Related Research Areas
Water & Energy Cycles

We propose to make fast-response in situ measurements of cloud ice water content (IWC) using a tunable diode laser hygrometer coupled to a subisokinetic inlet from the NASA WB-57F in support of the Midlatitude Airborne Cirrus Properties Experiment (MACPEX). IWC is a common prognostic variable in modern general circulation models from which cloud effective radius is determined; effective radius is a fundamental parameter used to estimate a cloud's radiative impact. Direct measurements of IWC are critical not only for validation of cloud properties remotely sensed by satellite instruments, but also for improving the treatment of clouds in climate models. The University of Colorado closed-path laser hygrometer (CLH) has flown on several airborne campaigns to provide observations of IWC primarily in cirrus clouds and high altitude rocket exhaust plumes. High temporal resolution data are available from SOLVE, CRYSTAL-FACE, MidCiX, PUMA, TC4 and START08 in a variety of cirrus cloud types. We propose to extend this measurement database with observations of midlatitude cirrus obtained during over the Southern Great Plains ARM site during MACPEX. CLH is a compact, lightweight (less than 35 lbs), power-efficient instrument that provides rapid (2 - 8 Hz) measurements of "total water" with an accuracy of better than 20% (2-sigma). In combination with a simultaneous measurement of water vapor, typically obtained from JPL's JLH or Harvard's HW instrument, ice water content can be calculated. Data analysis activities after MACPEX will focus on quantification of the variability of IWC in different cloud types and the impact of horizontal and vertical variability on the accurate retrieval of cloud properties from remote sensors. We will work with satellite instrument teams, especially the MODIS team, to validate cirrus retrieval algorithms and to assess the importance of the variability of cloud properties on the accuracy of those retrievals.

Project PI: Linnea Avallone/University of Colorado

University of Colorado Campus Box 590 Boulder, CO 80309

Phone: (303) 492-5913



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Started: Sep 27, 2010

Last Activity: Jan 04, 2011


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