Preliminary retrievals of cloud and drizzle properties in the Azores using optimal estimation theory

Description

Advancing our understanding of the cloud-scale physical processes that affect cloud lifetime requires high-resolution measurements in clouds. One area of great interest is the separation of cloud and drizzle microphysics and turbulence in warm clouds to shed light on precipitation initiation, evolution, and the influence of aerosols and dynamics. Here, observations from the 21-month long ARM Mobile Facility (AMF) deployment in the Azores, as part of the Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) field campaign, are used to develop an optimal estimation theory retrieval algorithm that aims to separate cloud and drizzle properties.

The measurement vector includes the W-band radar Doppler spectrum profiles, liquid water path measurements from the microwave radiometer, cloud base height measurements from the ceilometer, and thermodynamics information from the nearest sounding. The output variables include the particle size distributions and liquid water content of drizzle and cloud populations, as well as vertical air motion, eddy dissipation rate, and liquid water flux. Furthermore, the methodology implicitly generates uncertainty estimates for all retrieved variables.

In this presentation, we show preliminary results that extend our recent cloud/drizzle retrieval capabilities from light drizzle to all drizzling conditions through application of the optimal estimation algorithm. A preliminary assessment of retrieval quality is made using the coherency of retrieved fields in time and space and through comparisons of retrieved drizzle parameters at the cloud base with those from the O’Connor radar/lidar technique.