Aircraft observations during the 2008 ASCOS/AMISA field program: Overview of the synoptic/mesoscale environment, boundary-layer structure, and cloud microphysics

Arctic clouds and boundary-layer thermodynamic structure are believed to have an important impact on the surface energy budget of the Arctic pack ice, and hence on the fate of the Arctic sea ice. Unfortunately, many of the microphysical and dynamical processes affecting key properties of these clouds and their interaction with the sea ice are unknown. One of the main objectives of joint Arctic Summer Cloud-Ocean Study (ASCOS) and Arctic Mechanisms of Interaction between the Surface and Atmosphere (AMISA) field programs was to provide the data by which our understanding of these processes can be improved. ASCOS/AMISA was conducted in August and September 2008 near the North Pole using two primary platforms, the Swedish ice breaker Oden and the U. S. National Aeronautic and Space Administration (NASA) DC-8 research aircraft.

The NASA DC-8 aircraft flown during AMISA provided in-situ, remote sensing, and dropsonde observations of the macro- and microphysical structure of the Arctic clouds, the associated thermal and kinematic structure of the Arctic boundary layer, and the structure of the ice surface conditions. Airborne remote sensors provided high resolution microwave imagery of sea ice using the Polarimetric Scanning Radiometer (PSR/A) system, potential discrimination of fresh water meltponds using the LRAD L-band radiometer, and direct sampling of thermodynamic and cloud variables over wide areas using in-situ cloud probes, dropsondes, and radiometric profiling. In-situ aircraft measurements included cloud liquid water, cloud and aerosol particle size distributions, and aerosol composition. Additional microphysical and thermodynamic observations will be available through remote-sensing retrieval methods.

The presentation will summarize the data collected from the aircraft, focusing on the synoptic/mesoscale environment and its links to the boundary layer structure and the cloud microphysics. Preliminary analysis of interesting time periods will be shown to illustrate the extent and breadth of the data set. The aircraft data will be supplemented with some data from surface-based remote sensors on the Oden. A brief discussion outlining how these data will be used to address the interdisciplinary objectives of ASCOS and AMISA will be given, focusing on the objectives linked to Arctic clouds