New Microphysical Insights from Analysis of Centimeter-Resolution Holographic Data during ACE-ENA

 
Poster PDF

Authors

Neel Desai — Brookhaven National Laboratory
Yangang Liu — Brookhaven National Laboratory
Susanne Glienke — Pacific Northwest National Laboratory
Raymond A Shaw — Michigan Technological University

Category

ARM field campaigns – Results from recent ARM field campaigns

Description

HOLODEC (Black tips) attached below an aircraft wing along with a 2DC probe. Image courtesy: NCAR
Understanding cloud microphysics is essential to have accurate parameterizations for weather and global climate models and to improve their accuracy. Airborne in-situ measurements are vital for understanding cloud microphysical properties such as cloud droplet concentration, droplet size distributions and relative dispersion. However, conventional cloud probes suffer from large scale averaging (e.g., 100 m) due to linear sampling limitations. Holographic instruments do not suffer from such a drawback by providing volume measurements at centimeter spatial resolutions. Analyzing such centimeter scale volume measurements and comparing them with conventional measurements gives us new insight into the physical processes such as entrainment-mixing and turbulence-microphysics interactions at play over the scales that have been largely beyond reach. In this study, we analyze airborne digital holographic measurements from the Holographic Detector for Clouds (HOLODEC) during the Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA) campaign. This campaign consisted of ARM Aerial Facility (AAF) Gulfstream-159 (G-1) research aircraft which flew from Terceira Island in the Azores during two intensive operational periods: early summer 2017 (June to July) and winter 2018 (January to February). These research flights and corresponding ground-based measurements sampled Marine Boundary Layer (MBL) clouds to analyze their aerosol and cloud properties. Each hologram from HOLODEC provides a volume measurement of approximately 11 cubic centimeters with droplet local number concentration and size distribution. Variability in droplet size distributions and mixing behavior are analyzed and correlated with local turbulence properties. Cloud properties are found to be scale dependent and vary spatially as well as altitudinally in the clouds. This analysis should give us a better insight on cloud microphysical behavior in MBL clouds