Millimeter cloud radar observations of mixed-phase clouds – The Doppler spectra story of a riming case study observed in Finland

 
Poster PDF

Authors

Pavlos Kollias — Stony Brook University
Stefan Kneifel — University of Cologne
Heike Kalesse-Los — University of Leipzig
Wanda Szyrmer — McGill University - Dept. of Atmospheric and Oceanic Science

Category

Ice Nucleation and Cloud Phase

Description

Cloud radar Doppler spectra offer a wealth of information about cloud processes. By looking at the evolution of the radar Doppler spectra from cloud-top to cloud-base in a liquid-topped mixed-phase cloud through which ice and snow from an upper level cloud are falling, we try to tell the microphysical evolution story of the hydrometeor populations that are present by disentangling the contributions of the solid and liquid particles to the total radar returns. Instead of considering vertical profiles, dynamical effects are taken into account by following the particle population evolution along slanted tracks which are caused by horizontal advection of the cloud. In the super-cooled liquid layer at the top of the mixed-phase cloud, the identified liquid droplets are used as air motion tracer to correct the Doppler spectrum for vertical air motion. The methodology is demonstrated using vertically pointing cloud Doppler radar measurements from the deployment of the Department of Energy (DOE) Atmospheric Radiation Measurement Program’s (ARM) mobile site AMF2 during the BAECC (Biogenic Aerosols – Effects on Clouds and Climate Snowfall Experiment) in Finland 2014. For the Feb 21, 2014 case study, the liquid water path conditions were favorable for riming to occur on the ice particles from the upper level cloud falling through the supercooled liquid layer. Besides an overview of the profiles of radar moments of the different hydrometeor populations, we will show first results of model simulations including riming using a 1D microphysical bin model. The final goal of this study is to constrain microphysical parameterizations about riming rates.