Search

Your search keyword '"Howard, Dean"' showing total 164 results
Start Over Author "Howard, Dean"

Refine your results

more »

more »

more »

more »

more »
164 results on '"Howard, Dean"'

1. The Marginal Ice Zone as a dominant source region of atmospheric mercury during central Arctic summertime

Author

Yue, Fange, Angot, Hélène, Blomquist, Byron, Schmale, Julia, Hoppe, Clara J. M., Lei, Ruibo, Shupe, Matthew D., Zhan, Liyang, Ren, Jian, Liu, Hailong, Beck, Ivo, Howard, Dean, Jokinen, Tuija, Laurila, Tiia, Quéléver, Lauriane, Boyer, Matthew, Petäjä, Tuukka, Archer, Stephen, Bariteau, Ludovic, Helmig, Detlev, Hueber, Jacques, Jacobi, Hans-Werner, Posman, Kevin, and Xie, Zhouqing

Published
2023
Full Text
View/download PDF

2. Widespread detection of chlorine oxyacids in the Arctic atmosphere

Author

Tham, Yee Jun, Sarnela, Nina, Iyer, Siddharth, Li, Qinyi, Angot, Hélène, Quéléver, Lauriane L. J., Beck, Ivo, Laurila, Tiia, Beck, Lisa J., Boyer, Matthew, Carmona-García, Javier, Borrego-Sánchez, Ana, Roca-Sanjuán, Daniel, Peräkylä, Otso, Thakur, Roseline C., He, Xu-Cheng, Zha, Qiaozhi, Howard, Dean, Blomquist, Byron, Archer, Stephen D., Bariteau, Ludovic, Posman, Kevin, Hueber, Jacques, Helmig, Detlev, Jacobi, Hans-Werner, Junninen, Heikki, Kulmala, Markku, Mahajan, Anoop S., Massling, Andreas, Skov, Henrik, Sipilä, Mikko, Francisco, Joseph S., Schmale, Julia, Jokinen, Tuija, and Saiz-Lopez, Alfonso

Published
2023
Full Text
View/download PDF

3. How Experienced Students See: Perceptions of Engagement with Instructors

Author

Huff, Howard Dean

Abstract

Education has changed more in the last twenty years than in the previous 100 years. This fact is due to the onslaught of online learning opportunities through web 2.0 and 3.0 technologies that allow users to interact almost seamlessly with other people and content. Rapid change brings with it the potential for new challenges about how students learn effectively online and, therefore, there is need for research and discovery regarding what learners need to be successful in online learning environments. This research focused on the lack of understanding and definition on how online students perceive engagement between student and instructor, specifically from the students' lived experience within online learning environments. The purpose of this research was to discover how experienced online learners perceived their own engagement needs with online instructors. Experienced or veteran online learners were chosen as participants because they had experiences with multiple online teachers, so their perceptions of engagement were not based on the engagement practices of one teacher. The conceptual framework for this qualitative phenomenological study was social development theory with social constructivism providing the researcher with parameters for better understanding the lived experiences of all participants being interviewed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]

Published
2022

4. Substantial contribution of iodine to Arctic ozone destruction

Author

Benavent, Nuria, Mahajan, Anoop S., Li, Qinyi, Cuevas, Carlos A., Schmale, Julia, Angot, Hélène, Jokinen, Tuija, Quéléver, Lauriane L. J., Blechschmidt, Anne-Marlene, Zilker, Bianca, Richter, Andreas, Serna, Jesús A., Garcia-Nieto, David, Fernandez, Rafael P., Skov, Henrik, Dumitrascu, Adela, Simões Pereira, Patric, Abrahamsson, Katarina, Bucci, Silvia, Duetsch, Marina, Stohl, Andreas, Beck, Ivo, Laurila, Tiia, Blomquist, Byron, Howard, Dean, Archer, Stephen D., Bariteau, Ludovic, Helmig, Detlev, Hueber, Jacques, Jacobi, Hans-Werner, Posman, Kevin, Dada, Lubna, Daellenbach, Kaspar R., and Saiz-Lopez, Alfonso

Published
2022
Full Text
View/download PDF

5. Year-round trace gas measurements in the central Arctic during the MOSAiC expedition

Author

Angot, Hélène, Blomquist, Byron, Howard, Dean, Archer, Stephen, Bariteau, Ludovic, Beck, Ivo, Boyer, Matthew, Crotwell, Molly, Helmig, Detlev, Hueber, Jacques, Jacobi, Hans-Werner, Jokinen, Tuija, Kulmala, Markku, Lan, Xin, Laurila, Tiia, Madronich, Monica, Neff, Donald, Petäjä, Tuukka, Posman, Kevin, Quéléver, Lauriane, Shupe, Matthew D., Vimont, Isaac, and Schmale, Julia

Published
2022
Full Text
View/download PDF

8. Navajo Electrification for Sustainable Development: The Potential Economic and Social Benefits

Author

Bain, Craig, Ballentine, Crystal, DeSouza, Anil, Majure, Lisa, Howard, Dean, and Turek, Jill

Subjects
low population densities, potential success of a small business, self-contained solar systems
Abstract

Using data from the United States Census 1990, the Energy Information Administration estimated in 2000 that 36.8 percent of the 29,375 occupied housing units on the Navajo Nation lacked electricity. The Navajo Nation has very low population densities, and the large distances between homes make the cost of providing conventional sources of electricity prohibitive. Arizona Public Service, the primary provider of electricity in Arizona, estimates the cost of erecting power lines to be roughly $25,000 to $30,000 per mile, an impossible sum for most families in this region, where the unemployment rate hovers around 50 percent. Given the extremely low population densities, it is simply inconceivable that many houses could be connected to the power grid. More recent calculations, based on Census 2000 data, show that between 10,000 and 23,000 homes need some type of electricity provision system that is not connected to the grid. An estimate of 18,000 homes appears to be a reasonable current target figure (this number could very well increase as the population grows). The predicted cost of any program providing electricity and the associated appliances to these homes falls between $115 and $350 million. Using the baseline figure of 18,000 homes, the estimate is roughly $235 million. These are costs above the typical construction costs for the expected new housing units.The authors have completed an analysis of the potential success of a small business operating on the Navajo Nation installing self-contained solar systems, including battery storage, for these 18,000 homes. Several scenarios were analyzed, and the individual prices of the systems ranged from $10,000 to $19,000, depending on the size of the system and the level of retail markup.

Published
2004

10. Modelling the coupled mercury-halogen-ozone cycle in the central Arctic during spring

Author

Ahmed, Shaddy, Thomas, Jennie L, Angot, Hélène, Dommergue, Aurélien, Archer, Stephen D, Bariteau, Ludovic, Beck, Ivo, Benavent, Nuria, Blechschmidt, Anne-Marlene, Blomquist, Byron, Boyer, Matthew, Christensen, Jesper H, Dahlke, Sandro, Dastoor, Ashu, Helmig, Detlev, Howard, Dean, Jacobi, Hans-Werner, Jokinen, Tuija, Lapere, Rémy, Laurila, Tiia, Quéléver, Lauriane LJ, Richter, Andreas, Ryjkov, Andrei, Mahajan, Anoop S, Marelle, Louis, Pfaffhuber, Katrine Aspmo, Posman, Kevin, Rinke, Annette, Saiz-Lopez, Alfonso, Schmale, Julia, Skov, Henrik, Steffen, Alexandra, Stupple, Geoff, Stutz, Jochen, Travnikov, Oleg, Zilker, Bianca, Ahmed, Shaddy, Thomas, Jennie L, Angot, Hélène, Dommergue, Aurélien, Archer, Stephen D, Bariteau, Ludovic, Beck, Ivo, Benavent, Nuria, Blechschmidt, Anne-Marlene, Blomquist, Byron, Boyer, Matthew, Christensen, Jesper H, Dahlke, Sandro, Dastoor, Ashu, Helmig, Detlev, Howard, Dean, Jacobi, Hans-Werner, Jokinen, Tuija, Lapere, Rémy, Laurila, Tiia, Quéléver, Lauriane LJ, Richter, Andreas, Ryjkov, Andrei, Mahajan, Anoop S, Marelle, Louis, Pfaffhuber, Katrine Aspmo, Posman, Kevin, Rinke, Annette, Saiz-Lopez, Alfonso, Schmale, Julia, Skov, Henrik, Steffen, Alexandra, Stupple, Geoff, Stutz, Jochen, Travnikov, Oleg, and Zilker, Bianca

Abstract

Near-surface mercury and ozone depletion events occur in the lowest part of the atmosphere during Arctic spring. Mercury depletion is the first step in a process that transforms long-lived elemental mercury to more reactive forms within the Arctic that are deposited to the cryosphere, ocean, and other surfaces, which can ultimately get integrated into the Arctic food web. Depletion of both mercury and ozone occur due to the presence of reactive halogen radicals that are released from snow, ice, and aerosols. In this work, we added a detailed description of the Arctic atmospheric mercury cycle to our recently published version of the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem 4.3.3) that includes Arctic bromine and chlorine chemistry and activation/recycling on snow and aerosols. The major advantage of our modelling approach is the online calculation of bromine concentrations and emission/recycling that is required to simulate the hourly and daily variability of Arctic mercury depletion. We used this model to study coupling between reactive cycling of mercury, ozone, and bromine during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) spring season in 2020 and evaluated results compared to land-based, ship-based, and remote sensing observations. The model predicts that elemental mercury oxidation is driven largely by bromine chemistry and that particulate mercury is the major form of oxidized mercury. The model predicts that the majority (74%) of oxidized mercury deposited to land-based snow is re-emitted to the atmosphere as gaseous elemental mercury, while a minor fraction (4%) of oxidized mercury that is deposited to sea ice is re-emitted during spring. Our work demonstrates that hourly differences in bromine/ozone chemistry in the atmosphere must be considered to capture the springtime Arctic mercury cycle, including its integration into the cryosphere and ocean.

Published
2023

11. Low ozone dry deposition rates to sea ice during the MOSAiC field campaign: Implications for the Arctic boundary layer ozone budget

Author

Deming, Jody W, Miller, Lisa A, Barten, Johannes GM, Ganzeveld, Laurens N, Steeneveld, Gert-Jan, Blomquist, Byron W, Angot, Hélène, Archer, Stephen D, Bariteau, Ludovic, Beck, Ivo, Boyer, Matthew, von der Gathen, Peter, Helmig, Detlev, Howard, Dean, Hueber, Jacques, Jacobi, Hans-Werner, Jokinen, Tuija, Laurila, Tiia, Posman, Kevin M, Quéléver, Lauriane, Schmale, Julia, Shupe, Matthew D, Krol, Maarten C, Deming, Jody W, Miller, Lisa A, Barten, Johannes GM, Ganzeveld, Laurens N, Steeneveld, Gert-Jan, Blomquist, Byron W, Angot, Hélène, Archer, Stephen D, Bariteau, Ludovic, Beck, Ivo, Boyer, Matthew, von der Gathen, Peter, Helmig, Detlev, Howard, Dean, Hueber, Jacques, Jacobi, Hans-Werner, Jokinen, Tuija, Laurila, Tiia, Posman, Kevin M, Quéléver, Lauriane, Schmale, Julia, Shupe, Matthew D, and Krol, Maarten C

Abstract

Dry deposition to the surface is one of the main removal pathways of tropospheric ozone (O₃). We quantified for the first time the impact of O₃ deposition to the Arctic sea ice on the planetary boundary layer (PBL) O₃ concentration and budget using year-round flux and concentration observations from the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) campaign and simulations with a single-column atmospheric chemistry and meteorological model (SCM). Based on eddy-covariance O₃ surface flux observations, we find a median surface resistance on the order of 20,000 s m¯¹, resulting in a dry deposition velocity of approximately 0.005 cm s¯¹. This surface resistance is up to an order of magnitude larger than traditionally used values in many atmospheric chemistry and transport models. The SCM is able to accurately represent the yearly cycle, with maxima above 40 ppb in the winter and minima around 15 ppb at the end of summer. However, the observed springtime ozone depletion events are not captured by the SCM. In winter, the modelled PBL O₃ budget is governed by dry deposition at the surface mostly compensated by downward turbulent transport of O₃ towards the surface. Advection, which is accounted for implicitly by nudging to reanalysis data, poses a substantial, mostly negative, contribution to the simulated PBL O₃ budget in summer. During episodes with low wind speed (<5 m s¯¹) and shallow PBL (<50 m), the 7-day mean dry deposition removal rate can reach up to 1.0 ppb h¯¹. Our study highlights the importance of an accurate description of dry deposition to Arctic sea ice in models to quantify the current and future O₃ sink in the Arctic, impacting the tropospheric O₃ budget, which has been modified in the last century largely due to anthropogenic activities.

Published
2023

12. Widespread detection of chlorine oxyacids in the Arctic atmosphere

Author

National Natural Science Foundation of China, European Commission, Academy of Finland, University of Helsinki, National Science Foundation (US), Swiss National Science Foundation, Swiss Polar Institute, Ferring Pharmaceuticals, Fundación la Caixa, Ministerio de Ciencia e Innovación (España), Tham, Yee Jun [0000-0001-7924-5841], Sarnela, Nina [0000-0003-1874-3235], Iyer, Siddharth [0000-0001-5989-609X], Li, Qinyi [0000-0002-5146-5831], Angot, Hélène [0000-0003-4673-8249], Beck, Lisa J. [0000-0003-3700-5895], Carmona-García, Javier [0000-0001-5359-7240], Roca-Sanjuán, Daniel [0000-0001-6495-2770], Peräkylä, Otso [0000-0002-2089-0106], He, Xu-Cheng [0000-0002-7416-306X], Archer, Stephen D. [0000-0001-6054-2424], Jacobi, Hans-Werner [0000-0003-2230-3136], Junninen, Heikki [0000-0001-7178-9430], Kulmala, Markku [0000-0003-3464-7825], Mahajan, Anoop S. [0000-0002-2909-5432], Massling, Andreas [0000-0001-8046-2798], Skov, Henrik [0000-0003-1167-8696], Francisco, Joseph S. [0000-0002-5461-1486], Schmale, Julia [0000-0002-1048-7962], Jokinen, Tuija [0000-0002-1280-1396], Saiz-Lopez, A. [0000-0002-0060-1581], Tham, Yee Jun, Sarnela, Nina, Iyer, Siddharth, Li, Qinyi, Angot, Hélène, Quéléver, Lauriane L. J., Beck, Ivo, Laurila, Tiia, Beck, Lisa J., Boyer, Matthew, Carmona-García, Javier, Borrego-Sánchez, Ana, Roca-Sanjuán, Daniel, Peräkylä, Otso, Thakur, Roseline C., He, Xu-Cheng, Zha, Qiaozhi, Howard, Dean, Blomquist, Byron, Archer, Stephen D., Bariteau, Ludovic, Posman, Kevin, Hueber, Jacques, Helmig, Detlev, Jacobi, Hans-Werner, Junninen, Heikki, Kulmala, Markku, Mahajan, Anoop S., Massling, Andreas, Skov, Henrik, Sipilä, Mikko, Francisco, Joseph S., Schmale, Julia, Jokinen, Tuija, Saiz-Lopez, A., National Natural Science Foundation of China, European Commission, Academy of Finland, University of Helsinki, National Science Foundation (US), Swiss National Science Foundation, Swiss Polar Institute, Ferring Pharmaceuticals, Fundación la Caixa, Ministerio de Ciencia e Innovación (España), Tham, Yee Jun [0000-0001-7924-5841], Sarnela, Nina [0000-0003-1874-3235], Iyer, Siddharth [0000-0001-5989-609X], Li, Qinyi [0000-0002-5146-5831], Angot, Hélène [0000-0003-4673-8249], Beck, Lisa J. [0000-0003-3700-5895], Carmona-García, Javier [0000-0001-5359-7240], Roca-Sanjuán, Daniel [0000-0001-6495-2770], Peräkylä, Otso [0000-0002-2089-0106], He, Xu-Cheng [0000-0002-7416-306X], Archer, Stephen D. [0000-0001-6054-2424], Jacobi, Hans-Werner [0000-0003-2230-3136], Junninen, Heikki [0000-0001-7178-9430], Kulmala, Markku [0000-0003-3464-7825], Mahajan, Anoop S. [0000-0002-2909-5432], Massling, Andreas [0000-0001-8046-2798], Skov, Henrik [0000-0003-1167-8696], Francisco, Joseph S. [0000-0002-5461-1486], Schmale, Julia [0000-0002-1048-7962], Jokinen, Tuija [0000-0002-1280-1396], Saiz-Lopez, A. [0000-0002-0060-1581], Tham, Yee Jun, Sarnela, Nina, Iyer, Siddharth, Li, Qinyi, Angot, Hélène, Quéléver, Lauriane L. J., Beck, Ivo, Laurila, Tiia, Beck, Lisa J., Boyer, Matthew, Carmona-García, Javier, Borrego-Sánchez, Ana, Roca-Sanjuán, Daniel, Peräkylä, Otso, Thakur, Roseline C., He, Xu-Cheng, Zha, Qiaozhi, Howard, Dean, Blomquist, Byron, Archer, Stephen D., Bariteau, Ludovic, Posman, Kevin, Hueber, Jacques, Helmig, Detlev, Jacobi, Hans-Werner, Junninen, Heikki, Kulmala, Markku, Mahajan, Anoop S., Massling, Andreas, Skov, Henrik, Sipilä, Mikko, Francisco, Joseph S., Schmale, Julia, Jokinen, Tuija, and Saiz-Lopez, A.

Abstract

Chlorine radicals are strong atmospheric oxidants known to play an important role in the depletion of surface ozone and the degradation of methane in the Arctic troposphere. Initial oxidation processes of chlorine produce chlorine oxides, and it has been speculated that the final oxidation steps lead to the formation of chloric (HClO3) and perchloric (HClO4) acids, although these two species have not been detected in the atmosphere. Here, we present atmospheric observations of gas-phase HClO3 and HClO4. Significant levels of HClO3 were observed during springtime at Greenland (Villum Research Station), Ny-Ålesund research station and over the central Arctic Ocean, on-board research vessel Polarstern during the Multidisciplinary drifting Observatory for the Study of the Arctic Climate (MOSAiC) campaign, with estimated concentrations up to 7 × 106 molecule cm-3. The increase in HClO3, concomitantly with that in HClO4, was linked to the increase in bromine levels. These observations indicated that bromine chemistry enhances the formation of OClO, which is subsequently oxidized into HClO3 and HClO4 by hydroxyl radicals. HClO3 and HClO4 are not photoactive and therefore their loss through heterogeneous uptake on aerosol and snow surfaces can function as a previously missing atmospheric sink for reactive chlorine, thereby reducing the chlorine-driven oxidation capacity in the Arctic boundary layer. Our study reveals additional chlorine species in the atmosphere, providing further insights into atmospheric chlorine cycling in the polar environment.

Published
2023

13. Modelling the coupled mercury-halogen-ozone cycle in the central Arctic during spring

Author

Université Grenoble Alpes, European Commission, Centre National de la Recherche Scientifique (France), National Science Foundation (US), Swiss National Science Foundation, Swiss Polar Institute, National Oceanic and Atmospheric Administration (US), Academy of Finland, Ferring Pharmaceuticals, Danish Environmental Protection Agency, Government of Canada, German Research Foundation, Ahmed, Shaddy, Thomas, Jennie L., Angot, Hélène, Dommergue, Aurélien, Archer, Stephen D., Bariteau, Ludovic, Beck, Ivo, Benavent, Nuria, Blechschmidt, Anne Marlene, Blomquist, Byron, Boyer, Matthew, Christensen, Jesper H., Dahlke, Sandro, Dastoor, Ashu, Helmig, Detlev, Howard, Dean, Jacobi, Hans Werner, Jokinen, Tuija, Lapere, Rémy, Laurila, Tiia, Quéléver, Lauriane L.J., Richter, Andreas, Ryjkov, Andrei, Mahajan, Anoop S., Marelle, Louis, Pfaffhuber, Katrine Aspmo, Posman, Kevin, Rinke, Annette, Saiz-Lopez, A., Schmale, Julia, Skov, Henrik, Steffen, Alexandra, Stupple, Geoff, Stutz, Jochen, Travnikov, Oleg, Zilker, Bianca, Université Grenoble Alpes, European Commission, Centre National de la Recherche Scientifique (France), National Science Foundation (US), Swiss National Science Foundation, Swiss Polar Institute, National Oceanic and Atmospheric Administration (US), Academy of Finland, Ferring Pharmaceuticals, Danish Environmental Protection Agency, Government of Canada, German Research Foundation, Ahmed, Shaddy, Thomas, Jennie L., Angot, Hélène, Dommergue, Aurélien, Archer, Stephen D., Bariteau, Ludovic, Beck, Ivo, Benavent, Nuria, Blechschmidt, Anne Marlene, Blomquist, Byron, Boyer, Matthew, Christensen, Jesper H., Dahlke, Sandro, Dastoor, Ashu, Helmig, Detlev, Howard, Dean, Jacobi, Hans Werner, Jokinen, Tuija, Lapere, Rémy, Laurila, Tiia, Quéléver, Lauriane L.J., Richter, Andreas, Ryjkov, Andrei, Mahajan, Anoop S., Marelle, Louis, Pfaffhuber, Katrine Aspmo, Posman, Kevin, Rinke, Annette, Saiz-Lopez, A., Schmale, Julia, Skov, Henrik, Steffen, Alexandra, Stupple, Geoff, Stutz, Jochen, Travnikov, Oleg, and Zilker, Bianca

Abstract

Near-surface mercury and ozone depletion events occur in the lowest part of the atmosphere during Arctic spring. Mercury depletion is the first step in a process that transforms long-lived elemental mercury to more reactive forms within the Arctic that are deposited to the cryosphere, ocean, and other surfaces, which can ultimately get integrated into the Arctic food web. Depletion of both mercury and ozone occur due to the presence of reactive halogen radicals that are released from snow, ice, and aerosols. In this work, we added a detailed description of the Arctic atmospheric mercury cycle to our recently published version of the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem 4.3.3) that includes Arctic bromine and chlorine chemistry and activation/recycling on snow and aerosols. The major advantage of our modelling approach is the online calculation of bromine concentrations and emission/recycling that is required to simulate the hourly and daily variability of Arctic mercury depletion. We used this model to study coupling between reactive cycling of mercury, ozone, and bromine during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) spring season in 2020 and evaluated results compared to land-based, ship-based, and remote sensing observations. The model predicts that elemental mercury oxidation is driven largely by bromine chemistry and that particulate mercury is the major form of oxidized mercury. The model predicts that the majority (74%) of oxidized mercury deposited to land-based snow is re-emitted to the atmosphere as gaseous elemental mercury, while a minor fraction (4%) of oxidized mercury that is deposited to sea ice is re-emitted during spring. Our work demonstrates that hourly differences in bromine/ozone chemistry in the atmosphere must be considered to capture the springtime Arctic mercury cycle, including its integration into the cryosphere and ocean.

Published
2023

14. Low ozone dry deposition rates to sea ice during the MOSAiC field campaign: Implications for the Arctic boundary layer ozone budget

Author

Barten, Johannes G.M., Ganzeveld, Laurens N., Steeneveld, Gert-Jan, Blomquist, Byron W., Angot, Hélène, Archer, Stephen D., Bariteau, Ludovic, Beck, Ivo, Boyer, Matthew, Von der Gathen, Peter, Helmig, Detlev, Howard, Dean, Hueber, Jacques, Jacobi, Hans-Werner, Jokinen, Tuija, Laurila, Tiia, Posman, Kevin M., Quéléver, Lauriane, Schmale, Julia, Shupe, Matthew D., Krol, Maarten C., Barten, Johannes G.M., Ganzeveld, Laurens N., Steeneveld, Gert-Jan, Blomquist, Byron W., Angot, Hélène, Archer, Stephen D., Bariteau, Ludovic, Beck, Ivo, Boyer, Matthew, Von der Gathen, Peter, Helmig, Detlev, Howard, Dean, Hueber, Jacques, Jacobi, Hans-Werner, Jokinen, Tuija, Laurila, Tiia, Posman, Kevin M., Quéléver, Lauriane, Schmale, Julia, Shupe, Matthew D., and Krol, Maarten C.

Abstract

Dry deposition to the surface is one of the main removal pathways of tropospheric ozone (O3). We quantified for the first time the impact of O3 deposition to the Arctic sea ice on the planetary boundary layer (PBL) O3 concentration and budget using year-round flux and concentration observations from the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) campaign and simulations with a single-column atmospheric chemistry and meteorological model (SCM). Based on eddy-covariance O3 surface flux observations, we find a median surface resistance on the order of 20,000 s m−1, resulting in a dry deposition velocity of approximately 0.005 cm s−1. This surface resistance is up to an order of magnitude larger than traditionally used values in many atmospheric chemistry and transport models. The SCM is able to accurately represent the yearly cycle, with maxima above 40 ppb in the winter and minima around 15 ppb at the end of summer. However, the observed springtime ozone depletion events are not captured by the SCM. In winter, the modelled PBL O3 budget is governed by dry deposition at the surface mostly compensated by downward turbulent transport of O3 towards the surface. Advection, which is accounted for implicitly by nudging to reanalysis data, poses a substantial, mostly negative, contribution to the simulated PBL O3 budget in summer. During episodes with low wind speed (

Published
2023

15. New source mechanism for airborne particulate mercury in the central Arctic

Author

Schmale, Julia, primary, Angot, Helene, additional, Heutte, Benjamin, additional, Bergner, Nora, additional, Archer, Stephen, additional, Bariteau, Ludovic, additional, Beck, Ivo, additional, Blomquist, Byron, additional, Boyer, Matthew, additional, Frey, Markus, additional, Helmig, Detlev, additional, Howard, Dean, additional, Jacobi, Hans-Werner, additional, Jokinen, Tuija, additional, Laurila, Tiia, additional, Pernov, Jakob, additional, Posman, Kevin, additional, Pratt, Kerri, additional, and Quelever, Lauriane, additional

Published
2023
Full Text
View/download PDF

16. Low ozone dry deposition rates to sea ice during the MOSAiC field campaign: Implications for the Arctic boundary layer ozone budget

Author

Barten, Johannes G.M., primary, Ganzeveld, Laurens N., additional, Steeneveld, Gert-Jan, additional, Blomquist, Byron W., additional, Angot, Hélène, additional, Archer, Stephen D., additional, Bariteau, Ludovic, additional, Beck, Ivo, additional, Boyer, Matthew, additional, von der Gathen, Peter, additional, Helmig, Detlev, additional, Howard, Dean, additional, Hueber, Jacques, additional, Jacobi, Hans-Werner, additional, Jokinen, Tuija, additional, Laurila, Tiia, additional, Posman, Kevin M., additional, Quéléver, Lauriane, additional, Schmale, Julia, additional, Shupe, Matthew D., additional, and Krol, Maarten C., additional

Published
2023
Full Text
View/download PDF

17. Modelling the coupled mercury-halogen-ozone cycle in the central Arctic during spring

Author

Ahmed, Shaddy, primary, Thomas, Jennie L., additional, Angot, Hélène, additional, Dommergue, Aurélien, additional, Archer, Stephen D., additional, Bariteau, Ludovic, additional, Beck, Ivo, additional, Benavent, Nuria, additional, Blechschmidt, Anne-Marlene, additional, Blomquist, Byron, additional, Boyer, Matthew, additional, Christensen, Jesper H., additional, Dahlke, Sandro, additional, Dastoor, Ashu, additional, Helmig, Detlev, additional, Howard, Dean, additional, Jacobi, Hans-Werner, additional, Jokinen, Tuija, additional, Lapere, Rémy, additional, Laurila, Tiia, additional, Quéléver, Lauriane L. J., additional, Richter, Andreas, additional, Ryjkov, Andrei, additional, Mahajan, Anoop S., additional, Marelle, Louis, additional, Pfaffhuber, Katrine Aspmo, additional, Posman, Kevin, additional, Rinke, Annette, additional, Saiz-Lopez, Alfonso, additional, Schmale, Julia, additional, Skov, Henrik, additional, Steffen, Alexandra, additional, Stupple, Geoff, additional, Stutz, Jochen, additional, Travnikov, Oleg, additional, and Zilker, Bianca, additional

Published
2023
Full Text
View/download PDF

18. Substantial contribution of iodine to Arctic ozone destruction. Nature Geoscience, https://doi.org/10.1038/s41561-022-01018-w

Author

Benavent, Nuria, Mahajan, Anoop S., Li, Qinyi, Cuevas, Carlos A., Schmale, Julia, Angot, Hélène, Jokinen, Tuija, Quéléver, Lauriane L. J., Blechschmidt, Anne-Marlene, Zilker, Bianca, Richter , Andreas, Serna, Jesús A., Garcia-Nieto, David, Fernandez, Rafael P., Skov, Henrik, Dumitrascu, Adela, Pereir, Patric Simões, Abrahamsson, Katarina, Bucci , Silvia, Duetsch, Marina, Stohl, Andreas, Beck, Ivo, Laurila, Tiia, Blomquist, Byron, Howard, Dean, Archer, Stephen D., Bariteau, Ludovic, Helmig, Detlev, Hueber, Jacques, Jacobi, Hans-Werner, Posman, Kevin, Dada, Lubna, Daellenbach, Kaspar R., and Saiz-Lopez, Alfonso

Abstract

Cuevas, C.A. Schmale, J. Angot, H. Jokinen, T. Quéléver, L.L.J Blechschmidt, A.-M. Zilker, B. Richter, A. Serna, J.A. Garcia-Nieto, D. Fernandez, R.P. Skov, H. Dumitrascu, A. Pereira, P.S. Abrahamsson, K. Bucci, S. Dütsch, M. Stohl, A. Beck, I. Laurila, T. Blomquist, B. Howard, D. Archer, S Bariteau, L. Helmig, D. Hueber, J. Jacobi, H.-W. Posman, K. Dada, L. Daellenbach, K.R and Saiz-Lopez, A. (2022)

Published
2022
Full Text
View/download PDF

20. Overview of the MOSAiC expedition - Atmosphere

Author

Shupe, Matthew D., Rex, Markus, Blomquist, Byron, Persson, P. Ola G., Schmale, Julia, Uttal, Taneil, Althausen, Dietrich, Angot, Hélène, Archer, Stephen, Bariteau, Ludovic, Beck, Ivo, Bilberry, John, Bucci, Silvia, Buck, Clifton, Boyer, Matt, Brasseur, Zoé, Brooks, Ian M., Calmer, Radiance, Cassano, John, Castro, Vagner, Chu, David, Costa, David, Cox, Christopher J., Creamean, Jessie, Crewell, Susanne, Dahlke, Sandro, Damm, Ellen, de Boer, Gijs, Deckelmann, Holger, Dethloff, Klaus, Dütsch, Marina, Ebell, Kerstin, Ehrlich, André, Ellis, Jody, Engelmann, Ronny, Fong, Allison A., Frey, Markus M., Gallagher, Michael R., Ganzeveld, Laurens, Gradinger, Rolf, Graeser, Jürgen, Greenamyer, Vernon, Griesche, Hannes, Griffiths, Steele, Hamilton, Jonathan, Heinemann, Günther, Helmig, Detlev, Herber, Andreas, Heuzé, Céline, Hofer, Julian, Houchens, Todd, Howard, Dean, Inoue, Jun, Jacobi, Hans-Werner, Jaiser, Ralf, Jokinen, Tuija, Jourdan, Olivier, Jozef, Gina, King, Wessley, Kirchgaessner, Amelie, Klingebiel, Marcus, Krassovski, Misha, Krumpen, Thomas, Lampert, Astrid, Landing, William, Laurila, Tiia, Lawrence, Dale, Lonardi, Michael, Loose, Brice, Lüpkes, Christof, Maahn, Maximilian, Macke, Andreas, Maslowski, Wieslaw, Marsay, Christopher, Maturilli, Marion, Mech, Mario, Morris, Sara, Moser, Manuel, Nicolaus, Marcel, Ortega, Paul, Osborn, Jackson, Pätzold, Falk, Perovich, Donald K., Petäjä, Tuukka, Pilz, Christian, Pirazzini, Roberta, Posman, Kevin, Powers, Heath, Pratt, Kerri A., Preußer, Andreas, Quéléver, Lauriane, Radenz, Martin, Rabe, Benjamin, Rinke, Annette, Sachs, Torsten, Schulz, Alexander, Siebert, Holger, Silva, Tercio, Solomon, Amy, Sommerfeld, Anja, Spreen, Gunnar, Stephens, Mark, Stohl, Andreas, Svensson, Gunilla, Uin, Janek, Viegas, Juarez, Voigt, Christiane, von der Gathen, Peter, Wehner, Birgit, Welker, Jeffrey M., Wendisch, Manfred, Werner, Martin, Xie, ZhouQing, Yue, Fange, Shupe, Matthew D., Rex, Markus, Blomquist, Byron, Persson, P. Ola G., Schmale, Julia, Uttal, Taneil, Althausen, Dietrich, Angot, Hélène, Archer, Stephen, Bariteau, Ludovic, Beck, Ivo, Bilberry, John, Bucci, Silvia, Buck, Clifton, Boyer, Matt, Brasseur, Zoé, Brooks, Ian M., Calmer, Radiance, Cassano, John, Castro, Vagner, Chu, David, Costa, David, Cox, Christopher J., Creamean, Jessie, Crewell, Susanne, Dahlke, Sandro, Damm, Ellen, de Boer, Gijs, Deckelmann, Holger, Dethloff, Klaus, Dütsch, Marina, Ebell, Kerstin, Ehrlich, André, Ellis, Jody, Engelmann, Ronny, Fong, Allison A., Frey, Markus M., Gallagher, Michael R., Ganzeveld, Laurens, Gradinger, Rolf, Graeser, Jürgen, Greenamyer, Vernon, Griesche, Hannes, Griffiths, Steele, Hamilton, Jonathan, Heinemann, Günther, Helmig, Detlev, Herber, Andreas, Heuzé, Céline, Hofer, Julian, Houchens, Todd, Howard, Dean, Inoue, Jun, Jacobi, Hans-Werner, Jaiser, Ralf, Jokinen, Tuija, Jourdan, Olivier, Jozef, Gina, King, Wessley, Kirchgaessner, Amelie, Klingebiel, Marcus, Krassovski, Misha, Krumpen, Thomas, Lampert, Astrid, Landing, William, Laurila, Tiia, Lawrence, Dale, Lonardi, Michael, Loose, Brice, Lüpkes, Christof, Maahn, Maximilian, Macke, Andreas, Maslowski, Wieslaw, Marsay, Christopher, Maturilli, Marion, Mech, Mario, Morris, Sara, Moser, Manuel, Nicolaus, Marcel, Ortega, Paul, Osborn, Jackson, Pätzold, Falk, Perovich, Donald K., Petäjä, Tuukka, Pilz, Christian, Pirazzini, Roberta, Posman, Kevin, Powers, Heath, Pratt, Kerri A., Preußer, Andreas, Quéléver, Lauriane, Radenz, Martin, Rabe, Benjamin, Rinke, Annette, Sachs, Torsten, Schulz, Alexander, Siebert, Holger, Silva, Tercio, Solomon, Amy, Sommerfeld, Anja, Spreen, Gunnar, Stephens, Mark, Stohl, Andreas, Svensson, Gunilla, Uin, Janek, Viegas, Juarez, Voigt, Christiane, von der Gathen, Peter, Wehner, Birgit, Welker, Jeffrey M., Wendisch, Manfred, Werner, Martin, Xie, ZhouQing, and Yue, Fange

Abstract

With the Arctic rapidly changing, the needs to observe, understand, and model the changes are essential. To support these needs, an annual cycle of observations of atmospheric properties, processes, and interactions were made while drifting with the sea ice across the central Arctic during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition from October 2019 to September 2020. An international team designed and implemented the comprehensive program to document and characterize all aspects of the Arctic atmospheric system in unprecedented detail, using a variety of approaches, and across multiple scales. These measurements were coordinated with other observational teams to explore cross-cutting and coupled interactions with the Arctic Ocean, sea ice, and ecosystem through a variety of physical and biogeochemical processes. This overview outlines the breadth and complexity of the atmospheric research program, which was organized into 4 subgroups: atmospheric state, clouds and precipitation, gases and aerosols, and energy budgets. Atmospheric variability over the annual cycle revealed important influences from a persistent large-scale winter circulation pattern, leading to some storms with pressure and winds that were outside the interquartile range of past conditions suggested by long-term reanalysis. Similarly, the MOSAiC location was warmer and wetter in summer than the reanalysis climatology, in part due to its close proximity to the sea ice edge. The comprehensiveness of the observational program for characterizing and analyzing atmospheric phenomena is demonstrated via a winter case study examining air mass transitions and a summer case study examining vertical atmospheric evolution. Overall, the MOSAiC atmospheric program successfully met its objectives and was the most comprehensive atmospheric measurement program to date conducted over the Arctic sea ice. The obtained data will support a broad range of coupled-system

Published
2022

21. Overview of the MOSAiC expedition: Atmosphere

Author

Shupe, Matthew D, Rex, Markus, Blomquist, Byron, Persson, POG, Schmale, J, Uttal, Taneil, Althausen, Dietrich, Angot, Hélène, Archer, Stephen, Bariteau, Ludovic, Beck, Ivo, Bilberry, John, Boyer, Matt, Brasseur, Zoe, Brooks, Ian M, Bucci, Silvia, Buck, Clifton, Calmer, Radiance, Cassano, John, Castro, Vagner, Chu, David, Costa, David, Cox, Christopher J, Creamean, Jessie, Crewell, Susanne, Dahlke, Sandro, Damm, Ellen, De Boer, G, Deckelmann, Holger, Dethloff, Klaus, Dütsch, Marina, Ebell, Kerstin, Ehrlich, André, Ellis, Jody, Engelmann, Ronny, Fong, Allison A, Frey, Markus M, Gallagher, Michael R, Ganzeveld, L, Gradinger, Rolf, Graeser, Juergen, Greenamyer, Vernon, Griesche, Hannes, Griffiths, Steele, Hamilton, Jonathan, Heinemann, Günther, Helmig, Detlev, Herber, Andreas, Heuzé, Céline, Hofer, Julian, Houchens, Todd, Howard, Dean, Inoue, Jun, Jacobi, Hans-Werner, Jaiser, Ralf, Jokinen, Tuija, Jourdan, Olivier, Jozef, Gina, King, Wessley, Kirchgaessner, Amelie, Klingebiel, Marcus, Krassovski, Misha, Krumpen, Thomas, Lampert, Astrid, Landing, William M, Laurila, Tiia, Lawrence, Dale, Lonardi, Michael, Loose, Brice, Lüpkes, Christof, Maahn, Max, Macke, Andreas, Marsay, Christopher, Maslowski, Wieslaw, Maturilli, Marion, Mech, Mario, Morris, Sara, Moser, Manuel, Nicolaus, Marcel, Ortega, Paul, Osborn, Jackson, Pätzold, Falk, Perovich, Donald K, Petäjä, Tuukka, Pilz, Christian, Pirazzini, Roberta, Posman, Kevin, Powers, Heath, Pratt, Kerri A, Preußer, Andreas, Quelever, Lauriane, Rabe, Benjamin, Radenz, Martin, Rinke, Annette, Sachs, Torsten, Schulz, Alexander, Siebert, Holger, Silva, Tercio, Solomon, Amy, Sommerfeld, Anja, Spreen, Gunnar, Stevens, Mark, Stohl, Andreas, Svensson, Gunilla, Uin, Janek, Viegas, Juarez, Voigt, Christiane, von der Gathen, Peter, Wehner, Birgit, Welker, Jeffrey M, Wendisch, Manfred, Werner, Martin, Xie, ZhouQing, Yue, Fange, Shupe, Matthew D, Rex, Markus, Blomquist, Byron, Persson, POG, Schmale, J, Uttal, Taneil, Althausen, Dietrich, Angot, Hélène, Archer, Stephen, Bariteau, Ludovic, Beck, Ivo, Bilberry, John, Boyer, Matt, Brasseur, Zoe, Brooks, Ian M, Bucci, Silvia, Buck, Clifton, Calmer, Radiance, Cassano, John, Castro, Vagner, Chu, David, Costa, David, Cox, Christopher J, Creamean, Jessie, Crewell, Susanne, Dahlke, Sandro, Damm, Ellen, De Boer, G, Deckelmann, Holger, Dethloff, Klaus, Dütsch, Marina, Ebell, Kerstin, Ehrlich, André, Ellis, Jody, Engelmann, Ronny, Fong, Allison A, Frey, Markus M, Gallagher, Michael R, Ganzeveld, L, Gradinger, Rolf, Graeser, Juergen, Greenamyer, Vernon, Griesche, Hannes, Griffiths, Steele, Hamilton, Jonathan, Heinemann, Günther, Helmig, Detlev, Herber, Andreas, Heuzé, Céline, Hofer, Julian, Houchens, Todd, Howard, Dean, Inoue, Jun, Jacobi, Hans-Werner, Jaiser, Ralf, Jokinen, Tuija, Jourdan, Olivier, Jozef, Gina, King, Wessley, Kirchgaessner, Amelie, Klingebiel, Marcus, Krassovski, Misha, Krumpen, Thomas, Lampert, Astrid, Landing, William M, Laurila, Tiia, Lawrence, Dale, Lonardi, Michael, Loose, Brice, Lüpkes, Christof, Maahn, Max, Macke, Andreas, Marsay, Christopher, Maslowski, Wieslaw, Maturilli, Marion, Mech, Mario, Morris, Sara, Moser, Manuel, Nicolaus, Marcel, Ortega, Paul, Osborn, Jackson, Pätzold, Falk, Perovich, Donald K, Petäjä, Tuukka, Pilz, Christian, Pirazzini, Roberta, Posman, Kevin, Powers, Heath, Pratt, Kerri A, Preußer, Andreas, Quelever, Lauriane, Rabe, Benjamin, Radenz, Martin, Rinke, Annette, Sachs, Torsten, Schulz, Alexander, Siebert, Holger, Silva, Tercio, Solomon, Amy, Sommerfeld, Anja, Spreen, Gunnar, Stevens, Mark, Stohl, Andreas, Svensson, Gunilla, Uin, Janek, Viegas, Juarez, Voigt, Christiane, von der Gathen, Peter, Wehner, Birgit, Welker, Jeffrey M, Wendisch, Manfred, Werner, Martin, Xie, ZhouQing, and Yue, Fange

Abstract

With the Arctic rapidly changing, the needs to observe, understand, and model the changes are essential. To support these needs, an annual cycle of observations of atmospheric properties, processes, and interactions were made while drifting with the sea ice across the central Arctic during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition from October 2019 to September 2020. An international team designed and implemented the comprehensive program to document and characterize all aspects of the Arctic atmospheric system in unprecedented detail, using a variety of approaches, and across multiple scales. These measurements were coordinated with other observational teams to explore cross- cutting and coupled interactions with the Arctic Ocean, sea ice, and ecosystem through a variety of physical and biogeochemical processes. This overview outlines the breadth and complexity of the atmospheric research program, which was organized into 4 subgroups: atmospheric state, clouds and precipitation, gases and aerosols, and energy budgets. Atmospheric variability over the annual cycle revealed important influences from a persistent large-scale winter circulation pattern, leading to some storms with pressure and winds that were outside the interquartile range of past conditions suggested by long-term reanalysis. Similarly, the MOSAiC location was warmer and wetter in summer than the reanalysis climatology, in part due to its close proximity to the sea ice edge.The comprehensiveness of the observational program for characterizing and analyzing atmospheric phenomena is demonstrated via a winter case study examining air mass transitions and a summer case study examining vertical atmospheric evolution. Overall, the MOSAiC atmospheric program successfully met its objectives and was the most comprehensive atmospheric measurement program to date conducted over the Arctic sea ice. The obtained data will support a broad range of coupled-system

Published
2022

22. Trace gas and wind velocities at 10 hertz from the 10 meter MetCity tower during the MOSAiC Arctic drift campaign, 2019-2020

Author

Blomquist, Byron, Helmig, Detlev, Archer, Stephen, Ganzeveld, Laurens, Howard, Dean, Angot, Helene, Bariteau, Ludovic, Jacobi, Hans-Werner, Posman, Kevin, Hueber, Jacques, Blomquist, Byron, Helmig, Detlev, Archer, Stephen, Ganzeveld, Laurens, Howard, Dean, Angot, Helene, Bariteau, Ludovic, Jacobi, Hans-Werner, Posman, Kevin, and Hueber, Jacques

Abstract

Data are available for download at http://arcticdata.io/data/10.18739/A2R49GB1J These files are merged, 10 Hertz (Hz) measurements of 3 dimensional wind components (u,v,w) and dry air mole fractions of carbon dioxide (ppm) and methane (ppm). These are intended as raw files for computation of turbulent flux. The time lag between wind and gas measurements due to the long gas inlet has been corrected in this dataset (i.e. the gas concentration time series is time-shifted to synchronize the trace gas and vertical wind speed measurements). Files are provided in netCDF format with the standard CDF epoch timestamp (milliseconds since 01-Jan-1970 00:00Z) and year/month/day/hour/minute/second time vectors, to simplify date-time calculations. The wind coordinate system is right-handed and earth-relative, where u is northward velocity, v is westward velocity and w is upward velocity. Wind data is from the 10-meter ultrasonic anemometer on the MetCity tower. These data are available in original form from our collaborators (doi:10.18739/A2VM42Z5F) and are provided here in merged format with the gas data as a convenience to facilitate flux calculations.

Published
2022

23. Wind speed measurements with a 2-dimensional ultrasonic anemometer from the FS Polarstern bow tower, deployed during MOSAiC (Multidisciplinary Drifting Observatory for the Study of Arctic Climate) expedition, Arctic Circle, 2019-2020

Author

Blomquist, Byron, Archer, Stephen, Helmig, Detlev, Ganzeveld, Laurens, Howard, Dean, Angot, Helene, Bariteau, Ludovic, Jacobi, Hans-Werner, Posman, Kevin, Hueber, Jacques, Blomquist, Byron, Archer, Stephen, Helmig, Detlev, Ganzeveld, Laurens, Howard, Dean, Angot, Helene, Bariteau, Ludovic, Jacobi, Hans-Werner, Posman, Kevin, and Hueber, Jacques

Abstract

True and relative wind speed and direction measured from the bow of the research icebreaker FS Polarstern during the 2019-2020 Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) field program. These are minute-averaged values of 1 Hertz (Hz) raw measurements with an RM Young model 86004 heated, 2 Dimensional (2D) ultrasonic anemometer. The measurement location was ~18 meters (m) height on a triangular meteorological tower on the ship's bow, on a horizontal arm extending ~ 1.5m in front of the tower. Sensor heating prevented ice formation in almost all conditions, but there were a few periods of ice build-up in severe freezing rain or fog conditions. The north (N) orientation of the anemometer was in the direction of the ship's bow. True wind speed and direction are computed from relative winds and the ship heading. Due to obstructions from the ship's superstructure, measurements for relative wind directions beyond +/- 130 degrees from the bow are not accurate and subject to high variability. Measurements over the remaining wind sector (+/- 120 deg from the bow) are slightly distorted by the divergence of streamlines over the ship. As a convenience to users, ship navigation parameters (latitude, longitude, speed-over-ground, course-over-ground, and heading) are provided. The archives of ship navigation and meteorological data from PANGEA are the original sources for all navigation parameters (https://doi.org/10.1594/PANGAEA.935221, https://doi.org/10.1594/PANGAEA.935222, https://doi.org/10.1594/PANGAEA.935223, https://doi.org/10.1594/PANGAEA.935224, https://doi.org/10.1594/PANGAEA.935225).

Published
2022

24. Overview of the MOSAiC expedition-Atmosphere INTRODUCTION

Author

Shupe, Matthew D., Rex, Markus, Blomquist, Byron, Persson, P. Ola G., Schmale, Julia, Uttal, Taneil, Althausen, Dietrich, Angot, Helene, Archer, Stephen, Bariteau, Ludovic, Beck, Ivo, Bilberry, John, Bucci, Silvia, Buck, Clifton, Boyer, Matt, Brasseur, Zoe, Brooks, Ian M., Calmer, Radiance, Cassano, John, Castro, Vagner, Chu, David, Costa, David, Cox, Christopher J., Creamean, Jessie, Crewell, Susanne, Dahlke, Sandro, Damm, Ellen, de Boer, Gijs, Deckelmann, Holger, Dethloff, Klaus, Duetsch, Marina, Ebell, Kerstin, Ehrlich, Andre, Ellis, Jody, Engelmann, Ronny, Fong, Allison A., Frey, Markus M., Gallagher, Michael R., Ganzeveld, Laurens, Gradinger, Rolf, Graeser, Juergen, Greenamyer, Vernon, Griesche, Hannes, Griffiths, Steele, Hamilton, Jonathan, Heinemann, Guenther, Helmig, Detlev, Herber, Andreas, Heuze, Celine, Hofer, Julian, Houchens, Todd, Howard, Dean, Inoue, Jun, Jacobi, Hans-Werner, Jaiser, Ralf, Jokinen, Tuija, Jourdan, Olivier, Jozef, Gina, King, Wessley, Kirchgaessner, Amelie, Klingebiel, Marcus, Krassovski, Misha, Krumpen, Thomas, Lampert, Astrid, Landing, William, Laurila, Tiia, Lawrence, Dale, Lonardi, Michael, Loose, Brice, Luepkes, Christof, Maahn, Maximilian, Macke, Andreas, Maslowski, Wieslaw, Marsay, Christopher, Maturilli, Marion, Mech, Mario, Morris, Sara, Moser, Manuel, Nicolaus, Marcel, Ortega, Paul, Osborn, Jackson, Paetzold, Falk, Perovich, Donald K., Petaja, Tuukka, Pilz, Christian, Pirazzini, Roberta, Posman, Kevin, Powers, Heath, Pratt, Kerri A., Preusser, Andreas, Quelever, Lauriane, Radenz, Martin, Rabe, Benjamin, Rinke, Annette, Sachs, Torsten, Schulz, Alexander, Siebert, Holger, Silva, Tercio, Solomon, Amy, Sommerfeld, Anja, Spreen, Gunnar, Stephens, Mark, Stohl, Andreas, Svensson, Gunilla, Uin, Janek, Viegas, Juarez, Voigt, Christiane, von der Gathen, Peter, Wehner, Birgit, Welker, Jeffrey M., Wendisch, Manfred, Werner, Martin, Xie, ZhouQing, Yue, Fange, Shupe, Matthew D., Rex, Markus, Blomquist, Byron, Persson, P. Ola G., Schmale, Julia, Uttal, Taneil, Althausen, Dietrich, Angot, Helene, Archer, Stephen, Bariteau, Ludovic, Beck, Ivo, Bilberry, John, Bucci, Silvia, Buck, Clifton, Boyer, Matt, Brasseur, Zoe, Brooks, Ian M., Calmer, Radiance, Cassano, John, Castro, Vagner, Chu, David, Costa, David, Cox, Christopher J., Creamean, Jessie, Crewell, Susanne, Dahlke, Sandro, Damm, Ellen, de Boer, Gijs, Deckelmann, Holger, Dethloff, Klaus, Duetsch, Marina, Ebell, Kerstin, Ehrlich, Andre, Ellis, Jody, Engelmann, Ronny, Fong, Allison A., Frey, Markus M., Gallagher, Michael R., Ganzeveld, Laurens, Gradinger, Rolf, Graeser, Juergen, Greenamyer, Vernon, Griesche, Hannes, Griffiths, Steele, Hamilton, Jonathan, Heinemann, Guenther, Helmig, Detlev, Herber, Andreas, Heuze, Celine, Hofer, Julian, Houchens, Todd, Howard, Dean, Inoue, Jun, Jacobi, Hans-Werner, Jaiser, Ralf, Jokinen, Tuija, Jourdan, Olivier, Jozef, Gina, King, Wessley, Kirchgaessner, Amelie, Klingebiel, Marcus, Krassovski, Misha, Krumpen, Thomas, Lampert, Astrid, Landing, William, Laurila, Tiia, Lawrence, Dale, Lonardi, Michael, Loose, Brice, Luepkes, Christof, Maahn, Maximilian, Macke, Andreas, Maslowski, Wieslaw, Marsay, Christopher, Maturilli, Marion, Mech, Mario, Morris, Sara, Moser, Manuel, Nicolaus, Marcel, Ortega, Paul, Osborn, Jackson, Paetzold, Falk, Perovich, Donald K., Petaja, Tuukka, Pilz, Christian, Pirazzini, Roberta, Posman, Kevin, Powers, Heath, Pratt, Kerri A., Preusser, Andreas, Quelever, Lauriane, Radenz, Martin, Rabe, Benjamin, Rinke, Annette, Sachs, Torsten, Schulz, Alexander, Siebert, Holger, Silva, Tercio, Solomon, Amy, Sommerfeld, Anja, Spreen, Gunnar, Stephens, Mark, Stohl, Andreas, Svensson, Gunilla, Uin, Janek, Viegas, Juarez, Voigt, Christiane, von der Gathen, Peter, Wehner, Birgit, Welker, Jeffrey M., Wendisch, Manfred, Werner, Martin, Xie, ZhouQing, and Yue, Fange

Abstract

With the Arctic rapidly changing, the needs to observe, understand, and model the changes are essential. To support these needs, an annual cycle of observations of atmospheric properties, processes, and interactions were made while drifting with the sea ice across the central Arctic during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition from October 2019 to September 2020. An international team designed and implemented the comprehensive program to document and characterize all aspects of the Arctic atmospheric system in unprecedented detail, using a variety of approaches, and across multiple scales. These measurements were coordinated with other observational teams to explore crosscutting and coupled interactions with the Arctic Ocean, sea ice, and ecosystem through a variety of physical and biogeochemical processes. This overview outlines the breadth and complexity of the atmospheric research program, which was organized into 4 subgroups: atmospheric state, clouds and precipitation, gases and aerosols, and energy budgets. Atmospheric variability over the annual cycle revealed important influences from a persistent large-scale winter circulation pattern, leading to some storms with pressure and winds that were outside the interquartile range of past conditions suggested by long-term reanalysis. Similarly, the MOSAiC location was warmer and wetter in summer than the reanalysis climatology, in part due to its close proximity to the sea ice edge. The comprehensiveness of the observational program for characterizing and analyzing atmospheric phenomena is demonstrated via a winter case study examining air mass transitions and a summer case study examining vertical atmospheric evolution. Overall, the MOSAiC atmospheric program successfully met its objectives and was the most comprehensive atmospheric measurement program to date conducted over the Arctic sea ice. The obtained data will support a broad range of coupled-system s

Published
2022

25. Substantial contribution of iodine to Arctic ozone destruction

Author

European Commission, Consejo Superior de Investigaciones Científicas (España), Academy of Finland, Ministry of Earth Sciences (India), Swiss National Science Foundation, Swiss Polar Institute, National Science Foundation (US), Ferring Pharmaceuticals, German Research Foundation, Mahajan, Anoop S. [0000-0002-2909-5432], Li, Qinyi [0000-0002-5146-5831], Cuevas, Carlos A. [0000-0002-9251-5460], Schmale, Julia [0000-0002-1048-7962], Angot, Hélène [0000-0003-4673-8249], Richter, Andreas [0000-0003-3339-212X], Fernandez, Rafael P. [0000-0002-4114-5500], Skov, Henrik [0000-0003-1167-8696], Bucci, Silvia [0000-0002-6251-9444], Duetsch, Marina [0000-0002-1128-4198], Stohl, Andreas [0000-0002-2524-5755], Archer, Stephen D. [0000-0001-6054-2424], Dada, Lubna [0000-0003-1105-9043], Daellenbach, Kaspar R. [0000-0003-1246-6396], Saiz-Lopez, A. [0000-0002-0060-1581], Benavent, Nuria, Mahajan, Anoop S., Li, Qinyi, Cuevas, Carlos A., Schmale, Julia, Angot, Hélène, Jokinen, Tuija, Quéléver, Lauriane L.J., Blechschmidt, Anne Marlene, Zilker, Bianca, Richter, Andreas, Serna, Jesús A., García-Nieto, D., Fernández, Rafael P., Skov, Henrik, Dumitrascu, Adela, Simões Pereira, Patric, Abrahamsson, Katarina, Bucci, Silvia, Duetsch, Marina, Stohl, Andreas, Beck, Ivo, Laurila, Tiia, Blomquist, Byron, Howard, Dean, Archer, Stephen D., Bariteau, Ludovic, Helmig, Detlev, Hueber, Jacques, Jacobi, Hans Werner, Posman, Kevin, Dada, Lubna, Daellenbach, Kaspar R., Saiz-Lopez, A., European Commission, Consejo Superior de Investigaciones Científicas (España), Academy of Finland, Ministry of Earth Sciences (India), Swiss National Science Foundation, Swiss Polar Institute, National Science Foundation (US), Ferring Pharmaceuticals, German Research Foundation, Mahajan, Anoop S. [0000-0002-2909-5432], Li, Qinyi [0000-0002-5146-5831], Cuevas, Carlos A. [0000-0002-9251-5460], Schmale, Julia [0000-0002-1048-7962], Angot, Hélène [0000-0003-4673-8249], Richter, Andreas [0000-0003-3339-212X], Fernandez, Rafael P. [0000-0002-4114-5500], Skov, Henrik [0000-0003-1167-8696], Bucci, Silvia [0000-0002-6251-9444], Duetsch, Marina [0000-0002-1128-4198], Stohl, Andreas [0000-0002-2524-5755], Archer, Stephen D. [0000-0001-6054-2424], Dada, Lubna [0000-0003-1105-9043], Daellenbach, Kaspar R. [0000-0003-1246-6396], Saiz-Lopez, A. [0000-0002-0060-1581], Benavent, Nuria, Mahajan, Anoop S., Li, Qinyi, Cuevas, Carlos A., Schmale, Julia, Angot, Hélène, Jokinen, Tuija, Quéléver, Lauriane L.J., Blechschmidt, Anne Marlene, Zilker, Bianca, Richter, Andreas, Serna, Jesús A., García-Nieto, D., Fernández, Rafael P., Skov, Henrik, Dumitrascu, Adela, Simões Pereira, Patric, Abrahamsson, Katarina, Bucci, Silvia, Duetsch, Marina, Stohl, Andreas, Beck, Ivo, Laurila, Tiia, Blomquist, Byron, Howard, Dean, Archer, Stephen D., Bariteau, Ludovic, Helmig, Detlev, Hueber, Jacques, Jacobi, Hans Werner, Posman, Kevin, Dada, Lubna, Daellenbach, Kaspar R., and Saiz-Lopez, A.

Abstract

Unlike bromine, the effect of iodine chemistry on the Arctic surface ozone budget is poorly constrained. We present ship-based measurements of halogen oxides in the high Arctic boundary layer from the sunlit period of March to October 2020 and show that iodine enhances springtime tropospheric ozone depletion. We find that chemical reactions between iodine and ozone are the second highest contributor to ozone loss over the study period, after ozone photolysis-initiated loss and ahead of bromine.

Published
2022

26. Aspects of the biogeochemical cycling of mercury in Australia and the Southern Hemisphere

Author

Howard, Dean

Subjects
Other education not elsewhere classified
Abstract

The increase in levels of mercury in the environment is a truly global concern, recognised in the preparation and signing of the Minamata Convention on Mercury by 128 countries in 2010, and its enacting into force in 2017. The global nature of the problem lies in the persistence of mercury in the environment, leading to distribution of this neurotoxin to regions far-removed from sources, be they natural or anthropogenic. Understanding of the biogeochemical cycling of mercury is critical in order to estimate the legacy of previously emitted mercury, and to assess the effectiveness of control measures designed to decrease releases to the environment. This biogeochemical cycling is a complex system of processes, as the unique physicochemical properties of mercury allow for constant exchange between atmospheric, aquatic, terrestrial and biological reservoirs. Variation to rates, magnitudes and directions of this exchange take place across temporal and spatial scales, necessitating an increase in the number of biogeochemical cycling investigations implemented across the globe. Investigations such as these are limited in the context of the Australian environment. Modelling efforts have taken place to quantify and characterise biogeochemical cycling in Australia, though these are based on field and laboratory parameterisations undertaken elsewhere around the globe, and may not be suitably applicable to Australia's unique environs. Large, sparsely-populated and girt by sea, Australia is relatively unimpacted by local anthropogenic emissions of mercury. Instead, sources of mercury to this island continent are thought to be dominated by long-range transport, particularly through the atmosphere. Despite this, no long-term monitoring datasets of atmospheric mercury exist over Australia. This thesis presents the first multi-year investigations into atmospheric mercury levels in Australia. These investigations take place at two locations spanning the breadth of Australia's climate zones - one in tropical Northern Territory and the other in temperate Tasmania. Comparison between the two suggests that atmospheric mercury concentrations are largely congruous, despite very different source types and source regions. Further comparison with similar datasets taken elsewhere suggests this is broadly the case for the Southern Hemisphere in general, and that the concentration of atmospheric mercury is lower than previously believed. In this context, this thesis also investigates two important aspects regarding the natural biogeochemical cycling of mercury - delivery of atmospheric mercury to vegetation communities, and its release from these communities as a result of biomass burning. In both cases it is found that exchange of mercury is lower than previously believed, and that storage of mercury in Australian vegetation is up to 90 % lower than parameters currently used in biogeochemical modelling efforts. Depletion of ambient elemental mercury as a result of surface deposition under stable nocturnal boundary layers was observed at two locations, and throughout the year at one of these. Re-emission in the following morning at both sites provides further evidence for the prompt recycling process of atmospheric mercury transport. These investigations represent a first step in developing parameterisations unique to the Australian continent, and will serve as part of the wider global effort to monitor and mitigate the impacts of mercury on both humans and the natural environment.

Published
2022
Full Text
View/download PDF

28. Overview of the MOSAiC expedition: Atmosphere

Author

Shupe, Matthew D., primary, Rex, Markus, additional, Blomquist, Byron, additional, Persson, P. Ola G., additional, Schmale, Julia, additional, Uttal, Taneil, additional, Althausen, Dietrich, additional, Angot, Hélène, additional, Archer, Stephen, additional, Bariteau, Ludovic, additional, Beck, Ivo, additional, Bilberry, John, additional, Bucci, Silvia, additional, Buck, Clifton, additional, Boyer, Matt, additional, Brasseur, Zoé, additional, Brooks, Ian M., additional, Calmer, Radiance, additional, Cassano, John, additional, Castro, Vagner, additional, Chu, David, additional, Costa, David, additional, Cox, Christopher J., additional, Creamean, Jessie, additional, Crewell, Susanne, additional, Dahlke, Sandro, additional, Damm, Ellen, additional, de Boer, Gijs, additional, Deckelmann, Holger, additional, Dethloff, Klaus, additional, Dütsch, Marina, additional, Ebell, Kerstin, additional, Ehrlich, André, additional, Ellis, Jody, additional, Engelmann, Ronny, additional, Fong, Allison A., additional, Frey, Markus M., additional, Gallagher, Michael R., additional, Ganzeveld, Laurens, additional, Gradinger, Rolf, additional, Graeser, Jürgen, additional, Greenamyer, Vernon, additional, Griesche, Hannes, additional, Griffiths, Steele, additional, Hamilton, Jonathan, additional, Heinemann, Günther, additional, Helmig, Detlev, additional, Herber, Andreas, additional, Heuzé, Céline, additional, Hofer, Julian, additional, Houchens, Todd, additional, Howard, Dean, additional, Inoue, Jun, additional, Jacobi, Hans-Werner, additional, Jaiser, Ralf, additional, Jokinen, Tuija, additional, Jourdan, Olivier, additional, Jozef, Gina, additional, King, Wessley, additional, Kirchgaessner, Amelie, additional, Klingebiel, Marcus, additional, Krassovski, Misha, additional, Krumpen, Thomas, additional, Lampert, Astrid, additional, Landing, William, additional, Laurila, Tiia, additional, Lawrence, Dale, additional, Lonardi, Michael, additional, Loose, Brice, additional, Lüpkes, Christof, additional, Maahn, Maximilian, additional, Macke, Andreas, additional, Maslowski, Wieslaw, additional, Marsay, Christopher, additional, Maturilli, Marion, additional, Mech, Mario, additional, Morris, Sara, additional, Moser, Manuel, additional, Nicolaus, Marcel, additional, Ortega, Paul, additional, Osborn, Jackson, additional, Pätzold, Falk, additional, Perovich, Donald K., additional, Petäjä, Tuukka, additional, Pilz, Christian, additional, Pirazzini, Roberta, additional, Posman, Kevin, additional, Powers, Heath, additional, Pratt, Kerri A., additional, Preußer, Andreas, additional, Quéléver, Lauriane, additional, Radenz, Martin, additional, Rabe, Benjamin, additional, Rinke, Annette, additional, Sachs, Torsten, additional, Schulz, Alexander, additional, Siebert, Holger, additional, Silva, Tercio, additional, Solomon, Amy, additional, Sommerfeld, Anja, additional, Spreen, Gunnar, additional, Stephens, Mark, additional, Stohl, Andreas, additional, Svensson, Gunilla, additional, Uin, Janek, additional, Viegas, Juarez, additional, Voigt, Christiane, additional, von der Gathen, Peter, additional, Wehner, Birgit, additional, Welker, Jeffrey M., additional, Wendisch, Manfred, additional, Werner, Martin, additional, Xie, ZhouQing, additional, and Yue, Fange, additional

Published
2022
Full Text
View/download PDF

39. Smoke Emission and Transport Modelling Report 102

Author

Cope, Martin, Sunhee Lee, Meyer, Mick, Reisen, Fabienne, Trindade, Camilla, Sullivan, Andrew, Surawski, Nicholas, Wain, Alan, Smith, David, Ebert, Beth, C. J. Weston, Volkova, Liubov, Tolhurst, Kevin, Duff, Thomas, Walsh, Sean, Tapper, Nigel, Harris, Sarah, Rudiger, Chris, Holmes, Alex, Kilinc, Musa, Paton-Walsh, Clare, Guerette, Elise, Desservettaz, Maximilien, Edwards, Grant, Macsween, Katrina, and Howard, Dean

Published
2019
Full Text
View/download PDF

47. Global evaluation and calibration of a passive air sampler for gaseous mercury

Author

McLagan, David S., primary, Mitchell, Carl P. J., additional, Steffen, Alexandra, additional, Hung, Hayley, additional, Shin, Cecilia, additional, Stupple, Geoff W., additional, Olson, Mark L., additional, Luke, Winston T., additional, Kelley, Paul, additional, Howard, Dean, additional, Edwards, Grant C., additional, Nelson, Peter F., additional, Xiao, Hang, additional, Sheu, Guey-Rong, additional, Dreyer, Annekatrin, additional, Huang, Haiyong, additional, Abdul Hussain, Batual, additional, Lei, Ying D., additional, Tavshunsky, Ilana, additional, and Wania, Frank, additional

Published
2018
Full Text
View/download PDF

48. Genetic susceptibility for chronic lymphocytic leukemia among Chinese in Hong Kong

Author

Qing Lan, Stephen J. Chanock, Raymond Liang, Lisa L. P. Siu, Mark P. Purdue, Meredith Yeager, Jeff Yuenger, Wing Y. Au, Jovic Tse, Min Shen, Howard Dean Hosgood, Nathaniel Rothman, and Kit Fai Wong

Subjects
Chronic lymphocytic leukemia, Hematology, General Medicine, Odds ratio, Biology, medicine.disease, Genetic analysis, Confidence interval, hemic and lymphatic diseases, Immunology, Genetic variation, medicine, Genetic predisposition, Allele, Allele frequency
Abstract

The genetic basis of chronic lymphocytic leukemia (CLL) has not been fully elucidated to date. Although it is the most common haematological malignancy in Caucasians, it is uncommon among Asians. A recent genome-wide scan of CLL in Caucasians, which was carried out in the UK, identified six variants showing strong association. We attempted to replicate these findings in 71 patients with CLL and 1273 controls in Hong Kong Chinese. Three of the six variants were significantly associated with CLL. The rs872071 variant (Odds Ratio (95% Confidence Interval) = 1.78 (1.25-2.53), P = 0.0013) in the IRF4 gene region showed the strongest association, similar to that reported in the UK study. Polymorphisms in SP140 and ACOXL were also associated with risk of CLL. Further, the mean allele frequencies of the six variants were moderately (59%) to extremely (0.5%) lower in the Chinese population compared with Caucasians. These results suggest that variants in three loci may contribute to risk of CLL among Chinese.

Published
2010
Full Text
View/download PDF

49. Supplementary material to "Global evaluation and calibration of a passive air sampler for gaseous mercury"

Author

McLagan, David S., primary, Mitchell, Carl P. J., additional, Steffen, Alexandra, additional, Hung, Hayley, additional, Shin, Cecilia, additional, Stupple, Geoff W., additional, Olson, Mark L., additional, Luke, Winston T., additional, Kelley, Paul, additional, Howard, Dean, additional, Edwards, Grant C., additional, Nelson, Peter F., additional, Xiao, Hang, additional, Sheu, Guey-Rong, additional, Dreyer, Annekatrin, additional, Huang, Haiyong, additional, Abdul Hussain, Batual, additional, Lei, Ying D., additional, Tavshunsky, Ilana, additional, and Wania, Frank, additional

Published
2018
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results