HR: 17:30h
AN: SA14A-07    [Abstracts]
TI: Mesospheric Ice Mass determined from the AIM CIPS imaging experiment
AU: * Thomas, G E
AF: University of Colorado - LASP, 1234 Innovation Drive, Boulder, CO 80303, United States
AU: Rusch, D W
AF: University of Colorado - LASP, 1234 Innovation Drive, Boulder, CO 80303, United States
AU: Merkel, A
AF: University of Colorado - LASP, 1234 Innovation Drive, Boulder, CO 80303, United States
AU: Bailey, S
AF: Bradley Department of Electrical and Computer Engineering, 302 Whittemore Hall Virginia Tech, Blacksburg, VA 24061, United States
AU: Russell, J
AF: Center for Atmospheric Sciences, Hampton University, Hampton, VA 23668, United States
AB: The NASA Aeronomy of Ice in the Mesosphere satellite (AIM) was launched into a sun-synchronous orbit on April 25, 2007. The primary mission of AIM is to determine how Polar Mesospheric Clouds (PMC) are formed and how they evolve. One of the three instruments on board is a panoramic UV camera (the Cloud Imaging and Particle Size or CIPS experiment) designed to measure PMC structures at high (5 km) spatial resolution. The CIPS observing strategy provides images of the same cloud at up to 7 scattering angles. A major objective of AIM is to derive particle sizes and ice content of PMC. Given the PMC brightness at various scattering angles, we employ a method first used by Englert and Stephens to derive the column ice mass. The method uses the approximation of a power-law dependence of the scattering cross-section versus particle size r. The dependence varies from r6 at small scattering angles to r3 at large scattering angles. We call this a "moment method" since the scattered radiance is proportional (with an error up to 25 percent) to a moment of the size distribution. In particular, a measurement at a scattering angle of 115o is approximately a measurement of the third moment of the size distribution, in other words, is directly proportional to the total (columnar) ice particle volume. The method makes no assumptions about the particle radius (except that it is in the range of 30-100 nm), distribution width, or even to particle non-sphericity, as long as the crystals are not too elongated or flattened. We will derive maps of PMC ice mass for selected days, and compare with previous estimates of this important quantity for understanding PMC microphysics.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0340 Middle atmosphere: composition and chemistry
DE: 0394 Instruments and techniques
DE: 3332 Mesospheric dynamics
SC: SPA-Aeronomy [SA]
MN: 2007 Fall Meeting