-based estimates of ocean warming from the industrial era to the present and show a consistent, full-depth pattern of change over the observed record that is likely to continue at an ever-increasing pace if effective actions to reduce greenhouse-gas emissions are not taken.
- Published
- 2018
- Full Text
- View/download PDF
8. Global Oceans
- Author
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Gregory C. Johnson, Rick Lumpkin, Tim Boyer, Francis Bringas, Ivona Cetinić, Don P. Chambers, Lijing Cheng, Shenfu Dong, Richard A. Feely, Baylor Fox-Kemper, Eleanor Frajka-Williams, Bryan A. Franz, Yao Fu, Meng Gao, Jay Garg, John Gilson, Gustavo Goni, Benjamin D. Hamlington, Helene T. Hewitt, William R. Hobbs, Zeng-Zhen Hu, Boyin Huang, Svetlana Jevrejeva, William E. Johns, Sato Katsunari, John J. Kennedy, Marion Kersalé, Rachel E. Killick, Eric Leuliette, Ricardo Locarnini, M. Susan Lozier, John M. Lyman, Mark A. Merrifield, Alexey Mishonov, Gary T. Mitchum, Ben I. Moat, R. Steven Nerem, Dirk Notz, Renellys C. Perez, Sarah G. Purkey, Darren Rayner, James Reagan, Claudia Schmid, David A. Siegel, David A. Smeed, Paul W. Stackhouse, William Sweet, Philip R. Thompson, Denis L. Volkov, Rik Wanninkhof, Robert A. Weller, Caihong Wen, Toby K. Westberry, Matthew J. Widlansky, Josh K. Willis, Lisan Yu, and Huai-Min Zhang
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Atmospheric Science - Published
- 2022
9. Global Oceans
- Author
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T. C. Lee, A. Sanchez-Franks, Lijing Cheng, David A. Smeed, Boyin Huang, Bryan A. Franz, Ben Moat, Uwe Send, M.B. Bif, S.M. Bushinsky, Y. Takeshita, John M. Lyman, Matthew J. Widlansky, Deborah J. Misch, Jessicca Griffin, William Sweet, E. Frajka-Williams, Eric Leuliette, R.S. Nerem, Matthias Lankhorst, Catia M. Domingues, Masayoshi Ishii, Paul W. Stackhouse, Toby K. Westberry, James Reagan, John J. Marra, Ricardo A. Locarnini, N. Rome, Denis Volkov, Shenfu Dong, Philip R. Thompson, Sara W. Veasey, Timothy P. Boyer, Robert A. Weller, Zeng-Zhen Hu, Claudia Schmid, Gustavo Goni, Christopher S. Meinen, Rick Lumpkin, Lisan Yu, Ivona Cetinić, A. Andersen, S.E. Love-Brotak, Didier Monselesan, Rik Wanninkhof, Kenneth S. Johnson, Don P. Chambers, Svetlana Jevrejeva, A.J. Fassbender, Merrifield, William E. Johns, Anne C. Wilber, Brendan R. Carter, John Kennedy, David A. Siegel, Darren Rayner, Molly O. Baringer, M. Visbeck, Joaquin Trinanes, J.P. Scott, Gregory Hammer, Deborah B. Riddle, Benjamin D. Hamlington, John Gilson, W. Yu, M. Dai, Sarah G. Purkey, Gregory C. Johnson, Gary T. Mitchum, S. Speich, F. Li, Susan Wijffels, Rachel Killick, M. Kersalé, E. Lindstrom, S. Chiba, Richard A. Feely, R.C. Perez, Peter Landschützer, S. Lozier, and Huai Min Zhang
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Atmospheric Science ,010504 meteorology & atmospheric sciences ,State (polity) ,Climatology ,media_common.quotation_subject ,0211 other engineering and technologies ,Environmental science ,02 engineering and technology ,01 natural sciences ,021101 geological & geomatics engineering ,0105 earth and related environmental sciences ,media_common - Abstract
State of the climate in 2019
- Published
- 2020
10. Warming trends increasingly dominate global ocean
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John M. Lyman and Gregory C. Johnson
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0303 health sciences ,Research groups ,010504 meteorology & atmospheric sciences ,Effects of global warming on oceans ,Global warming ,Environmental Science (miscellaneous) ,Physical oceanography ,01 natural sciences ,03 medical and health sciences ,Sea surface temperature ,Climatology ,Period (geology) ,Environmental science ,Ocean heat content ,Social Sciences (miscellaneous) ,Pacific decadal oscillation ,030304 developmental biology ,0105 earth and related environmental sciences - Abstract
The ocean takes up about 93% of the global warming heat entering Earth’s climate system. In addition, the associated thermal expansion contributes substantially to sea-level rise. Hence, quantifying the oceanic heat uptake rate and its statistical significance has been a research focus. Here we use gridded ocean heat content maps to examine regional trends in ocean warming for 0–700 m depth from 1993–2019 and 1968–2019, periods based on sampling distributions. The maps are from four research groups, three based on ocean temperature alone and one combining ocean temperature with satellite altimeter sea-level anomalies. We show that use of longer periods results in larger percentages of ocean area with statistically significant warming trends and less ocean area covered by statistically significant cooling trends. We discuss relations of these patterns to climate phenomena, including the Pacific Decadal Oscillation, the Atlantic Meridional Overturning Circulation and global warming. A large proportion of anthropogenic heat energy is being taken up by ocean warming. Analysis of yearly 0–700 m ocean heat content maps from four different estimates shows that the longer the period over which regional trends are estimated, the larger the area of statistically significant warming.
- Published
- 2020
11. Quantifying Spread in Spatiotemporal Changes of Upper-Ocean Heat Content Estimates: An Internationally Coordinated Comparison
- Author
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Timothy P. Boyer, Will Hobbs, Rebecca Cowley, Susan Wijffels, Simon J. Marsland, Abhishek Savita, John M. Lyman, Josh K. Willis, Masayoshi Ishii, John A. Church, Viktor Gouretski, Didier Monselesan, Gregory C. Johnson, Catia M. Domingues, and Peter Dobrohotoff
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Earth system science ,Atmospheric Science ,Indian ocean ,Research groups ,Frontal regions ,Climatology ,Anomaly (natural sciences) ,Environmental science ,Ocean heat content ,Bathythermograph ,Pacific ocean - Abstract
The Earth system is accumulating energy due to human-induced activities. More than 90% of this energy has been stored in the ocean as heat since 1970, with ∼60% of that in the upper 700 m. Differences in upper-ocean heat content anomaly (OHCA) estimates, however, exist. Here, we use a dataset protocol for 1970–2008—with six instrumental bias adjustments applied to expendable bathythermograph (XBT) data, and mapped by six research groups—to evaluate the spatiotemporal spread in upper OHCA estimates arising from two choices: 1) those arising from instrumental bias adjustments and 2) those arising from mathematical (i.e., mapping) techniques to interpolate and extrapolate data in space and time. We also examined the effect of a common ocean mask, which reveals that exclusion of shallow seas can reduce global OHCA estimates up to 13%. Spread due to mapping method is largest in the Indian Ocean and in the eddy-rich and frontal regions of all basins. Spread due to XBT bias adjustment is largest in the Pacific Ocean within 30°N–30°S. In both mapping and XBT cases, spread is higher for 1990–2004. Statistically different trends among mapping methods are found not only in the poorly observed Southern Ocean but also in the well-observed northwest Atlantic. Our results cannot determine the best mapping or bias adjustment schemes, but they identify where important sensitivities exist, and thus where further understanding will help to refine OHCA estimates. These results highlight the need for further coordinated OHCA studies to evaluate the performance of existing mapping methods along with comprehensive assessment of uncertainty estimates.
- Published
- 2022
12. GOSML: A Global Ocean Surface Mixed Layer Statistical Monthly Climatology: Means, Percentiles, Skewness, and Kurtosis
- Author
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Gregory C. Johnson and John M. Lyman
- Subjects
Geophysics ,Space and Planetary Science ,Geochemistry and Petrology ,Earth and Planetary Sciences (miscellaneous) ,Oceanography - Published
- 2022
13. Equatorial Pacific 1,000‐dbar Velocity and Isotherm Displacements From Argo Data: Beyond the Mean and Seasonal Cycle
- Author
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John M. Lyman, Hannah Zanowski, and Gregory C. Johnson
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Geophysics ,Space and Planetary Science ,Geochemistry and Petrology ,Climatology ,Earth and Planetary Sciences (miscellaneous) ,Rossby wave ,Oceanography ,Seasonal cycle ,Argo ,Geology - Published
- 2019
14. Global Oceans
- Author
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Gregory C. Johnson, Rick Lumpkin, Simone R. Alin, Dillon J. Amaya, Molly O. Baringer, Tim Boyer, Peter Brandt, Brendan R. Carter, Ivona Cetinić, Don P. Chambers, Lijing Cheng, Andrew U. Collins, Cathy Cosca, Ricardo Domingues, Shenfu Dong, Richard A. Feely, Eleanor Frajka-Williams, Bryan A. Franz, John Gilson, Gustavo Goni, Benjamin D. Hamlington, Josefine Herrford, Zeng-Zhen Hu, Boyin Huang, Masayoshi Ishii, Svetlana Jevrejeva, John J. Kennedy, Marion Kersalé, Rachel E. Killick, Peter Landschützer, Matthias Lankhorst, Eric Leuliette, Ricardo Locarnini, John M. Lyman, John J. Marra, Christopher S. Meinen, Mark A. Merrifield, Gary T. Mitchum, Ben I. Moat, R. Steven Nerem, Renellys C. Perez, Sarah G. Purkey, James Reagan, Alejandra Sanchez-Franks, Hillary A. Scannell, Claudia Schmid, Joel P. Scott, David A. Siegel, David A. Smeed, Paul W. Stackhouse, William Sweet, Philip R. Thompson, Joaquin A. Triñanes, Denis L. Volkov, Rik Wanninkhof, Robert A. Weller, Caihong Wen, Toby K. Westberry, Matthew J. Widlansky, Anne C. Wilber, Lisan Yu, and Huai-Min Zhang
- Subjects
Atmospheric Science - Published
- 2021
15. Satellite and Ocean Data Reveal Marked Increase in Earth’s Heating Rate
- Author
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Seiji Kato, John M. Lyman, Fred G. Rose, Norman G. Loeb, Gregory C. Johnson, and Tyler J. Thorsen
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Geophysics ,Meteorology ,General Earth and Planetary Sciences ,Environmental science ,Satellite ,Earth (classical element) - Published
- 2021
16. Subsurface Evolution and Persistence of Marine Heatwaves in the Northeast Pacific
- Author
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John M. Lyman, Gregory C. Johnson, Hillary A. Scannell, Stephen C. Riser, and LuAnne Thompson
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Geophysics ,Oceanography ,010504 meteorology & atmospheric sciences ,General Earth and Planetary Sciences ,Environmental science ,010502 geochemistry & geophysics ,01 natural sciences ,Pacific ocean ,The Blob ,Argo ,0105 earth and related environmental sciences ,Late summer - Abstract
The reappearance of a northeast Pacific marine heatwave (MHW) sounded alarms in late summer 2019 for a warming event on par with the 2013–2016 MHW known as The Blob. Despite these two events having...
- Published
- 2020
17. Subsurface Evolution and Persistence of Marine Heatwaves in the Northeast Pacific
- Author
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Hillary A. Scannell, Gregory C. Johnson, LuAnne Thompson, John M. Lyman, and Stephen C. Riser
- Published
- 2020
18. Antarctic Bottom Water Warming in the Brazil Basin: 1990s Through 2020, From WOCE to Deep Argo
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Gregory C. Johnson, Chanelle Cadot, Kristene E. McTaggart, John M. Lyman, and Elizabeth L. Steffen
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Geophysics ,Oceanography ,Antarctic Bottom Water ,Effects of global warming on oceans ,General Earth and Planetary Sciences ,Structural basin ,Argo ,Geology - Published
- 2020
19. Heat stored in the Earth system: Where does the energy go? The GCOS Earth heat inventory team
- Author
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Didier Monselesan, John Gilson, Almudena García-García, Masayoshi Ishii, Valentin Aich, Leopold Haimberger, Hugo Beltrami, Sarah G. Purkey, Gregory C. Johnson, Rachel Killik, John M. Lyman, Michael Mayer, Timothy P. Boyer, Pierre Gentine, Ben Marzeion, Nicolas Kolodziejczyk, Fiammetta Straneo, Caterina Tassone, Matthew D. Palmer, Dean Roemmich, Susan Wijffels, Catia M. Domingues, Mary-Louise Timmermans, Gottfried Kirchengast, Francisco José Cuesta-Valero, Donald Slater, Karina von Schuckmann, Damien Desbruyères, Maximilian Gorfer, Susheel Adusumilli, Axel Schweiger, Sonia I. Seneviratne, Brian A. King, Lijing Cheng, Maeva Monier, Andrew Shepherd, and Andrea K. Steiner
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010504 meteorology & atmospheric sciences ,Effects of global warming on oceans ,Global warming ,Climate change ,010502 geochemistry & geophysics ,Atmospheric sciences ,01 natural sciences ,Earth system science ,Atmosphere ,Solar gain ,Cryosphere ,Environmental science ,Sea level ,0105 earth and related environmental sciences - Abstract
Human-induced atmospheric composition changes cause a radiative imbalance at the top-of-atmosphere which is driving global warming. This Earth Energy Imbalance (EEI) is a fundamental metric of climate change. Understanding the heat gain of the Earth system from this accumulated heat – and particularly how much and where the heat is distributed in the Earth system – is fundamental to understanding how this affects warming oceans, atmosphere and land, rising temperatures and sea level, and loss of grounded and floating ice, which are fundamental concerns for society. This study is a Global Climate Observing System (GCOS) concerted international effort to update the Earth heat inventory, and presents an updated international assessment of ocean warming estimates, and new and updated estimates of heat gain in the atmosphere, cryosphere and land over the period 1960–2018. The study obtains a consistent long-term Earth system heat gain over the past 58 years, with a total heat gain of 393 ± 40 ZJ, which is equivalent to a heating rate of 0.42 ± 0.04 W m−2. The majority of the heat gain (89 %) takes place in the global ocean (0–700 m: 53 %; 700–2000 m: 28 %; > 2000 m: 8 %), while it amounts to 6 % for the land heat gain, to 4 % available for the melting of grounded and floating ice, and to 1 % for atmospheric warming. These new estimates indicate a larger contribution of land and ice heat gain (10 % in total) compared to previous estimates (7 %). There is a regime shift of the Earth heat inventory over the past 2 decades, which appears to be predominantly driven by heat sequestration into the deeper layers of the global ocean, and a doubling of heat gain in the atmosphere. However, a major challenge is to reduce uncertainties in the Earth heat inventory, which can be best achieved through the maintenance of the current global climate observing system, its extension into areas of gaps in the sampling, as well as to establish an international framework for concerted multi-disciplinary research of the Earth heat inventory. Earth heat inventory is published at DKRZ (https://www.dkrz.de/) under the doi: https://doi.org/10.26050/WDCC/GCOS_EHI_EXP (von Schuckmann et al., 2020).
- Published
- 2020
20. Ocean Warming: From the Surface to the Deep in Observations and Models
- Author
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P. J. Gleckler, Paul J. Durack, Sarah G. Purkey, Gregory C. Johnson, Timothy P. Boyer, and John M. Lyman
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Surface (mathematics) ,010504 meteorology & atmospheric sciences ,global climate system ,Effects of global warming on oceans ,010502 geochemistry & geophysics ,Oceanography ,01 natural sciences ,ocean warming ,lcsh:Oceanography ,greenhouse gas ,Environmental science ,lcsh:GC1-1581 ,0105 earth and related environmental sciences - Abstract
The ocean is the primary heat sink of the global climate system. Since 1971, it has been responsible for storing more than 90% ofthe excess heat added to the Earth system by anthropogenic greenhouse-gas emissions. Adding this heat to the ocean contributes substantially to sea level rise and affects vital marine ecosystems. Considering the global ocean’s large role in ongoing climate variability and change, it is a good place to focus in order to understand what observed changes have occurred to date and, by using models, what future changes might arise under continued anthropogenic forcing of the climate system. While sparse measurement coverage leads to enhanced uncertainties with long-term historical estimates of change, modern measurements are beginning to provide the clearest picture yet of ongoing global ocean change. Observations show that the ocean is warming from the near-surface through to the abyss, a conclusion that is strengthened with each new analysis. In this assessment, we revisit observation- and model-based estimates of ocean warming from the industrial era to the present and show a consistent, full-depth pattern of change over the observed record that is likely to continue at an ever-increasing pace if effective actions to reduce greenhouse-gas emissions are not taken.
- Published
- 2018
21. Measuring Global Ocean Heat Content to Estimate the Earth Energy Imbalance
- Author
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Masayoshi Ishii, Tristan L'Ecuyer, Rebecca Cowley, Dean Roemmich, Susan Wijffels, N. V. Zilberman, Steve Piotrowicz, Viktor Gouretski, Detlef Stammer, Donata Giglio, John Abraham, Matthew D. Palmer, Sabrina Speich, Felix W. Landerer, Maria Z. Hakuba, Gongjie Wang, Lijing Cheng, Abhishek Savita, Rémy Roca, John A. Church, John M. Lyman, Seiji Kato, Catia M. Domingues, Karina von Schuckmann, Anny Cazenave, William Llovel, Benoit Meyssignac, Timothy P. Boyer, Alejandro Blazquez, David Legler, Graeme L. Stephens, Sarah G. Purkey, Rachel Killick, Zhongxiang Zhao, Gregory C. Johnson, Armin Köhl, Michael Ablain, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Applied Physics Laboratory [Seattle] (APL-UW), University of Washington [Seattle], Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Center for Earth System Research and Sustainability (CEN), Universität Hamburg (UHH), NASA Langley Research Center [Hampton] (LaRC), Department of Atmospheric and Oceanic Sciences [Madison], University of Wisconsin-Madison, Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales [Toulouse] (CNES)-Météo France-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Institute of Marine Sciences, University of Hamburg, Centre National d'Études Spatiales [Toulouse] (CNES), Climate Change Research Centre [Sydney] (CCRC), University of New South Wales [Sydney] (UNSW), Institute for Marine and Antarctic Studies and Centre for Marine Socioecology, University of Tasmania (UTAS), Cancer Genetics Branch, National Institute of Health (NIH)-National Human Genome Research Institute (NHGRI), National Oceanic and Atmospheric Administration (NOAA), University of California, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
0106 biological sciences ,010504 meteorology & atmospheric sciences ,lcsh:QH1-199.5 ,ocean surface fluxes ,Climate change ,Ocean Engineering ,Aquatic Science ,sea level ,lcsh:General. Including nature conservation, geographical distribution ,Oceanography ,Atmospheric sciences ,01 natural sciences ,Atmosphere ,ARGO ,GRACE ,altimetry ,ocean heat content ,ocean mass ,14. Life underwater ,Altimeter ,lcsh:Science ,Sea level ,Argo ,ComputingMilieux_MISCELLANEOUS ,0105 earth and related environmental sciences ,Water Science and Technology ,Global and Planetary Change ,010604 marine biology & hydrobiology ,Earth Energy Imbalance ,13. Climate action ,Greenhouse gas ,[SDE]Environmental Sciences ,Environmental science ,Satellite ,lcsh:Q ,Ocean heat content - Abstract
The energy radiated by the Earth toward space does not compensate the incoming radiation from the Sun leading to a small positive energy imbalance at the top of the atmosphere (0.4-1 Wm(-2)). This imbalance is coined Earth's Energy Imbalance (EEI). It is mostly caused by anthropogenic greenhouse gas emissions and is driving the current warming of the planet. Precise monitoring of EEI is critical to assess the current status of climate change and the future evolution of climate. But the monitoring of EEI is challenging as EEI is two orders of magnitude smaller than the radiation fluxes in and out of the Earth system. Over 93% of the excess energy that is gained by the Earth in response to the positive EEI accumulates into the ocean in the form of heat. This accumulation of heat can be tracked with the ocean observing system such that today, the monitoring of Ocean Heat Content (OHC) and its long-term change provide the most efficient approach to estimate EEI. In this community paper we review the current four state-of-the-art methods to estimate global OHC changes and evaluate their relevance to derive EEI estimates on different time scales. These four methods make use of: (1) direct observations of in situ temperature; (2) satellite-based measurements of the ocean surface net heat fluxes; (3) satellite-based estimates of the thermal expansion of the ocean and (4) ocean reanalyses that assimilate observations from both satellite and in situ instruments. For each method we review the potential and the uncertainty of the method to estimate global OHC changes. We also analyze gaps in the current capability of each method and identify ways of progress for the future to fulfill the requirements of EEI monitoring. Achieving the observation of EEI with sufficient accuracy will depend on merging the remote sensing techniques with in situ measurements of key variables as an integral part of the Ocean Observing System.
- Published
- 2019
22. Sensitivity of Global Upper-Ocean Heat Content Estimates to Mapping Methods, XBT Bias Corrections, and Baseline Climatologies*
- Author
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J. Antonov, Catia M. Domingues, Masayoshi Ishii, Josh K. Willis, John A. Church, Viktor Gouretski, John M. Lyman, Timothy P. Boyer, Rebecca Cowley, Susan Wijffels, Nathaniel L. Bindoff, Gregory C. Johnson, and Simon A. Good
- Subjects
Atmospheric Science ,010504 meteorology & atmospheric sciences ,010505 oceanography ,Climate change ,01 natural sciences ,Sea level rise ,Climatology ,Environmental science ,Bias correction ,Sensitivity (control systems) ,Ocean heat content ,Bathythermograph ,Baseline (configuration management) ,0105 earth and related environmental sciences - Abstract
Ocean warming accounts for the majority of the earth’s recent energy imbalance. Historic ocean heat content (OHC) changes are important for understanding changing climate. Calculations of OHC anomalies (OHCA) from in situ measurements provide estimates of these changes. Uncertainties in OHCA estimates arise from calculating global fields from temporally and spatially irregular data (mapping method), instrument bias corrections, and the definitions of a baseline climatology from which anomalies are calculated. To investigate sensitivity of OHCA estimates for the upper 700 m to these different factors, the same quality-controlled dataset is used by seven groups and comparisons are made. Two time periods (1970–2008 and 1993–2008) are examined. Uncertainty due to the mapping method is 16.5 ZJ for 1970–2008 and 17.1 ZJ for 1993–2008 (1 ZJ = 1 × 1021 J). Uncertainty due to instrument bias correction varied from 8.0 to 17.9 ZJ for 1970–2008 and from 10.9 to 22.4 ZJ for 1993–2008, depending on mapping method. Uncertainty due to baseline mean varied from 3.5 to 14.5 ZJ for 1970–2008 and from 2.7 to 9.8 ZJ for 1993–2008, depending on mapping method and offsets. On average mapping method is the largest source of uncertainty. The linear trend varied from 1.3 to 5.0 ZJ yr−1 (0.08–0.31 W m−2) for 1970–2008 and from 1.5 to 9.4 ZJ yr−1 (0.09–0.58 W m−2) for 1993–2008, depending on method, instrument bias correction, and baseline mean. Despite these complications, a statistically robust upper-ocean warming was found in all cases for the full time period.
- Published
- 2016
23. Informing Deep Argo Array Design Using Argo and Full-Depth Hydrographic Section Data
- Author
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Sarah G. Purkey, Gregory C. Johnson, and John M. Lyman
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Atmospheric Science ,Section (archaeology) ,Climatology ,Ocean Engineering ,Ocean heat content ,Scale (map) ,Longitude ,Hydrography ,Sea level ,Geology ,Argo ,Latitude - Abstract
Data from full-depth closely sampled hydrographic sections and Argo floats are analyzed to inform the design of a future Deep Argo array. Here standard errors of local decadal temperature trends and global decadal trends of ocean heat content and thermosteric sea level anomalies integrated from 2000 to 6000 dbar are estimated for a hypothetical 5° latitude × 5° longitude × 15-day cycle Deep Argo array. These estimates are made using temperature variances from closely spaced full-depth CTD profiles taken during hydrographic sections. The temperature data along each section are high passed laterally at a 500-km scale, and the resulting variances are averaged in 5° × 5° bins to assess temperature noise levels as a function of pressure and geographic location. A mean global decorrelation time scale of 62 days is estimated using temperature time series at 1800 dbar from Argo floats. The hypothetical Deep Argo array would be capable of resolving, at one standard error, local trends from −1 in the quiescent abyssal North Pacific to about 26 m °C decade−1 below 2000 dbar along 50°S in the energetic Southern Ocean. Larger decadal temperature trends have been reported previously in these regions using repeat hydrographic section data, but those very sparse data required substantial spatial averaging to obtain statistically significant results. Furthermore, the array would provide decadal global ocean heat content trend estimates from 2000 to 6000 dbar with a standard error of ±3 TW, compared to a trend standard error of ±17 TW from a previous analysis of repeat hydrographic data.
- Published
- 2015
24. Anomalous eddy heat and freshwater transport in the Gulf of Alaska
- Author
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John M. Lyman and Gregory C. Johnson
- Subjects
geography ,geography.geographical_feature_category ,Continental shelf ,Temperature salinity diagrams ,Sea-surface height ,Oceanography ,Geophysics ,Eddy ,Space and Planetary Science ,Geochemistry and Petrology ,Anticyclone ,Ocean gyre ,Earth and Planetary Sciences (miscellaneous) ,Ocean heat content ,Geology ,Argo - Abstract
Characteristics of eddies in the Gulf of Alaska are assessed from January 2003 through April 2012. Ensemble statistics for eddy subsurface water properties on isopycnals are computed using temperature and salinity profiles from Argo profiling floats located within eddies, which are identified in sea-surface height using objective techniques. Ninety cyclonic and 154 anticyclonic eddies are identified during this period. The anticyclonic eddies are strongly nonlinear and exhibit significant warm subsurface temperature anomalies and associated salty anomalies on isopycnals while no clear distinguishing subsurface anomalies on isopycnals are detected in association with the cyclonic eddies. Heat and freshwater fluxes for the eddies are estimated from integrations in depth coordinates. The anticyclonic eddies transport heat both westward off the continental shelf into the Subarctic Gyre and westward within the Alaskan Stream. However, they transport salt into the Subarctic Gyre and freshwater within the Alaskan Stream. In both pathways eddy heat and freshwater transport show possible year-to-year fluctuations, varying from 0 to 50.4 × 1018 J a−1 and −16.8 to +7.4 km3 a−1, respectively. The anticyclonic eddies are capped by relatively fresh water year-round.
- Published
- 2015
25. Estimating Global Ocean Heat Content Changes in the Upper 1800 m since 1950 and the Influence of Climatology Choice*
- Author
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Gregory C. Johnson and John M. Lyman
- Subjects
Atmospheric Science ,Sea surface temperature ,Climatology ,Climate change ,Ocean heat content ,Bathythermograph ,Geology ,Argo - Abstract
Ocean heat content anomalies are analyzed from 1950 to 2011 in five distinct depth layers (0–100, 100–300, 300–700, 700–900, and 900–1800 m). These layers correspond to historic increases in common maximum sampling depths of ocean temperature measurements with time, as different instruments—mechanical bathythermograph (MBT), shallow expendable bathythermograph (XBT), deep XBT, early sometimes shallower Argo profiling floats, and recent Argo floats capable of worldwide sampling to 2000 m—have come into widespread use. This vertical separation of maps allows computation of annual ocean heat content anomalies and their sampling uncertainties back to 1950 while taking account of in situ sampling advances and changing sampling patterns. The 0–100-m layer is measured over 50% of the globe annually starting in 1956, the 100–300-m layer starting in 1967, the 300–700-m layer starting in 1983, and the deepest two layers considered here starting in 2003 and 2004, during the implementation of Argo. Furthermore, global ocean heat uptake estimates since 1950 depend strongly on assumptions made concerning changes in undersampled or unsampled ocean regions. If unsampled areas are assumed to have zero anomalies and are included in the global integrals, the choice of climatological reference from which anomalies are estimated can strongly influence the global integral values and their trend: the sparser the sampling and the bigger the mean difference between climatological and actual values, the larger the influence.
- Published
- 2014
26. The Coherence and Impact of Meridional Heat Transport Anomalies in the Atlantic Ocean Inferred from Observations*
- Author
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Kathryn A. Kelly, LuAnne Thompson, and John M. Lyman
- Subjects
Atmospheric Science ,Temporal resolution ,Climatology ,Ocean current ,Thermohaline circulation ,Zonal and meridional ,Sea-surface height ,Antarctic oscillation ,Hydrography ,Geology ,Sea level - Abstract
Observations of thermosteric sea level (TSL) from hydrographic data, equivalent water thickness (EWT) from the Gravity Recovery and Climate Experiment (GRACE), and altimetric sea surface height (SSH) are used to infer meridional heat transport (MHT) anomalies for the Atlantic Ocean. An “unknown control” version of a Kalman filter in each of eight regions extracts smooth estimates of heat transport convergence (HTC) from discrepancies between the response to monthly surface heat and freshwater fluxes and observed mass and heat content. Two models are used: model A using only the heat budget for 1993–2010 and model B using both heat and mass budgets for 2003–10. Based on the small contributions of mass to SSH, model A is rerun using SSH in place of TSL to improve temporal resolution and data consistency. Estimates of MHT are derived by summing the HTC from north to south assuming either negligible anomalies at 67°N or setting MHT to observed values near 40°N. Both methods show that MHT is highly coherent between 35°S and 40°N. The former method gives a large drop in coherence north of 40°N while the latter method gives a less dramatic drop. Estimated anomalies in MHT comparable to or larger than that recently observed at the Rapid Climate Change and Meridional Overturning Circulation and Heatflux Array (RAPID/MOCHA) line at 26.5°N have occurred multiple times in this 18-yr period. Positive anomalies in coherent MHT correspond to increased heat loss in the North Atlantic subtropical gyre demonstrating the feedback of oceanic heat transport anomalies on air–sea fluxes. A correlation of MHT with the Antarctic Oscillation suggests a southern source for the coherent MHT anomalies.
- Published
- 2014
27. Observed changes in top-of-the-atmosphere radiation and upper-ocean heating consistent within uncertainty
- Author
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Takmeng Wong, Gregory C. Johnson, Graeme L. Stephens, David R. Doelling, Richard P. Allan, Brian J. Soden, Norman G. Loeb, and John M. Lyman
- Subjects
Sunlight ,Atmosphere ,Earth's energy budget ,Thermal radiation ,Climatology ,Global warming ,General Earth and Planetary Sciences ,Environmental science ,Climate science ,Radiation ,Ocean heat content ,Atmospheric sciences - Abstract
Global climate change results from a small yet persistent imbalance between the amount of sunlight absorbed by the Earth and the thermal radiation emitted back to space. A revised analysis of measured changes in the net radiation imbalance at the top of the atmosphere, and the ocean heat content to a depth of 1,800 m, suggests that these two sets of observations are consistent within error margins.
- Published
- 2012
28. Estimating Global Energy Flow from the Global Upper Ocean
- Author
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John M. Lyman
- Subjects
Atmosphere ,Global energy ,Geophysics ,Geochemistry and Petrology ,Climatology ,Anomaly (natural sciences) ,Flow (psychology) ,Environmental science ,Satellite ,Ocean heat content ,Confidence interval ,Relative significance - Abstract
The relative significance of short multi-year linear trends in the global integral of 0–700 m ocean heat content anomaly (OHCA) is investigated by examining the overlapping segments of the 16-year OHCA curve from Lyman et al. (Nature 465:334–337, 2010). Segments of 4 years and less are found not to be significantly different from each other or from 0 at the 90% confidence interval. Likewise, short 5- to 7-year segments are not statistically different from each other. Ten-year and longer trends are significant and provide a useful comparison for satellite observations of the radiation imbalance at the top of the atmosphere.
- Published
- 2011
29. A computational method for determining XBT depths
- Author
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John M Gorman, John R. Stark, John Abraham, Joshua K. Willis, Mireno Borghini, Michael P. Hennessey, John M. Lyman, and Franco Reseghetti
- Subjects
lcsh:GE1-350 ,Drag coefficient ,Computer simulation ,Flow (psychology) ,lcsh:Geography. Anthropology. Recreation ,Mechanics ,Physics::Fluid Dynamics ,Flow separation ,Classical mechanics ,lcsh:G ,Drag ,Fluid dynamics ,Bathythermograph ,lcsh:Environmental sciences ,Mathematics ,Communication channel - Abstract
A new technique for determining the depth of expendable bathythermographs (XBTs) is developed. This new method uses a forward-stepping calculation which incorporates all of the forces on the XBT devices during their descent. Of particular note are drag forces which are calculated using a new drag coefficient expression. That expression, obtained entirely from computational fluid dynamic modeling, accounts for local variations in the ocean environment. Consequently, the method allows for accurate determination of depths for any local temperature environment. The results, which are entirely based on numerical simulation, are compared with the experiments of LM Sippican T-5 XBT probes. It is found that the calculated depths differ by less than 3% from depth estimates using the standard fall-rate equation (FRE). Furthermore, the differences decrease with depth. The computational model allows an investigation of the fluid flow patterns along the outer surface of the probe as well as in the interior channel. The simulations take account of complex flow phenomena such as laminar-turbulent transition and flow separation.
- Published
- 2011
30. In Situ Data Biases and Recent Ocean Heat Content Variability*
- Author
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Josh K. Willis, Gregory C. Johnson, John M. Lyman, and John Gilson
- Subjects
In situ ,Atmospheric Science ,Climatology ,Environmental science ,Climate change ,Ocean Engineering ,Sampling error ,Sources of error ,Ocean heat content ,Bathythermograph ,Argo - Abstract
Two significant instrument biases have been identified in the in situ profile data used to estimate globally integrated upper-ocean heat content. A large cold bias was discovered in a small fraction of Argo floats along with a smaller but more prevalent warm bias in expendable bathythermograph (XBT) data. These biases appear to have caused the bulk of the upper-ocean cooling signal reported by Lyman et al. between 2003 and 2005. These systematic data errors are significantly larger than sampling errors in recent years and are the dominant sources of error in recent estimates of globally integrated upper-ocean heat content variability. The bias in the XBT data is found to be consistent with errors in the fall-rate equations, suggesting a physical explanation for that bias. With biased profiles discarded, no significant warming or cooling is observed in upper-ocean heat content between 2003 and 2006.
- Published
- 2009
31. Estimating Annual Global Upper-Ocean Heat Content Anomalies despite Irregular In Situ Ocean Sampling*
- Author
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John M. Lyman and Gregory C. Johnson
- Subjects
In situ ,Atmospheric Science ,Meteorology ,Sampling distribution ,Climatology ,Environmental science ,Sea-surface height ,Ocean heat content ,Confidence interval ,Argo ,Proxy (climate) ,Ocean sampling - Abstract
The effects of irregular in situ ocean sampling on estimates of annual globally integrated upper ocean heat content anomalies (OHCA) are investigated for sampling patterns from 1955 to 2006. An analytical method is presented for computing the effective area covered by an objective map for any given in situ sampling distribution. To evaluate the method, appropriately scaled sea surface height (SSH) anomaly maps from Archiving, Validation, and Interpretation of Satellite Oceanographic data (AVISO) are used as a proxy for OHCA from 1993 to 2006. Use of these proxy data demonstrates that the simple area integral (SI) of such an objective map for sparse datasets does not agree as well with the actual integral as the weighted integral (WI), defined as the simple integral weighted by the ratio of the total area over the “observed” area. From 1955 to 1966, in situ ocean sampling is inadequate to estimate accurately annual global integrals of the proxy upper OHCA. During this period, the SI for the sampling pattern of any given year underestimates the 13-yr trend in proxy OHCA from 1993 to 2006 by around 70%, and confidence limits for the WI are often very large. From 1967 to 2003 there appear to be sufficient data to estimate annual global integrals. Limited by the constraints of this analysis, the SI for any given year’s sampling pattern still underestimates the 1993–2006 13-yr trend in the proxy by around 30%, but the WI matches the trend well with small confidence limits. For 2004 through 2006 in situ sampling, with near-global in situ Argo data coverage, the 1993–2006 13-yr trend in the proxy is equally well represented by the SI or WI.
- Published
- 2008
32. Tropical Instability Waves as a Resonance between Equatorial Rossby Waves*
- Author
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John M. Lyman, Roland A. deSzoeke, Dudley B. Chelton, and Roger M. Samelson
- Subjects
Physics ,State variable ,Baroclinity ,Climatology ,Temporal resolution ,Tropical instability waves ,Wind wave ,Rossby wave ,Resonance ,Geophysics ,Sea-surface height ,Oceanography ,Physics::Atmospheric and Oceanic Physics - Abstract
To understand the characteristics of sea surface height signatures of tropical instability waves (TIWs), a linearized model of the central Pacific Ocean was developed in which the vertical structures of the state variables are projected onto a set of orthogonal baroclinic eigenvectors. In lieu of in situ current measurements with adequate spatial and temporal resolution, the mean current structure used in the model was obtained from the Parallel Ocean Climate Model (POCM). The TIWs in the linear model have cross-equatorial structure and wavenumber–frequency content similar to the TIWs in POCM, even when the vertical structures of the state variables are projected onto only the first two orthogonal baroclinic eigenvectors. Because this model is able to reproduce TIWs with relatively simple vertical structure, it is possible to examine the mechanism for the formation of TIWs. TIWs are shown to form from a resonance between two equatorial Rossby waves as the strength of the background currents is slowly increased.
- Published
- 2005
33. Improving estimates of Earth's energy imbalance
- Author
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Gregory C. Johnson, Norman G. Loeb, and John M. Lyman
- Subjects
010504 meteorology & atmospheric sciences ,Meteorology ,0211 other engineering and technologies ,Climate change ,02 engineering and technology ,Environmental Science (miscellaneous) ,Physical oceanography ,Atmospheric sciences ,01 natural sciences ,Environmental science ,Earth (chemistry) ,Social Sciences (miscellaneous) ,Energy (signal processing) ,021101 geological & geomatics engineering ,0105 earth and related environmental sciences - Published
- 2016
34. State of the Climate in 2013
- Author
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Olga Clorinda Penalba, David A. Robinson, Steve Ready, Edward Hanna, Philip J. Klotzbach, Christopher W. Landsea, Hugo G. Hidalgo, Ursula Schauer, H. Loeng, Martin O. Jeffries, Jacqueline M. Spence, Christopher S. Meinen, Garret G. Campbell, Qiuhong Tang, Muyin Wang, Hongxing Liu, R. Yamada, Gloria L. Manney, Nicolas Fauchereau, Xavier Fettweis, Ricardo M. Trigo, S Barreira, Norman G. Loeb, Tuomas Laurila, Uwe Send, Eduardo Zambrano, Alexander Baklanov, Diego Loyola, Eleanor Frajka-Williams, Ahira Sánchez-Lugo, Kaarle Kupiainen, Gabriel J. Wolken, H. Kheyrollah Pour, John Kennedy, Simon McGree, Nicolai I. Shiklomanov, Alberto Setzer, Vernie Marcellin-Honore’, Adelina Albanil, Jack Kohler, Patricia K. Quinn, Edward J. Dlugokencky, N. G. Oberman, L. Chang’a, Laurence C. Smith, David Burgess, Peter Schlosser, Jochem Marotzke, Eric S. Blake, Shujie Wang, Arne Dahlback, Shotaro Tanaka, Vladimir E. Romanovsky, David A. Siegel, Agnes Kijazi, P. Sawaengphokhai, Lori Bruhwiler, Jeremy T. Mathis, Jason E. Box, R. B. Ingvaldsen, Stacey M. Frith, Stanley B. Goldenberg, Michele L. Newlin, Igor V. Polyakov, Kyun Kuk Kang, Robert Whitewood, Suzana J. Camargo, John A. Augustine, Natalya Kramarova, James W. Elkins, Michael S. Halpert, Zeng-Zhen Hu, M. C. Gregg, James S. Famiglietti, Johannes W. Kaiser, Mary-Louise Timmermans, William E. Johns, Melanie Coldewey-Egbers, Chris K. Folland, Shaun Quegan, Kazuyoshi Yoshimatsu, Marcel Nicolaus, Michael Kendon, Steven A. Ackerman, Gerard McCarthy, Peter Ambenje, Ivan E. Frolov, Laban Ogallo, Juan Bazo, Jonathan Gottschalck, Kaisa Lakkala, Alexandre M. Ramos, Arun Kumar, Serhat Sensoy, Russell S. Vose, Matthias Lankhorst, Isabelle Tobin, Allen Pope, Hyuanjun Kim, Nadine Gobron, R. Pascual, Samuel Remy, Chris Fenimore, Wassila M. Thiaw, Sharon L. Smith, Samar Khatiwala, Linda M. Keller, Jnes Uwe Grooß, Shashi K. Gupta, Fatemeh Rahimzadeh, Benjamin Rabe, Jacqueline A. Richter-Menge, Mauri Pelto, K. S. Law, Lisan Yu, Catia M. Domingues, Kathleen Dohan, Jake Crouch, Taro Takahashi, Robert Vautard, Germar Bernhard, Don P. Chambers, P. Luhunga, Song Shu, T. S. Jensen, Ryan L. Fogt, Silvia L. Garzoli, T. Kikuchi, Robert Dunn, José Luis Stella, H. Ng’ongolo, Joshua K. Willis, Andreas Herber, Gualberto Carrasco, Geoff S. Dutton, Yan Xue, Kyle Hilburn, Laura C. Brown, Gustavo J. Goni, Paul A. Newman, Ricardo A. Locarnini, E. Hyung Park, Mario Bidegain, Chris T. Fogarty, Jorge A. Amador, Hiroshi Ohno, David E. Parker, I. Hanssen-Bauer, Johannes Flemming, J. V. Revadekar, Michael C. Pitts, Alexandre Bernardes Pezza, Chunzai Wang, Bryan A. Franz, Jared Rennie, Scott J. Weaver, Thomas M. Smith, Stuart A. Cunningham, K. von Salzen, Shigeto Nishino, Stephen Baxter, Rene Lobato, David P. Kratz, I. A. James, Zo Rakotomavo, Peter Thorne, Kathleen L. McInnes, Phillipe Ciais, Von P. Walden, Martin Stengel, Geir O. Braathen, J. L. Vazquez, Angela Benedetti, Daniel Chung, Todd B. Kimberlain, Lincoln M. Alves, Christopher J. Cox, Mark Flanner, Jae Schemm, Peiqun Zhang, Eric J. Alfaro, Dmitry A. Streletskiy, John Cappelen, Yinghui Liu, Terry Haran, Natalia N. Korshunova, Jessica N. Cross, Idelmis T. Gonzalez, Uma S. Bhatt, Tannecia S. Stephenson, Nick Rayner, Shenfu Dong, Takmeng Wong, Xungang Yin, Ingrid L. Rivera, Seong-Joong Kim, David A. Smeed, Peter Bissolli, Mary Butler, Maurizio Santoro, Jerry Ziemke, Will Hobbs, Jeffrey R. Key, P. Jeremy Werdell, Bryan J. Johnson, Wiley Evans, Lamjav Oyunjargal, Liang Peng, Arlene P. Aaron-Morrison, John J. Marra, Avalon O. Porter, Juan Arévalo, Andries Kruger, Blanca Calderón, Phillip Reid, James A. Renwick, Stefan Hendricks, Christoph Reimer, Gregory C. Johnson, Gary T. Mitchum, Torsten Kanzow, John Wahr, K. Alama Coulibaly, G. V. Malkova, David H. Bromwich, Michael A. Taylor, Shu Oeng Ben Ho, Christian Euscátegui, Rick Lumpkin, Matthew A. Lazzara, Michael J. Behrenfeld, Kyle R. Clem, Ross Brown, Michael J. Foster, Juan José Nieto, Robert A. Massom, Blair Trewin, John I. Antonov, Mark A. Merrifield, Christoph Paulik, Guido R. van der Werf, Robert Parinussa, Mark A. Lander, Mark Weber, Diana Hovhannisyan, Rochard A.M. de Jeu, Jennifer A. Francis, L. M. Andreassen, Anthony Arendt, Rik Wanninkhof, Sebastian Hahn, Walter N. Meier, Gustavo Goni, Vyacheslav N. Razuvaev, Robert S. Pickart, John R. Christy, Xiangze Jin, José A. Marengo, Awatif Ebrahim, Eric R. Nash, Rolf Müller, Donald K. Perovich, Chris Derksen, H. K. Ha, Ben Hamlington, L. Jones, Junhong Wang, Guillaume Jumaux, Denis Volkov, I-I Lin, Christopher S. Oludhe, Asa K. Rennermalm, Caio A. S. Coelho, Stephen A. Montzka, Vladimir Sokolov, Rebecca A. Woodgate, Paul Berrisford, Ted Scambos, John Walsh, Michiyo Yamamoto-Kawai, Andrew K. Heidinger, Tim R. McVicar, Shih-Yu Wang, Amal Sayouri, S. J. Vavrus, Jing-Jia Luo, Philip R. Thompson, Katja Trachte, James Reagan, Olga N. Bulygina, Wolfgang Wagner, Mark Tschudi, Derek S. Arndt, Zachary Atheru, Sangeeta Sharma, Christopher L. Sabine, John M. Lyman, David Phillips, Carl Mears, Richard A. Krishfield, Ana María Durán-Quesada, Darren Rayner, Molly O. Baringer, Fatou Sima, Jhan Carlo Espinoza, Taikan Oki, James E. Overland, Sharon Stammerjohn, Hsun Ying Kao, Gerald D. Bell, Bjørn Helge Johnsen, Bin Wang, Thomas E. Evans, William J. Williams, Jan L. Lieser, John A. Knaff, B. M. Kim, Tapani Koskela, Antje Inness, Andre Obregon, Alexander Kholodov, Carla Vega, Andreas Becker, B. C. Maddux, Andrew Lorrey, Khadija Kabidi, Pamela Levira, Helga Nitsche, M. L. Geai, Igor Ashik, S. Zimmerman, Charles Chip Guard, J A Ronald van der, Lin Zhao, Petra R. Chappell, Timothy P. Boyer, Dmitry Drozdov, Bert Wouters, Jayaka D. Campbell, Francis S. Dekaa, W. M. Smethie, Viva Banzon, R. Steven Nerem, Rob Allan, Craig S. Long, R. Martinez, Sergei Marchenko, Wolfgang Steinbrecht, Karin Gleason, Robert S. Stone, Lei Wang, A. Brett Mullan, Skie Tobin, Jeannette Noetzli, Doug Worthy, Vigdis Vestreng, Michelle L. Santee, Kate M. Willett, Nathan Bindoff, Michael Steele, Karen H. Rosenlof, Anu Heikkilä, Claude R. Duguay, Josyane Ronchail, Anne C. Wilber, A. Johannes Dolman, A. K. Srivastava, Andreas Stohl, M. Rajeevan, R. S. W. van de Wal, Catherine Ganter, Markus G. Donat, Adrian R. Trotman, Lucie A. Vincent, Carl J. Schreck, Richard A. Feely, Y. Y. Liu, Michelle L’Heureux, Kari Luojus, Mauro Gugliemin, Charlotte McBride, Howard J. Diamond, David Barriopedro, Rosalind C. Blenman, Tove Marit Svendby, Jessica Blunden, Sebastian Gerland, Paul W. Stackhouse, Simon A. Good, Guojie Wang, Richard J. Pasch, Julia Schmale, Glenroy Brown, B. D. Hall, Sean M. Davis, Mahbobeh Khoshkam, John M. Toole, Claudia Schmid, Bernard Pinty, Wilson Gitau, Leif G. Anderson, Matthew Rodell, Kathy Lantz, Dale F. Hurst, Hanne H. Christiansen, Thomas L. Mote, Owen R. Cooper, Richard R. Heim, William Sweet, Eric Leuliette, G. S.E. Lagerloef, Gregor Macara, Marco Tedesco, Vitali Fioletov, T. W. Kim, Melisa Menendez, Natalie McLean, J. D. Wild, Steve Colwell, Michael C. Kruk, Martin Sharp, J.-J. Morcrette, Jens Mühle, and Wouter Dorigo
- Subjects
Atmospheric Science ,010504 meteorology & atmospheric sciences ,Meteorology ,Download ,010502 geochemistry & geophysics ,01 natural sciences ,Geography ,13. Climate action ,Synoptic scale meteorology ,F860 Climatology ,Data_FILES ,14. Life underwater ,State (computer science) ,0105 earth and related environmental sciences - Abstract
In 2013, the vast majority of the monitored climate variables reported here maintained trends established in recent decades. ENSO was in a neutral state during the entire year, remaining mostly on the cool side of neutral with modest impacts on regional weather patterns around the world. This follows several years dominated by the effects of either La Niña or El Niño events. According to several independent analyses, 2013 was again among the 10 warmest years on record at the global scale, both at the Earths surface and through the troposphere. Some regions in the Southern Hemisphere had record or near-record high temperatures for the year. Australia observed its hottest year on record, while Argentina and New Zealand reported their second and third hottest years, respectively. In Antarctica, Amundsen-Scott South Pole Station reported its highest annual temperature since records began in 1957. At the opposite pole, the Arctic observed its seventh warmest year since records began in the early 20th century. At 20-m depth, record high temperatures were measured at some permafrost stations on the North Slope of Alaska and in the Brooks Range. In the Northern Hemisphere extratropics, anomalous meridional atmospheric circulation occurred throughout much of the year, leading to marked regional extremes of both temperature and precipitation. Cold temperature anomalies during winter across Eurasia were followed by warm spring temperature anomalies, which were linked to a new record low Eurasian snow cover extent in May. Minimum sea ice extent in the Arctic was the sixth lowest since satellite observations began in 1979. Including 2013, all seven lowest extents on record have occurred in the past seven years. Antarctica, on the other hand, had above-average sea ice extent throughout 2013, with 116 days of new daily high extent records, including a new daily maximum sea ice area of 19.57 million km2 reached on 1 October. ENSO-neutral conditions in the eastern central Pacific Ocean and a negative Pacific decadal oscillation pattern in the North Pacific had the largest impacts on the global sea surface temperature in 2013. The North Pacific reached a historic high temperature in 2013 and on balance the globally-averaged sea surface temperature was among the 10 highest on record. Overall, the salt content in nearsurface ocean waters increased while in intermediate waters it decreased. Global mean sea level continued to rise during 2013, on pace with a trend of 3.2 mm yr-1 over the past two decades. A portion of this trend (0.5 mm yr-1) has been attributed to natural variability associated with the Pacific decadal oscillation as well as to ongoing contributions from the melting of glaciers and ice sheets and ocean warming. Global tropical cyclone frequency during 2013 was slightly above average with a total of 94 storms, although the North Atlantic Basin had its quietest hurricane season since 1994. In the Western North Pacific Basin, Super Typhoon Haiyan, the deadliest tropical cyclone of 2013, had 1-minute sustained winds estimated to be 170 kt (87.5 m s-1) on 7 November, the highest wind speed ever assigned to a tropical cyclone. High storm surge was also associated with Haiyan as it made landfall over the central Philippines, an area where sea level is currently at historic highs, increasing by 200 mm since 1970. In the atmosphere, carbon dioxide, methane, and nitrous oxide all continued to increase in 2013. As in previous years, each of these major greenhouse gases once again reached historic high concentrations. In the Arctic, carbon dioxide and methane increased at the same rate as the global increase. These increases are likely due to export from lower latitudes rather than a consequence of increases in Arctic sources, such as thawing permafrost. At Mauna Loa, Hawaii, for the first time since measurements began in 1958, the daily average mixing ratio of carbon dioxide exceeded 400 ppm on 9 May. The state of these variables, along with dozens of others, and the 2013 climate conditions of regions around the world are discussed in further detail in this 24th edition of the State of the Climate series. © 2014, American Meteorological Society. All rights reserved.
- Published
- 2014
35. A review of global ocean temperature observations: Implications for ocean heat content estimates and climate change
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Isabella Velicogna, Alison M. Macdonald, Lijing Cheng, John Abraham, Matthew D. Palmer, Molly O. Baringer, John M Gorman, Timothy P. Boyer, Karina von Schuckmann, Shoichi Kizu, Jessica L. Conroy, Joshua K. Willis, John M. Lyman, Gustavo Goni, Nathaniel L. Bindoff, Viktor Gouretski, Masayoshi Ishii, Gregory C. Johnson, John A. Church, Simon A. Good, Catia M. Domingues, John T. Fasullo, Alberto R. Piola, S. E. Moffitt, Kevin E. Trenberth, Franco Reseghetti, John Gilson, W. J. Minkowycz, and Reseghetti, F.
- Subjects
010504 meteorology & atmospheric sciences ,Climate change ,Argo float ,global warming ,010502 geochemistry & geophysics ,01 natural sciences ,Deep sea ,expendable bathythermograph ,western South-Atlantic ,ocean heat content ,Physical Sciences and Mathematics ,thermosteric sea level rise ,14. Life underwater ,theta-s climatology ,Argo ,Sea level ,0105 earth and related environmental sciences ,surface temperatures ,Global warming ,content variability ,sea-level rise ,expendable bathythermograph XBT ,fall-rate ,Sea surface temperature ,Geophysics ,subsurface temperature ,13. Climate action ,profiling floats ,Earth energy balance ,Climatology ,earths energy imbalance ,Environmental science ,Tide gauge ,Ocean heat content - Abstract
The evolution of ocean temperature measurement systems is presented with a focus on the development and accuracy of two critical devices in use today (expendable bathythermographs and conductivity-temperature-depth instruments used on Argo floats). A detailed discussion of the accuracy of these devices and a projection of the future of ocean temperature measurements are provided. The accuracy of ocean temperature measurements is discussed in detail in the context of ocean heat content, Earth's energy imbalance, and thermosteric sea level rise. Up-to-date estimates are provided for these three important quantities. The total energy imbalance at the top of atmosphere is best assessed by taking an inventory of changes in energy storage. The main storage is in the ocean, the latest values of which are presented. Furthermore, despite differences in measurement methods and analysis techniques, multiple studies show that there has been a multidecadal increase in the heat content of both the upper and deep ocean regions, which reflects the impact of anthropogenic warming. With respect to sea level rise, mutually reinforcing information from tide gauges and radar altimetry shows that presently, sea level is rising at approximately 3 mm yr-1 with contributions from both thermal expansion and mass accumulation from ice melt. The latest data for thermal expansion sea level rise are included here and analyzed. Key Points Oceanographic techniques and analysis have improved over many decadesThese improvements allow more accurate Earth-energy balance estimatesUnderstanding of ocean heat content and sea-level rise has also increased ©2013. American Geophysical Union. All Rights Reserved.
- Published
- 2013
- Full Text
- View/download PDF
36. MIMOC: A global monthly isopycnal upper-ocean climatology with mixed layers
- Author
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Gregory C. Johnson, John M. Lyman, and Sunke Schmidtko
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Water mass ,010504 meteorology & atmospheric sciences ,Mixed layer ,Oceanography ,01 natural sciences ,salinity ,Geochemistry and Petrology ,objective mapping ,Earth and Planetary Sciences (miscellaneous) ,Potential temperature ,14. Life underwater ,mapping ,Argo ,0105 earth and related environmental sciences ,Isopycnal ,010505 oceanography ,temperature ,climatology ,global ,Salinity ,Geophysics ,13. Climate action ,Space and Planetary Science ,Climatology ,Level of detail ,Smoothing ,Geology - Abstract
A monthly, isopycnal/mixed-layer ocean climatology (MIMOC), global from 0 to 1950dbar, is compared with other monthly ocean climatologies. All available quality-controlled profiles of temperature (T) and salinity (S) versus pressure (P) collected by conductivity-temperature-depth (CTD) instruments from the Argo Program, Ice-Tethered Profilers, and archived in the World Ocean Database are used. MIMOC provides maps of mixed layer properties (conservative temperature, , absolute salinity, SA, and maximum P) as well as maps of interior ocean properties (, SA, and P) to 1950dbar on isopycnal surfaces. A third product merges the two onto a pressure grid spanning the upper 1950dbar, adding more familiar potential temperature () and practical salinity (S) maps. All maps are at monthly 0.5 degrees x0.5 degrees resolution, spanning from 80 degrees S to 90 degrees N. Objective mapping routines used and described here incorporate an isobath-following component using a Fast Marching algorithm, as well as front-sharpening components in both the mixed layer and on interior isopycnals. Recent data are emphasized in the mapping. The goal is to compute a climatology that looks as much as possible like synoptic surveys sampled circa 2007-2011 during all phases of the seasonal cycle, minimizing transient eddy and wave signatures. MIMOC preserves a surface mixed layer, minimizes both diapycnal and isopycnal smoothing of -S, as well as preserves density structure in the vertical (pycnoclines and pycnostads) and the horizontal (fronts and their associated currents). It is statically stable and resolves water mass features, fronts, and currents with a high level of detail and fidelity.
- Published
- 2013
37. Relative contributions of temperature and salinity to seasonal mixed layer density changes and horizontal density gradients
- Author
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Sunke Schmidtko, Gregory C. Johnson, and John M. Lyman
- Subjects
Atmospheric Science ,010504 meteorology & atmospheric sciences ,Density gradient ,Mixed layer ,Temperature salinity diagrams ,Soil Science ,Stratification (water) ,Aquatic Science ,Oceanography ,01 natural sciences ,Physics::Geophysics ,Geochemistry and Petrology ,Earth and Planetary Sciences (miscellaneous) ,Southern Hemisphere ,Physics::Atmospheric and Oceanic Physics ,Argo ,0105 earth and related environmental sciences ,Earth-Surface Processes ,Water Science and Technology ,Ecology ,010505 oceanography ,Intertropical Convergence Zone ,Paleontology ,Forestry ,Salinity ,Geophysics ,Space and Planetary Science ,Climatology ,Environmental science - Abstract
Temperature and salinity both contribute to ocean density, including its seasonal cycle and spatial patterns in the mixed layer. Temperature and salinity profiles from the Argo Program allow construction and analysis of a global, monthly, mixed layer climatology. Temperature changes dominate the seasonal cycle of mixed layer density in most regions, but salinity changes are dominant in the tropical warm pools, Arctic, and Antarctic. Under the Intertropical Convergence Zone, temperature and salinity work in concert to increase seasonal stratification, but the seasonal density changes there are weak because the temperature and salinity changes are small. In the eastern subtropics, seasonal salinity changes partly compensate those in temperature and reduce seasonal mixed layer density changes. Besides a hemispheric seasonal reversal, the times of maximum and minimum mixed layer density exhibit regional variations. For instance, the equatorial region is more closely aligned with Southern Hemisphere timing, and much of the North Indian Ocean has a minimum density in May and June. Outside of the tropics, the maximum mixed layer density occurs later in the winter toward the poles, and the minimum earlier in the summer. Finally, at the times of maximum mixed layer density, some of the ocean has horizontal temperature and salinity gradients that work against each other to reduce the horizontal density gradient. However, on the equatorial sides of the subtropical salinity maxima, temperature and salinity gradients reinforce each other, increasing the density gradients there. Density gradients are generally stronger where either salinity or temperature gradients are dominant influences.
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- 2012
38. Where's the heat?
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Gregory C. Johnson and John M. Lyman
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Oceanography ,Meteorology ,Climatology ,Effects of global warming on oceans ,Environmental science ,Satellite ,Environmental Science (miscellaneous) ,Ocean heat content ,Physics::Atmospheric and Oceanic Physics ,Social Sciences (miscellaneous) ,Physics::Geophysics - Abstract
In recent decades, over nine-tenths of Earth's top-of-the-atmosphere energy imbalance has been stored in the ocean, which is rising as it warms. Combining satellite sea-level data with ocean mass data or model results allows insights into ocean warming.
- Published
- 2014
39. Future Observations for Monitoring Global Ocean Heat Content
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Sea Wijffels, Gouretski, Keith Haines, Catia M. Domingues, Timothy P. Boyer, Paul M. Barker, Andrew J. S. Meijers, K von Schuckmann, DE Harrison, Sarah T. Gille, D Smith, Nathaniel L. Bindoff, Lozier, Guinehut, Masayoshi Ishii, Josh K. Willis, J. Antonov, Gregory C. Johnson, Simon A. Good, Peter J. Gleckler, John M. Lyman, M Carson, Palmer, and Sydney Levitus
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Geography ,Meteorology ,Effects of global warming on oceans ,Climatology ,Climate change ,Ocean heat content - Abstract
This community white paper outlines the requirements of the future observing system necessary for measuring and advancing understanding of global ocean heat uptake and heat content variability, with an emphasis on the in situ observing system. We review the progress made in observation-based estimates of ocean heat uptake since Ocean Obs '99 and propose a future observational strategy. Some of the key scientific questions addressed are: 1. What future observations are required to monitor global ocean heat content? 2. How has new technology improved our ability to make estimates of ocean heat uptake? 3. What are the current estimates of global and regional ocean heat uptake and what are the uncertainties? 4. What is the impact of instrumental biases and gridding methodology on estimates of ocean heat uptake?
- Published
- 2010
40. Robust warming of the global upper ocean
- Author
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John M. Lyman, Masayoshi Ishii, Gregory C. Johnson, Josh K. Willis, Viktor Gouretski, Simon A. Good, Doug Smith, and Matthew D. Palmer
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Earth's energy budget ,Multidisciplinary ,Meteorology ,Greenhouse gas ,Effects of global warming on oceans ,Climate change ,Environmental science ,Climate model ,Ocean heat content ,Atmospheric sciences ,Bathythermograph ,Argo - Abstract
The upper ocean acts as a giant heat sink and has absorbed the majority of excess energy generated by anthropogenic greenhouse gasses. This makes ocean heat content, potentially, a key indicator of climate change. But to be useful for evaluating the global energy balance and as a constraint on climate models, the measurement uncertainties of such a key indicator need to be well understood. At present the magnitude of the oceanic heat uptake is highly uncertain, with patterns of inter-annual variability in particular differing among estimates. In a major international collaboration, Lyman et al. compare the available upper-ocean heat content anomaly curves and examine the sources of uncertainly attached to them — including the difficulties in correcting bias in expendable bathythermograph data. They find that, uncertainties notwithstanding, there is clear and robust evidence for a warming trend of 0.64 watts per square metre between 1993 and 2008. The upper 300 m of the world's oceans act as a giant heat sink and have absorbed the majority of the excess energy generated by anthropogenic greenhouse gases. But the magnitude of the oceanic heat uptake is uncertain, and differing estimates have led to questions regarding the closure of the global energy budget. Here, a comparison of ocean heat content estimates is presented; the conclusion is that a robust warming of 0.64 W m−2 occurred from 1993 to 2008. A large (∼1023 J) multi-decadal globally averaged warming signal in the upper 300 m of the world’s oceans was reported roughly a decade ago1 and is attributed to warming associated with anthropogenic greenhouse gases2,3. The majority of the Earth’s total energy uptake during recent decades has occurred in the upper ocean3, but the underlying uncertainties in ocean warming are unclear, limiting our ability to assess closure of sea-level budgets4,5,6,7, the global radiation imbalance8 and climate models5. For example, several teams have recently produced different multi-year estimates of the annually averaged global integral of upper-ocean heat content anomalies (hereafter OHCA curves) or, equivalently, the thermosteric sea-level rise5,9,10,11,12,13,14,15,16. Patterns of interannual variability, in particular, differ among methods. Here we examine several sources of uncertainty that contribute to differences among OHCA curves from 1993 to 2008, focusing on the difficulties of correcting biases in expendable bathythermograph (XBT) data. XBT data constitute the majority of the in situ measurements of upper-ocean heat content from 1967 to 2002, and we find that the uncertainty due to choice of XBT bias correction dominates among-method variability in OHCA curves during our 1993–2008 study period. Accounting for multiple sources of uncertainty, a composite of several OHCA curves using different XBT bias corrections still yields a statistically significant linear warming trend for 1993–2008 of 0.64 W m-2 (calculated for the Earth’s entire surface area), with a 90-per-cent confidence interval of 0.53–0.75 W m-2.
- Published
- 2009
41. Equatorial Kelvin wave influences may reach the Bering Sea during 2002 to 2005
- Author
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Gregory C. Johnson and John M. Lyman
- Subjects
Anomaly (natural sciences) ,Equator ,Equatorial waves ,Sea-surface height ,symbols.namesake ,Wavelength ,Geophysics ,Oceanography ,Climatology ,symbols ,General Earth and Planetary Sciences ,Altimeter ,Kelvin wave ,Sea level ,Geology - Abstract
[1] The time-history of sea surface height (SSH) anomaly data from the TOPEX and Jason-1 altimeters is examined along the equator and northward following the west coast of the Americas. Along-track TOPEX and Jason-1 altimeter data are put into an alongshore–offshore coordinate system and then smoothed. This procedure increases the degrees of freedom in individual estimates of long-wavelength coastally trapped waves (CTWs) during times when both satellites are available (2002–2005). Equatorially trapped Kelvin waves are detected during the 2002–2003 El Nino. These Kelvin waves excite CTWs that travel northward along the west coast of the Americas. While CTWs associated with the 2002–2003 equatorial Kelvin waves are not always discernible along the entire coast, correlations of the coastal and equatorial SSH over the entire period of TOPEX and Jason-1 overlap show a clear phase progression. This phase progression implies remote influence of equatorial Kelvin waves that may reach as far north as the Bering Sea during the weak to moderate El Nino events that occurred from 2002 to 2005.
- Published
- 2008
42. Correction to 'Recent cooling of the upper ocean'
- Author
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John M. Lyman, Joshua K. Willis, Gregory C. Johnson, and John Gilson
- Subjects
Geophysics ,Climatology ,General Earth and Planetary Sciences ,Sampling error ,Bathythermograph ,Atmospheric sciences ,Geology ,Argo - Abstract
The recent cooling signal in the upper ocean reported by Lyman et al. [2006] is shown to be an artifact that was caused by a large cold bias discovered in a small fraction of Argo floats as well as a smaller but more prevalent warm bias in eXpendable BathyThermograph (XBT) data. These biases are both substantially larger than sampling errors estimated in Lyman et al. [2006].
- Published
- 2007
43. Recent cooling of the upper ocean
- Author
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Gregory C. Johnson, Joshua K. Willis, and John M. Lyman
- Subjects
Sea surface temperature ,Surface area ,Geophysics ,Climatology ,Anomaly (natural sciences) ,General Earth and Planetary Sciences ,Environmental science ,Sampling (statistics) ,Sampling error ,Global cooling ,Warming rate ,Ocean sampling - Abstract
We observe a net loss of 3.2 (± 1.1) × 10 22 J of heat from the upper ocean between 2003 and 2005. Using a broad array of in situ ocean measurements, we present annual estimates of global upper-ocean heat content anomaly from 1993 through 2005. Including the recent downturn, the average warming rate for the entire 13-year period is 0.33 ± 0.23 W/m 2 (of the Earth's total surface area). A new estimate of sampling error in the heat content record suggests that both the recent and previous global cooling events are significant and unlikely to be artifacts of inadequate ocean sampling.
- Published
- 2006
44. Comments on paper by Erik Eriksson, ‘Possible fluctuations in atmospheric carbon dioxide due to changes in the properties of the Sea’
- Author
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John M. Lyman
- Subjects
Atmospheric Science ,Carbon dioxide in Earth's atmosphere ,Ecology ,Paleontology ,Soil Science ,Forestry ,Aquatic Science ,Oceanography ,Geophysics ,Space and Planetary Science ,Geochemistry and Petrology ,Climatology ,Earth and Planetary Sciences (miscellaneous) ,Environmental science ,Earth-Surface Processes ,Water Science and Technology - Published
- 1964
45. Use of the Metric System and Celsius Scale
- Author
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John M. Lyman
- Subjects
Ninth ,Atmospheric Science ,Ecology ,Delegation ,media_common.quotation_subject ,Paleontology ,Soil Science ,Forestry ,Commission ,Aquatic Science ,Oceanography ,Geophysics ,Geography ,Space and Planetary Science ,Geochemistry and Petrology ,Earth and Planetary Sciences (miscellaneous) ,Metric system ,Physical geography ,Wilderness ,Earth-Surface Processes ,Water Science and Technology ,media_common - Abstract
At the second meeting of the Intergovernmental Oceanographic Commission, held at Paris, France, from September 20 to 29, 1962, the following resolution, introduced by the Japanese delegation, was adopted unanimously. A similar resolution was adopted by the Ninth Annual Eastern Pacific Oceanic Conference, held at Lake Wilderness, Washington, from October 3 to 5, 1962.
- Published
- 1963
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