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Understanding Ice Supersaturation, Particle Growth, and Number Concentration in Cirrus CloudsMany factors control the ice supersaturation and microphysical properties in cirrus clouds. We explore the effects of dynamic forcing, ice nucleation mechanisms, and ice crystal growth rate on the evolution and distribution of water vapor and cloud properties in nighttime cirrus clouds using a one-dimensional cloud model with bin microphysics and remote sensing measurements obtained at the Department of Energy's Atmospheric Radiation Measurement (ARM) Climate Research Facility located near Lamont, OK. We forced the model using both large-scale vertical ascent and, for the first time, mean mesoscale velocity derived from radar Doppler velocity measurements. Both heterogeneous and homogeneous nucleation processes are explored, where a classical theory heterogeneous scheme is compared with empirical representations. We evaluated model simulations by examining both bulk cloud properties and distributions of measured radar reflectivity, lidar extinction, and water vapor profiles, as well as retrieved cloud microphysical properties. Our results suggest that mesoscale variability is the primary mechanism needed to reproduce observed quantities. Model sensitivity to the ice growth rate is also investigated. The most realistic simulations as compared with observations are forced using mesoscale waves, include fast ice crystal growth, and initiate ice by either homogeneous or heterogeneous nucleation. Simulated ice crystal number concentrations (tens to hundreds particles per liter) are typically two orders of magnitude smaller than previously published results based on aircraft measurements in cirrus clouds, although higher concentrations are possible in isolated pockets within the nucleation zone.
Document ID
20090035004
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Comstock, Jennifer M.
(Pacific Northwest National Lab. Richland, WA, United States)
Lin, Ruei-Fong
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Starr, David O'C.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Yang, Ping
(Texas A&M Univ. College Station, TX, United States)
Date Acquired
August 24, 2013
Publication Date
December 1, 2008
Publication Information
Publication: Journal of Geophysical Research - Atmospheres
Publisher: American Geophysical Union
Volume: 113
ISSN: 0148-0227
Subject Category
Meteorology And Climatology
Distribution Limits
Public
Copyright
Other

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