A common microphysical structure for midlevel mixed phase clouds in the mid-latitudes: Results from the Cloud Layer Experiment (CLEX-9)

Comprehensive measurements of midlevel mixed phase clouds in the mid-latitude region were conducted during the CLEX-9 campaign in western Nebraska from October to November 2001. The experiment was accomplished by employing the University of Wyoming King Air (UWKA) research aircraft equipped with typical in-situ cloud microphysical instruments, such as the PMS-2DC, 2DP, FSSP-100, DMT LMC-100 and Gerber PVM-100A. The campaign flew ten sorties on eight flight days, accumulating more than 16 hours of in-cloud observational data. A common cloud structure observed during the campaign is that the altocumulus cloud is topped by a super-cooled liquid layer with ice particles falling as virga beneath. This finding confirms an earlier speculation that the midlevel mixed phase clouds in the mid-latitude region possess a microphysical structure similar to that recently reported for mixed phase Arctic stratus. In this presentation, we will briefly describe the field campaign and present the observed microphysical structure of these clouds.