Overview of the MOSAiC expedition: Atmosphere
Authors: 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 
Published: February 2022

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 scientific research and provide an important foundation for advancing multiscale modeling capabilities in the Arctic.