Meteorological and cloud conditions during the Arctic Ocean 2018 expedition

• Main Authors: Vüllers, Jutta, Achtert, Peggy, Brooks, Ian M., Tjernström, Michael, Prytherch, John, Neely III, Ryan
• Format: Text
• Language: English
• Published: 2020
• Subjects: Arctic; Arctic Ocean; Sea ice
• Online Access: https://doi.org/10.5194/acp-2020-219; https://www.atmos-chem-phys-discuss.net/acp-2020-219/

The Arctic Ocean 2018 (AO2018) expedition took place in the central Arctic Ocean in August and September 2018. An extensive suite of instrumentation provided detailed measurements of surface water chemistry and biology, sea ice and ocean physical and biogeochemical properties, surface exchange processes, aerosols, clouds, and the state of the atmosphere. The measurements provide important information on the coupling of the ocean and ice surface to the atmosphere and in particular to clouds. This paper provides: (i) an overview of the synoptic-scale atmospheric conditions and its climatological anomaly to help interpret the process studies and put the detailed observations from AO2018 into a larger context, both spatially and temporally; (ii) a statistical analysis of the thermodynamic and near-surface meteorological conditions, boundary layer, cloud, and fog characteristics; (iii) a comparison of the results to observations from earlier Arctic Ocean expeditions, in particular AOE96, SHEBA, AOE2001, ASCOS, ACSE, and AO2016, to provide an assessment of the representativeness of the measurements. The results show that near-surface conditions were broadly comparable to earlier experiments, however the thermodynamic vertical structure was quite different. An unusually high frequency of well-mixed boundary layers up to about 1 km depth occurred, and only a few cases of the <q>prototypical</q> Arctic summer single-layer stratocumulus deck were observed. Instead, an unexpectedly high amount of multiple cloud layers and mid-level clouds was present throughout the campaign. These differences from previous studies are related to the high frequency of cyclonic activity in the central Arctic in 2018.