The international Arctic Summer-Clouds Ocean Study (ASCOS) will provide an opportunity during the International Polar Year (IPY) to obtain measurements of macro- and microphysical properties of clouds over the pack ice in the high Arctic. These measurements will be particularly unique and valuable because they will be co-located with fine-scale measurements of the Arctic boundary-layer structure and processes and of aerosol concentrations and types. The data set will be a legacy of IPY. In particular, they provide critical data for validation of climate model parameterizations of Arctic clouds, addressing a key issue identified in current climate models.
Funds are provided to:
1) Deploy a cloud radar, a microwave radiometer, and a ceilometer onboard the icebreaker R/V Oden to obtain measurements from which the PI will derive cloud macro- and microphysical properties. The measurements will be obtained in Arctic all-liquid, all-ice, and mixed-phase clouds near the North Pole during the international ASCOS field program in July- September, 2008. The macrophysical properties will include cloud base, cloud top, cloud fraction, cloud duration, and cloud reflectivity. The microphysical properties will include cloud phase, liquid water path, and profiles of ice water content, ice particle effective radius, liquid water content, effective drop radius, vertical velocity, and turbulent dissipation rate.
2) Compare these properties during this pack-ice transition season to cloud properties similarly derived by the project participants and others over the pack ice during SHEBA, at Arctic Ocean coastal sites near Barrow, Alaska, and at the SEARCH site in Eureka, Canada.
3) Temporally and spatially link these cloud properties to the evolution of the boundary-layer wind and thermodynamic structure and to the evolution and distribution of aerosols measured by other researchers during ASCOS. This objective will provide insights to key processes for the current climate and for Arctic climate change, and is highly linked to work by other ASCOS participants, hence requiring significant international scientific collaboration.
