Patrick Minnis — NASA - Langley Research Center
J Kirk Ayers — NASA - Langley Research Cntr/Science Systems and Application
Fu-Lung Chang — Science Systems and Applications, Inc.
Patrick W. Heck — University of Wisconsin
Douglas A. Spangenberg — Science Systems and Applications, Inc.
Paul Lawson — SPEC, Inc.
Rabindra Palikonda — Science Systems and Applications. Inc./NASA - LRC
Szedung Sun-Mack — SAIC, Inc.
Christopher Rogers Yost — Science Systems and Applications, Inc.
Category
Cloud Properties
Description
Time series of (a) cloud boundaries and Learjet altitude, (b) cloud optical depth, (c) effective particle size, and (d) ice water content on 19 January 2010.
Quantifying the microphysical properties of cirrus clouds in global climate models is a difficult but necessary task in order to determine whether they have a net warming or cooling effect on the present and future climate. The amount of shortwave radiation reflected back to space and the longwave radiation emitted back to Earth by cirrus is determined by the size, shape, and concentration of the ice particles composing the cloud. During the Small Particles in Cirrus (SPARTICUS) field campaign, which took place between January and June 2010, the SPEC Learjet 25 was outfitted with several instruments designed to measure such cloud properties. The Geostationary Operational Environmental Satellites (GOES) provided a broad and concurrent view of the large-scale cloud conditions throughout the field experiment, and cloud properties such as cloud-top altitude, optical depth, and effective particle size were routinely derived from these measurements. Similar retrievals were performed using Moderate Resolution Imaging Spectroradiometer (MODIS) data on Terra and Aqua, except that effective particle size is derived from four different wavelengths corresponding to different depths in the cloud. In situ measurements of the cloud particle number concentration are integrated over the size distribution to obtain an effective particle size, a quantity that can also be retrieved from satellite observations. Estimates of ice water content (IWC), which were measured in situ by the 2D-Stereo Probe, are also obtained remotely by simultaneous GOES and some MODIS measurements. Mean profiles of particle size and ice water content are obtained by taking advantage of the Learjet’s ability to take measurements at different altitudes within the cirrus. This study evaluates the small-scale in situ cloud properties and the large-scale satellite-derived properties and documents to what extent the two data sets can be compared.
