HR: 0830h
AN: SA51A-0490    [PDF]
TI: POAM Measurements of Polar Mesospheric Cloud Particle Sizes
AU: * Shettle, E P
EM: shettle@nrl.navy.mil
AF: Naval Research Laboratory, Code 7227 Remote Sensing Division, Washington, DC 20375-5351 United States
AU: Alfred, J M
EM: alfred@cpi.com
AF: CPI, Suite 210, 8001 Braddock Road, Springfield, VA 22151 United States
AU: Lumpe, J D
EM: lumpe@cpi.com
AF: CPI, Suite 210, 8001 Braddock Road, Springfield, VA 22151 United States
AU: Bevilacqua, R M
EM: bevilacqua@nrl.navy.mil
AF: Naval Research Laboratory, Code 7220 Remote Sensing Division, Washington, DC 20375-5351 United States
AB: The Polar Ozone and Aerosol Measurement (POAM II and III) satellite instruments were designed to measure ozone and other trace species in the stratosphere using solar occultation. However, the POAM instruments have proved to be sensitive enough to measure Polar Mesospheric Clouds (PMC). Because of its orbit nearly all the POAM PMC measurements are in the Southern Hemisphere (SH), where its latitude varies between 63 and 70 degrees south, during the PMC season. POAM measures transmission as function of altitude through the earth's atmospheric limb at 9 wavelengths between 355 nm and 1018 nm. POAM II on the SPOT 3 satellite was operational from October 1993 until November 1996, and POAM III on the SPOT 4 satellite has been operational since April 1998, covering eight PMC seasons in the SH. Because of the better the signal-to-noise characteristics of POAM III compared with POAM II, especially in the UV channel, our analysis of the PMC particle sizes will focus on the POAM III results. The transmission measurements are fit with a simple cloud model which allows us to determine the height of the cloud base and top, and the extinction coefficient. The multi-wavelength extinction measurements have been analyzed to determine the characteristic particle sizes in the PMCs. The modal PMC particle size typically ranges from 20 to 70 nm, with the largest sizes being more typical of those clouds, with the greatest optical thickness. Given our derived values of the particle size and PMC extinction coefficient, we also determine the PMC particle number.
DE: 0320 Cloud physics and chemistry
DE: 0340 Middle atmosphere--composition and chemistry
DE: 0360 Transmission and scattering of radiation
DE: 3360 Remote sensing
SC: SPA - Aeronomy [SA]
MN: 2003 Fall Meeting