Observations of Dynamics, Thermodynamics and Radiation Associated with Boundary Layer Clouds
Boundary layer clouds cool the Earth by reflecting greater incoming shortwave radiation compared to the underneath surface, while emitting longwave radiation comparable to the underneath surface. As these clouds occur at scales much smaller than the Global Climate Model (GCM) resolution, their effects and the associated processes need to be parameterized in GCM simulations aimed at predicting the future climate. The long-term and detailed observations from the Atmospheric Radiation Measurement (ARM) climate research facilities offer a unique opportunity to study these clouds and characterize the associated dynamic, thermodynamic and radiative processes, furthering our understanding of these clouds and leading to better parameterizations.
Boundary layer clouds are routinely observed at the ARM Southern Great Plains (SGP) facility in Oklahoma and also were routinely observed during the deployment of the ARM Mobile facility (AMF) at the island of Graciosa (GRW) in the Azores. We have used data collected by vertically pointing Doppler cloud radars part of the ARM SGP and AMF GRW instrumentation to characterize the dynamics associated with these clouds. We have also used the data from the cloud radars along with that collected by other instruments and a 1-Dimensional model to characterize the thermodynamic and radiative structure of boundary layer clouds observed at these two ARM sites. Results from these studies will be presented along with those from a case-study which focuses on the interplay between boundary layer turbulence, radiation and thermodynamics.