Entrainment in Stratocumulus

November 15, 2012

Hermann Gerber

Hosted by Jeff Collett

Abstract

We know that stratocumulus clouds (Sc) contribute significantly to the EarthÂ’s radiation budget and thus must be understood for predicting climate change. This talk looks at relatively recent Sc measurements (POST; Physics of Stratocumulus Top) off the California coast that follow multiple other such efforts. The POST field campaign is a direct result of learning from earlier studies including DYCOMS-II. Both DYCOMSII and POST had the same goals: measure entrainment velocity in Sc accurately and use them as a reference for entrainment-velocity parameterization and as Â“ground-truthÂ” for model inter-comparison. POST had the advantage of utilizing improved high-resolution sensors for both in- and out-of cloud measurements, with the ultra-fast temperature probe (UFT) from the University of Warsaw playing a staring role; and with the better co-location of probes on the POST aircraft also contributing. The POST results are compared to Sc modeling results from colleagues associated with the Department including David Randall, Bjorn Stevens, and Tak Yamaguchi. Others results from Margareet VanZanten, Shouping Wang, J. Katzwinkel, and Samantha Hill are also discussed.