The Effect of Spatial Variability on Autoconversion and Accretion rate in Eastern North Atlantic Boundary Layer Clouds

Description

Autoconversion and accretion are the key microphysical processes affecting the boundary layer clouds and precipitation. Recent studies have explored how these processes are represented in models and have stressed the need to consider the scale dependences of these processes. Here we investigate how spatial variability of cloud water and precipitation affects the grid mean autoconversion and accretion rate using data collected at the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program Eastern North Atlantic (ENA) site. Specifically, we have developed a retrieval algorithm by extending retrieval approaches developed by various ASR investigators over the years to simultaneously determine cloud and precipitation water mixing ratio using a combination of the Ka-band ARM zenith radar (KAZR), microwave radiometer and radiosonde observations. The spatial variability of and , and their impacts on grid mean autoconversion and accretion rates will be evaluated as a function of grid size, cloud fraction, precipitation fraction, in cloud mean water content, cloud liquid water path, altitude relative to cloud boundaries, and the cloud vertical depth. Uncertainty in the results will be assessed using a Monte Carlo method.