Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Renfrew, I. A., Pickart, R. S., Vage, K., Moore, G. W. K., Bracegirdle, T. J., Elvidge, A. D., Jeansson, E., Lachlan-Cope, T., McRaven, L. T., Papritz, L., Reuder, J., Sodemann, H., Terpstra, A., Waterman, S., Valdimarsson, H., Weiss, A., Almansi, M., Bahr, F., Brakstad, A., Barrell, C., Brooke, J. K., Brooks, B. J., Brooks, I. M., Brooks, M. E., Bruvik, E. M., Duscha, C., Fer, I., Golid, H. M., Hallerstig, M., Hessevik, I., Huang, J., Houghton, L., Jonsson, S., Jonassen, M., Jackson, K., Kvalsund, K., Kolstad, E. W., Konstali, K., Kristiansen, J., Ladkin, R., Lin, P., Macrander, A., Mitchell, A., Olafsson, H., Pacini, A., Payne, C., Palmason, B., Perez-Hernandez, M. D., Peterson, A. K., Petersen, G. N., Pisareva, M. N., Pope, J. O., Seidl, A., Semper, S., Sergeev, D., Skjelsvik, S., Soiland, H., Smith, D., Spall, M. A., Spengler, T., Touzeau, A., Tupper, G., Weng, Y., Williams, K. D., Yang, X., & Zhou, S. The Iceland Greenland Seas Project. Bulletin of the American Meteorological Society, 100(9), (2019): 1795-1817, doi:10.1175/BAMS-D-18-0217.1.

Description: The Iceland Greenland Seas Project (IGP) is a coordinated atmosphere–ocean research program investigating climate processes in the source region of the densest waters of the Atlantic meridional overturning circulation. During February and March 2018, a field campaign was executed over the Iceland and southern Greenland Seas that utilized a range of observing platforms to investigate critical processes in the region, including a research vessel, a research aircraft, moorings, sea gliders, floats, and a meteorological buoy. A remarkable feature of the field campaign was the highly coordinated deployment of the observing platforms, whereby the research vessel and aircraft tracks were planned in concert to allow simultaneous sampling of the atmosphere, the ocean, and their interactions. This joint planning was supported by tailor-made convection-permitting weather forecasts and novel diagnostics from an ensemble prediction system. The scientific aims of the IGP are to characterize the atmospheric forcing and the ocean response of coupled processes; in particular, cold-air outbreaks in the vicinity of the marginal ice zone and their triggering of oceanic heat loss, and the role of freshwater in the generation of dense water masses. The campaign observed the life cycle of a long-lasting cold-air outbreak over the Iceland Sea and the development of a cold-air outbreak over the Greenland Sea. Repeated profiling revealed the immediate impact on the ocean, while a comprehensive hydrographic survey provided a rare picture of these subpolar seas in winter. A joint atmosphere–ocean approach is also being used in the analysis phase, with coupled observational analysis and coordinated numerical modeling activities underway.

Description: The IGP has received funding from the U.S. National Science Foundation: Grant OCE-1558742; the U.K.’s Natural Environment Research Council: AFIS (NE/N009754/1); the Research Council of Norway: MOCN (231647), VENTILATE (229791), SNOWPACE (262710) and FARLAB (245907); and the Bergen Research Foundation (BFS2016REK01). We thank all those involved in the field work associated with the IGP, particularly the officers and crew of the Alliance, and the operations staff of the aircraft campaign.

Description: The dynamics of the boundary layer of the ocean significantly affect the interaction between ocean and atmosphere and, as a result, global climate. The sub-ice boundary layer of the ocean and its dynamics have not been thoroughly studied because of the extremely difficult conditions for observation, in particular during winter. Current understanding of spatial-temporal variability of (sub)mesoscales of the upper Arctic Ocean is extremely limited. At the same time, one of the most important features of the upper ocean layers are the small-scale processes that influence and possibly determine the vertical and horizontal transport of heat, salt, and biologically relevant substances. As a consequence, mathematical models, in particular climate models, experience serious difficulties in parameterization of processes not resolved by the models because of the lack sufficient knowledge to detail the spatial variability at the (sub-)mesoscale. To a better characterization and understanding of (sub)mesoscale dynamics and its role in vertical transport of energy and mass we apply a 3D regional ocean model FESOM-C. The observed vertical hydrological structure and a corresponding reconstructed horizontal temperature and salinity fields were imposed as a part of the forcing for the numerical model. These fields and information about the vertical hydrological structure were utilized by the model as initial conditions and for constraining (nudging) during the spin-up period. After the initial spin-up period, once the model had adjusted to our initial conditions, we performed several free runs. We expect that our 3D numerical studies of eddy properties will contribute to a better characterisation and understanding of (sub)mesoscale dynamics in the Arctic Ocean and its role in the vertical transport of energy and mass.

Description: The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Rabe, B., Heuze, C., Regnery, J., Aksenov, Y., Allerholt, J., Athanase, M., Bai, Y., Basque, C., Bauch, D., Baumann, T. M., Chen, D., Cole, S. T., Craw, L., Davies, A., Damm, E., Dethloff, K., Divine, D., Doglioni, F., Ebert, F., Fang, Y-C., Fer, I., Fong, A. A., Gradinger, R., Granskog, M. A., Graupner, R., Haas, C., He, H., He, Y., Hoppmann, M., Janout, M., Kadko, D., Kanzow, T., Karam, S., Kawaguchi, Y., Koenig, Z., Kong, B., Krishfield, R. A., Krumpen, T., Kuhlmey, D., Kuznetsov, I., Lan, M., Laukert, G., Lei, R., Li, T., Torres-Valdés, S., Lin, L,. Lin, L., Liu, H., Liu, N., Loose, B., Ma, X., MacKay, R., Mallet, M., Mallett, R. D. C., Maslowski, W., Mertens, C., Mohrholz, V., Muilwijk, M., Nicolaus, M., O’Brien, J. K., Perovich, D., Ren, J., Rex, M., Ribeiro, N., Rinke, A., Schaffer, J., Schuffenhauer, I., Schulz, K., Shupe, M. D., Shaw, W., Sokolov, V., Sommerfeld, A., Spreen, G., Stanton, T., Stephens, M., Su, J., Sukhikh, N., Sundfjord, A., Thomisch, K., Tippenhauer, S., Toole, J. M., Vredenborg, M., Walter, M., Wang, H., Wang, L., Wang, Y., Wendisch, M., Zhao, J., Zhou, M., & Zhu, J. Overview of the MOSAiC expedition: physical oceanography. Elementa: Science of the Anthropocene, 10(1), (2022): 1, https://doi.org/10.1525/elementa.2021.00062.

Description: Arctic Ocean properties and processes are highly relevant to the regional and global coupled climate system, yet still scarcely observed, especially in winter. Team OCEAN conducted a full year of physical oceanography observations as part of the Multidisciplinary drifting Observatory for the Study of the Arctic Climate (MOSAiC), a drift with the Arctic sea ice from October 2019 to September 2020. An international team designed and implemented the program to characterize the Arctic Ocean system in unprecedented detail, from the seafloor to the air-sea ice-ocean interface, from sub-mesoscales to pan-Arctic. The oceanographic measurements were coordinated with the other teams to explore the ocean physics and linkages to the climate and ecosystem. This paper introduces the major components of the physical oceanography program and complements the other team overviews of the MOSAiC observational program. Team OCEAN’s sampling strategy was designed around hydrographic ship-, ice- and autonomous platform-based measurements to improve the understanding of regional circulation and mixing processes. Measurements were carried out both routinely, with a regular schedule, and in response to storms or opening leads. Here we present along-drift time series of hydrographic properties, allowing insights into the seasonal and regional evolution of the water column from winter in the Laptev Sea to early summer in Fram Strait: freshening of the surface, deepening of the mixed layer, increase in temperature and salinity of the Atlantic Water. We also highlight the presence of Canada Basin deep water intrusions and a surface meltwater layer in leads. MOSAiC most likely was the most comprehensive program ever conducted over the ice-covered Arctic Ocean. While data analysis and interpretation are ongoing, the acquired datasets will support a wide range of physical oceanography and multi-disciplinary research. They will provide a significant foundation for assessing and advancing modeling capabilities in the Arctic Ocean.

Description: The following projects and funding agencies contributed to this work: Why is the deep Arctic Ocean Warming is funded by the Swedish Research Council, project number 2018-03859, and berth fees for this project were covered by the Swedish Polar Research Secretariat; The Changing Arctic Ocean (CAO) program, jointly funded by the United Kingdom Research and Innovation (UKRI) Natural Environment Research Council (NERC) and the Bundesministerium für Bildung und Forschung (BMBF), in particular, the CAO projects Advective Pathways of nutrients and key Ecological substances in the ARctic (APEAR) grants NE/R012865/1, NE/R012865/2, and #03V01461, and the project Primary productivity driven by Escalating Arctic NUTrient fluxeS grant #03F0804A; The Research Council of Norway (AROMA, grant no 294396; HAVOC, grant no 280292; and CAATEX, grant no 280531); Collaborative Research: Thermodynamics and Dynamic Drivers of the Arctic Sea Ice Mass Budget at Multidisciplinary drifting Observatory for the Study of the Arctic Climate; National Science Foundation (NSF) projects 1723400, Stanton; OPP-1724551, Shupe; The Helmholtz society strategic investment Frontiers in Arctic Marine monitoring (FRAM); Deutsche Forschungsgemeinschaft (German Research Foundation) through the Transregional Collaborative Research Centre TRR 172 “ArctiC Amplification: Climate Relevant Atmospheric and SurfaCe Processes, and Feedback Mechanisms (AC)3” (grant 268020496); The Japan Society for the Promotion of Science (grant numbers JP18H03745, JP18KK0292, and JP17KK0083) and the COLE grant of U. Tokyo; National Key Research and Development Plan Sub-Project of Ministry of Science and Technology of China (2016YFA0601804), “Simulation, Prediction and Regional Climate Response of Global Warming Hiatus”, 2016/07-2021/06; National Science Foundation grant number OPP-1756100 which funded two of the Ice-Tethered Profilers and all the Ice-Tethered Profiler deployments; Chinese Polar Environmental Comprehensive Investigation and Assessment Programs, funded by the Chinese Arctic and Antarctic Administration; Marine Science and Technology Fund of Shandong Province for Qingdao National Laboratory for Marine Science and Technology (Grant: 2018SDKJ0104-1) and Chinese Natural Science Foundation (Grant: 41941012); UK NERC Long-term Science Multiple Centre National Capability Programme “North Atlantic Climate System Integrated Study (ACSIS)”, grant NE/N018044/1; The London NERC Doctoral Training Partnership grant (NE/L002485/1) which funded RDCM; NSF grant number OPP-1753423, which funded the 7Be tracer –measurements; and The Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung (AWI) through its projects: AWI_OCEAN, AWI_ROV, AWI_ICE, AWI_SNOW, AWI_ECO, AWI_ATMO, and AWI_BGC.