HR: 1330h
AN: A13A-13    [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: University of Colorado, Laboratory for Atmospheric and Space Physics, 1234 Innovation Dr., Boulder, CO 80303 United States
AU: Avallone, L M
EM: avallone@lasp.colorado.edu
AF: University of Colorado, Laboratory for Atmospheric and Space Physics, 1234 Innovation Dr., Boulder, CO 80303 United States
AB: Accurate in-situ measurements of microphysical properties such as ice water content (IWC, mg/m³) are important for understanding the role or cirrus clouds in radiative forcing, stratosphere-troposphere exchange, and heterogenous activation of chlorine compounds. These observations also provide an important tool for both constraining GCM paramaterizations related to the radiative properties of cirrus clouds as well as "ground-truth" for satellite retrievals of cloud properties. An understanding of the contribution of small particles to IWC is especially relevant because by mass, small particles exert a relatively large influence on the radiative properties of cirrus clouds. 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, subisokinetic inlet. When used in conjunction with knowledge of the particle enhancement properties of the inlet system and an accurate water vapor instrument, the CLH "total water" measurement can be used to derive cirrus cloud IWC for particles between about 5 μm and 500 μm. In addition to the CLH IWC measurement, two other IWC measurements with different sampling characteristics were made during the MidCix campaign. By comparing the three IWC measurements, it is possible to evaluate the contribution of small particles (diameter < 10 μm) to the IWC measurement.
DE: 0320 Cloud physics and chemistry
DE: 3309 Climatology (1620)
SC: Atmospheric Sciences [A]
MN: 2005 Joint Assembly