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2. Seasonality of the Meridional Overturning Circulation in the subpolar North Atlantic

Author

Fu, Yao, Lozier, M. Susan, Biló, Tiago Carrilho, Bower, Amy S., Cunningham, Stuart A., Cyr, Frédéric, de Jong, M. Femke, deYoung, Brad, Drysdale, Lewis, Fraser, Neil, Fried, Nora, Furey, Heather H., Han, Guoqi, Handmann, Patricia, Holliday, N. Penny, Holte, James, Inall, Mark E., Johns, William E., Jones, Sam, Karstensen, Johannes, Li, Feili, Pacini, Astrid, Pickart, Robert S., Rayner, Darren, Straneo, Fiammetta, and Yashayaev, Igor

Published
2023
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4. MONITORING ALASKAN ARCTIC SHELF ECOSYSTEMS THROUGH COLLABORATIVE OBSERVATION NETWORKS

Author

Danielson, Seth L., Grebmeier, Jacqueline M., Iken, Katrin, Berchok, Catherine, Britt, Lyle, Dunton, Kenneth H., Eisner, Lisa, Farley, Edward V., Fujiwara, Amane, Hauser, Donna D.W., Itoh, Motoyo, Kikuchi, Takashi, Kotwicki, Stan, Kuletz, Kathy J., Mordy, Calvin W., Nishino, Shigeto, Peralta-Ferriz, Cecilia, Pickart, Robert S., Stabeno, Phyllis S., Stafford, Kathleen M., Whiting, Alex V., and Woodgate, Rebecca

Published
2022

7. The Pacific water flow branches in the eastern Chukchi Sea

Author

Pickart, Robert S., Lin, Peigen, Bahr, Frank, McRaven, Leah T., Huang, Jie, Pacini, Astrid, Arrigo, Kevin R., Ashjian, Carin J., Berchok, Catherine, Baumgartner, Mark F., Cho, Kyoung-Ho, Cooper, Lee W., Danielson, Seth L., Dasher, Douglas, Fuiwara, Amane, Gann, Jeanette, Grebmeier, Jacqueline M., He, Jianfeng, Hirawake, Toru, Itoh, Motoyo, Juranek, Lauren, Kikuchi, Takashi, Moore, G.W.K., Napp, Jeff, John Nelson, R., Nishino, Shigeto, Statscewich, Hank, Stabeno, Phyllis, Stafford, Kathleen M., Ueno, Hiromichi, Vagle, Svein, Weingartner, Thomas J., Williams, Bill, and Zimmermann, Sarah

Published
2023
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22. OVERTURNING IN THE SUBPOLAR NORTH ATLANTIC PROGRAM : A New International Ocean Observing System

Author

Lozier, M. Susan, Bacon, Sheldon, Bower, Amy S., Cunningham, Stuart A., de Jong, M. Femke, de Steur, Laura, deYoung, Brad, Fischer, Jürgen, Gary, Stefan F., Greenan, Blair J. W., Heimbach, Patrick, Holliday, Naomi P., Houpert, Loïc, Inall, Mark E., Johns, William E., Johnson, Helen L., Karstensen, Johannes, Li, Feili, Lin, Xiaopei, Mackay, Neill, Marshall, David P., Mercier, Herlé, Myers, Paul G., Pickart, Robert S., Pillar, Helen R., Straneo, Fiammetta, Thierry, Virginie, Weller, Robert A., Williams, Richard G., Wilson, Chris, Yang, Jiayan, Zhao, Jian, and Zika, Jan D.

Published
2017

28. Glacial Meltwater in the Current System of Southern Greenland.

Author

Beaird, Nicholas L., Straneo, Fiamma, Le Bras, Isabela, Pickart, Robert, and Jenkins, William J.

Subjects
MELTWATER, ATLANTIC meridional overturning circulation, GREENLAND ice, ICE sheets, OCEAN currents
Abstract

The Greenland Ice Sheet is losing mass at an accelerating pace, increasing its contribution to the freshwater input into the Nordic Seas and the subpolar North Atlantic. It has been proposed that this increased freshwater may impact the Atlantic Meridional Overturning Circulation by affecting the stratification of the convective regions of the North Atlantic and Nordic Seas. Observations of the transformation and pathways of meltwater from the Greenland Ice Sheet on the continental shelf and in the gyre interior, however, are lacking. Here, we report on noble gas derived observations of submarine meltwater distribution and transports in the East and West Greenland Current Systems of southern Greenland and around Cape Farewell. In southeast Greenland, submarine meltwater is concentrated in the East Greenland Coastal Current core with maximum concentrations of 0.8%, thus significantly diluted relative to fjord observations. It is found in water with density ranges from 1,024 to 1027.2 kg m−3 and salinity from 30.6 to 34, which extends as deep as 250 m and as far offshore as 60 km on the Greenland shelf. Submarine meltwater transport on the shelf averages 5.0 ± 1.6 mSv which, if representative of the mean annual transport, represents 60%–80% of the total solid ice discharge from East Greenland and suggests relatively little offshore export of meltwater east and upstream of Cape Farewell. The location of the meltwater transport maximum shifts toward the shelfbreak around Cape Farewell, positioning the meltwater for offshore flux in regions of known cross‐shelf exchange along the West Greenland coast. Plain Language Summary: The Greenland Ice Sheet is losing a lot of ice very quickly and this is causing more lightweight freshwater to flow into the North Atlantic Ocean. This extra freshwater could possibly influence the way that the surface and interior of the ocean interact, impacting global ocean currents. We do not have enough information about how the ice that is melting from Greenland is affecting the ocean, in part because we do not have many tools to observe where the meltwater goes. In this work, we made measurements with the best tools available to follow the ice melted from marine terminating glaciers as it travels around Greenland. We were able to make some of the most comprehensive direct measurements of the oceanic pathways of glacial meltwater in coastal Greenland. We found that the freshwater from Greenlandic glacier's submarine melted ice is not very concentrated when it gets to the ocean, but it does go deep and, at first, not too far away from the shore. The Greenland meltwater stays close to shore along the east coast up to Cape Farewell. However, meltwater moves farther from shore after that and may mix out into the open ocean from there. Key Points: Direct measurements of the pathways and fluxes of glacial meltwater in coastal GreenlandLittle offshore export of meltwater east and upstream of Cape FarewellMeltwater moves offshore toward shelfbreak around Cape Farewell [ABSTRACT FROM AUTHOR]

Published
2023
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29. Spatiotemporal transitions in Pseudo-nitzschia species assemblages and domoic acid along the Alaska coast

Author

Hubbard, Katherine A., primary, Villac, Maria Célia, additional, Chadwick, Christina, additional, DeSmidt, Alexandra A., additional, Flewelling, Leanne, additional, Granholm, April, additional, Joseph, Molly, additional, Wood, Taylor, additional, Fachon, Evangeline, additional, Brosnahan, Michael L., additional, Richlen, Mindy, additional, Pathare, Mrunmayee, additional, Stockwell, Dean, additional, Lin, Peigen, additional, Bouchard, Josée N., additional, Pickart, Robert, additional, and Anderson, Donald M., additional

Published
2023
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31. Coupled atmosphere‐ocean observations of a cold air outbreak and its impact on the Iceland Sea

Author

Renfrew, Ian A., Huang, Jie, Semper, Stefanie, Barrell, Christopher, Terpstra, Annick, Pickart, Robert S., Våge, Kjetil, Elvidge, Andrew D., Spengler, Thomas, Strehl, Anna‐Marie, Weiss, Alexandra, Renfrew, Ian A., Huang, Jie, Semper, Stefanie, Barrell, Christopher, Terpstra, Annick, Pickart, Robert S., Våge, Kjetil, Elvidge, Andrew D., Spengler, Thomas, Strehl, Anna‐Marie, and Weiss, Alexandra

Abstract

Marine cold air outbreaks are vigorous equatorward excursions of cold air over the ocean, responsible for the majority of wintertime oceanic heat loss from the subpolar seas of the North Atlantic. However, the impact of individual cold air outbreak (CAO) events on the ocean is poorly understood. Here we present the first coupled observations of the atmosphere and ocean during a wintertime CAO event, between 28 February and 13 March 2018, in the subpolar North Atlantic region. Comprehensive observations are presented from five aircraft flights, a research vessel, a meteorological buoy, a subsurface mooring, an ocean glider, and an Argo float. The CAO event starts abruptly with substantial changes in temperature, humidity, and wind throughout the atmospheric boundary layer. The CAO is well-mixed vertically and, away from the sea-ice edge, relatively homogeneous spatially. During the CAO peak, higher sensible heat fluxes occupy at least the lowest 200 m of the atmospheric boundary layer, while higher latent heat fluxes are confined to the surface layer. The response of the ocean to the CAO is spatially dependent. In the interior of the Iceland Sea the mixed layer cools, while in the boundary current region it warms. In both locations, the mixed layer deepens and becomes more saline. Combining our observations with one-dimensional mixed-layer modelling, we show that in the interior of the Iceland Sea, atmospheric forcing dominates the ocean response. In contrast, in the boundary current region lateral advection and mixing counteract the short-term impact of the atmospheric forcing. Time series observations of the late-winter period illustrate a highly variable ocean mixed layer, with lateral advection and mixing often masking the ocean's general cooling and deepening response to individual CAO events.

Published
2023

37. Surface meteorology and fluxes over the Iceland and Greenland Seas in ERA5 reanalysis: The impact of sea ice distribution

Author

Renfrew, Ian, Barrell, Chris, Elvidge, Andrew, Brooke, Jenn, Duscha, Christine, King, John, Kristiansen, Jorn, Lachlan Cope, Tom, Moore, Kent, Pickart, Robert, Reuder, Joachim, Sandu, irina, Sergeev, Denis, Terpstra, Annick, and Vage, Kjetil

Abstract

The Iceland and Greenland Seas are a crucial region for the climate system,being the headwaters of the lower limb of the Atlantic Meridional OverturningCirculation.Investigating the atmosphere–ocean–ice processes in this regionoften necessitates the use of meteorological reanalyses—a representation of theatmospheric state based on the assimilation of observations into a numericalweather prediction system. Knowing the quality of reanalysis products is vitalfor their proper use. Here we evaluate the surface-layer meteorology and surfaceturbulent fluxes in winter and spring for the latest reanalysis from theEuropean Centre for Medium-Range Weather Forecasts, i.e., ERA5. In situobservations from a meteorological buoy, a research vessel, and a researchaircraft during the Iceland–Greenland Seas Project provide unparalleled coverageof this climatically important region. The observations are independentof ERA5. They allow a comprehensive evaluation of the surface meteorologyand fluxes of these subpolar seas and, for the first time, a specific focus onthe marginal ice zone. Over the ice-free ocean, ERA5 generally compares wellto the observations of surface-layer meteorology and turbulent fluxes. However,over the marginal ice zone, the correspondence is noticeably less accurate:for example, the root-mean-square errors are significantly higher for surfacetemperature, wind speed, and surface sensible heat flux. The primary reasonfor the difference in reanalysis quality is an overly smooth sea-ice distributionin the surface boundary conditions used in ERA5. Particularly over themarginal ice zone, unrepresented variability and uncertainties in how to parameterizesurface exchange compromise the quality of the reanalyses. A parallelevaluation of higher-resolution forecast fields from the Met Office’s UnifiedModel corroborates these findings., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Published
2023

38. Eddy flux of Atlantic Water to the Eurasian Basin North of Svalbard

Author

Perez-Hernandez, M Dolores, Pickart, Robert S., Sundfjord, Arild, Ingvaldsen, Randi, Renner, Angelika HH, and Pavlov, Vladimir

Abstract

The Svalbard branch of the Atlantic Water (AW) flows eastward north of Svalbard carrying warm and salty waters along the slope of the Arctic Eurasian Basin. Recent studies have shown that this current is baroclinically unstable and sheds eddies into the basin. Here we use data from a mooring array deployed near 30°E between September 2012 and September 2013 to explore the eddies shed from the boundary current. The instrument coverage extended down to 1200‐m depth and meridionally to approximately 50 km offshore of the shelfbreak, which laterally bracketed the flow. The moorings contained conductivity-temperature-depth profilers that sampled the water column every 12 hours and acoustic Doppler current profilers that sampled the water column every hour. Eddies were present throughout the year and reached down to 600m depth, some of them embedded within the pycnocline. The study is carried out using two different methodologies to describe the eddies: an empirical orthogonal function analysis of the vertical sections of velocity, and case studies of eddy events in different seasons., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Published
2023

46. The Arctic Ocean's Changing Beaufort Gyre System: An Assessment of Current Understanding, Open Questions and Future Research Directions.

Author

Timmermans, Mary-Louise E. and Pickart, Robert S.

Subjects
*SEA ice, *OCEAN, *OPEN-ended questions, *RESEARCH questions, *ATMOSPHERIC boundary layer, *CLIMATE change models
Abstract

Changes in the ocean component of the Beaufort Gyre system are as considerable as its changing sea ice, including increases in freshwater and ocean heat content (reviewed by [19]). 21 Zhang, Y., M. Yamamoto-Kawai, and W. J. Williams, 2020: Two decades of ocean acidification in the surface waters of the Beaufort Gyre, Arctic Ocean: Effects of sea ice melt and retreat from 1997-2016. Keywords: Arctic; Sea ice; Ocean circulation; Climate EN Arctic Sea ice Ocean circulation Climate E1282 E1289 8 08/24/23 20230701 NES 230701 A Workshop on the Changing Beaufort Gyre System B I What i b : An international group of 50 scientists met in person to review and discuss the physical and biogeochemical aspects of the Arctic's Beaufort Gyre system, explore the open research questions, and make recommendations for future research directions and projects. The Beaufort Gyre is one of the fundamental sea ice and ocean circulation systems of the Arctic Ocean, located in a region that is exhibiting some of the most pronounced changes due to the warming climate; for example, the past two decades have seen the largest Arctic sea ice losses and ocean heat content increases in the Beaufort Gyre region and surrounding marginal seas, changes which have important consequences for ecosystems within and beyond the Arctic. [Extracted from the article]

Published
2023
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49. Paralytic shellfish toxins in Alaskan Arctic food webs during the anomalously warm ocean conditions of 2019 and estimated toxin doses to Pacific walruses and bowhead whales

Author

Lefebvre, Kathi A., primary, Fachon, Evangeline, additional, Bowers, Emily K., additional, Kimmel, David G., additional, Snyder, Jonathan A., additional, Stimmelmayr, Raphaela, additional, Grebmeier, Jacqueline M., additional, Kibler, Steve, additional, Ransom Hardison, D., additional, Anderson, Donald M., additional, Kulis, David, additional, Murphy, Jim, additional, Gann, Jeanette C., additional, Cooper, Dan, additional, Eisner, Lisa B., additional, Duffy-Anderson, Janet T., additional, Sheffield, Gay, additional, Pickart, Robert S., additional, Mounsey, Anna, additional, Willis, Maryjean L., additional, Stabeno, Phyllis, additional, and Siddon, Elizabeth, additional

Published
2022
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