HR: 1340h
AN: A13C-0947    [Abstracts]
TI: Comparison of In situ Measurements of Cirrus Cloud Ice Water Content during the MidCiX Field Campaign
AU: * Davis, S M
EM: seand@colorado.edu
AF: Laboratory for Atmospheric and Space Physics, University of Colorado 1234 Innovation Drive, Boulder, CO 80303 United States
AU: Avallone, L M
EM: linnea.avallone@lasp.colorado.edu
AF: Laboratory for Atmospheric and Space Physics, University of Colorado 1234 Innovation Drive, Boulder, CO 80303 United States
AU: Hallar, A G
EM: ahallar@mail.arc.nasa.gov
AF: NASA Ames Research Center, Mail Stop 245-4, Moffett Field, CA 94035 United States
AU: Engblom, W
EM: william.engblom@erau.edu
AF: Embry-Riddle Aeronautical University, 600 S. Clyde Morris Blvd., Daytona Beach, FL 32114 United States
AB: Accurate in situ measurements of microphysical properties such as ice water content (IWC, mg m^-3) are important for understanding the role of cirrus clouds in radiative forcing, stratosphere-troposphere exchange, and heterogeneous activation of chlorine and nitrogen compounds. These observations are an important tool for both constraining GCM parameterizations related to the radiative properties of cirrus clouds as well as for providing ``ground-truth'' for satellite retrievals of cloud properties. We present observations of cirrus cloud IWC derived from measurements of ``total water'' made by the University of Colorado closed-path tunable diode laser hygrometer (CLH), which has flown aboard the NASA WB-57 aircraft during several recent field missions, including the Mid-latitude Cirrus Experiment (MidCiX) in April and May, 2004. The CLH measures water vapor resulting from the evaporation of cloud particles after sampling through a heated, sub-isokinetic inlet. When the particle enhancement properties of the inlet system are known and an accurate water vapor measurement is available, the CLH "total water" measurement can be used to derive cirrus cloud IWC for particles between about 5 μm and 500 μm in diameter. Two other instruments with different sampling characteristics reported IWC observations during the MidCiX campaign. We compare the three bulk IWC measurements taken during MidCiX in an attempt to understand systematic differences between the instruments that may arise from sampling characteristics related to particle size. We also present preliminary comparisons of in situ IWC and remotely sensed cirrus microphysical properties from the Terra/Aqua MODIS instruments, and discuss some of the contributions that in situ IWC measurements may make to IWC retrievals from satellite and ground-based platforms.
DE: 0320 Cloud physics and chemistry
DE: 0321 Cloud/radiation interaction
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005