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Ice Nucleation in Deep ConvectionThe processes controlling production of ice crystals in deep, rapidly ascending convective columns are poorly understood due to the difficulties involved with either modeling or in situ sampling of these violent clouds. A large number of ice crystals are no doubt generated when droplets freeze at about -40 C. However, at higher levels, these crystals are likely depleted due to precipitation and detrainment. As the ice surface area decreases, the relative humidity can increase well above ice saturation, resulting in bursts of ice nucleation. We will present simulations of these processes using a large-eddy simulation model with detailed microphysics. Size bins are included for aerosols, liquid droplets, ice crystals, and mixed-phase (ice/liquid) hydrometers. Microphysical processes simulated include droplet activation, freezing, melting, homogeneous freezing of sulfate aerosols, and heterogeneous ice nucleation. We are focusing on the importance of ice nucleation events in the upper part of the cloud at temperatures below -40 C. We will show that the ultimate evolution of the cloud in this region (and the anvil produced by the convection) is sensitive to these ice nucleation events, and hence to the composition of upper tropospheric aerosols that get entrained into the convective column.
Document ID
20010048416
Acquisition Source
Ames Research Center
Document Type
Conference Paper
Authors
Jensen, Eric
(NASA Ames Research Center Moffett Field, CA United States)
Ackerman, Andrew
(NASA Ames Research Center Moffett Field, CA United States)
Stevens, David
(Lawrence Livermore National Lab. Livermore, CA United States)
Gore, Warren J.
Date Acquired
August 20, 2013
Publication Date
January 1, 2001
Subject Category
Meteorology And Climatology
Meeting Information
Meeting: European Geophysical Society Meeting
Location: Nice
Country: France
Start Date: March 25, 2001
End Date: March 30, 2001
Sponsors: European Geophysical Society
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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