Evaluation Product : Cloud Microbase-kazr Profiles (ka) VAP

Site(s)
GAN SGP

General Description

The KAZR radars have recently replaced the MMCR at ARM sites, and so the new KAZR-based radar products will now serve as input to Microbase. All of the historic Microbase (microbasepi2) data files may still be retrieved from the ARM Archive, however this new KAZR-based Microbase (microbaseka) will temporarily reside in the evaluation area.

The Algorithm remains unchanged from the previous Microbase version (microbasepi2) with the exception that the LWP information collected from the Microwave Radiometer is now checked for data quality utilizing the bit-packed QC from the input VAP.

The continuous baseline microphysical retrieval (MICROBASE) VAP now uses a combination of observations from the Ka-band, zenith pointing radar (KAZR), the ceilometer, the micropulse lidar (MPL), the microwave radiometer (MWR) and a merged thermodynamic profile (MERGED SOUNDING) VAP in order to determine the profiles of liquid/ice water content (L/IWC), liquid/ice cloud particle effective radius (re) and cloud fraction. The L/IWC is determined from the radar reflectivity values in the Active Remote Sensing of Clouds (KAZR-ARSCL) VAP (Clothiaux et al. 2000). For liquid cloud layers (T > 0 C) we use the radar reflectivity - LWC relationship derived by Liao and Sassen (1994). This quantity is vertically integrated to provide a liquid water path (LWP), which is then linearly scaled to match the LWP retrieved from the MWR (MWRRET VAP), whenever the MWR value is smaller. Liquid cloud particle effective radii are computed assuming a log-normal droplet distribution with a width of σ = 0.35 and a mode radius given by the relationship derived by Frisch et al (1995). For ice cloud layers ( T ≤ -16 C), the water content is determined using the Z-IWC relationship from Liu and Illingworth (2000), while the cloud particle effective radius is determined as a function of temperature from the relationship of Ivanova et al. (2001). For the mixed-phase region of the cloud (-16 C ≤ T ≤ 0 C) we assume a linear fractionation of ice/liquid where the ice fraction is equal to -T[C]/16.

This baseline retrieval is calculated every 4 seconds with 597 vertical height levels at a resolution of 30 meters.