Surface and cloud coupling in cold air transformation: Lessons from Lake-ICE

During cold air transformation of the sort measured in Lake-ICE, a number of convective processes are enhanced which are not fully understood. These include the coupling of cloud layer fluxes to the subcloud layer and surface, enhancement of larger scale convection in the cloud layer, flux-profile relationships in the cloud layer, and non-local convective plumes. This paper will present results on these issues based upon the intense10 January 1998 Lake-ICE case.

The results will be obtained from two separate sources: cloud resolving model fields [Wisconsin Nonhydrostatic Modeling System (NMS)] and in situ aircraft data [Wyoming King Air]. Diagnoses of each data set will include: (1) scale filtering to identify robust convective structures, (2) conditional sampling to isolate the dominant physical characteristics of the structures, and (3) identification of cloud structure category (eg cumulus, stratocumulus, embedded rolls). These properties will be compared to parameterizations of nonlocal moist convection (eg, Li and Young, 2000) and related simulations.