Arctic stratus cloud properties deduced from ground-based measurements at DOE ARM NSA site

The Arctic plays a major role in global climate change and has considerable influence on the middle latitude belt. The Arctic affects the global climate directly through interactions between its atmosphere, ice cover, land surface and ocean, and through complex coupled feedbacks. To provide a much needed source of validation data for model results and for improving model parameterizations over the Arctic region, the DOE Atmospheric Radiation Measurement (ARM) program established the high-latitude Cloud and Radiation Testbed (CART) site on the North Slope of Alaska (NSA) in 1997. The ultimate goal of the ARM program is to improve the representation and parameterization of clouds and radiation in the general circulation models (GCMs) so that these models can produce more accurate climate change simulations.

To begin the process of evaluating cloud parameterizations against observed data, we have generated a database of stratus cloud properties, including the 10-day means, standard deviations, and frequency distributions from June 2000 through September 2000 at the ARM NSA site (71.32N, 156.61W) using the surface-based data. The database includes two parts: measurements and retrievals. The former consist of cloud amount, base/top heights and temperatures, LWP, solar transmission, surface albedo, as well as SW, IR, and net cloud forcing at surface. The retrievals include the cloud-droplet effective radius and number concentration, broadband shortwave optical depth, and cloud/TOA albedos. The database provides fundamental statistical information about Arctic stratus cloud properties for evaluating global/climate models and serves as the ground truth for satellite validation.