Thermal conditions for PMC existence derived from Odin/OSIRIS and TIMED/SABER data

摘要

We study a relationship between Polar Mesospheric Cloud (PMC) brightness and coincident mesospheric Kinetic Temperatures (KT) measured by two satellite instruments, the Optical Spectrograph and Infrared Imager System and Sounding of the Atmosphere using Broadband Emission Radiometry respectively. Two fifteen-day periods in July 2002 and 2003 have been analyzed. For coincidences <= 3 hours and <= 200 km PMCs with a peak at 82-84 km were observed for the mean KT in this height range <= 142 K. Bright PMCs, at least twice brighter than the seasonal mean, were detected only for KT <= 134 K. The average KT for PMCs at 80 degrees-82.2 degrees N was lower than that at 60 degrees-75 degrees N by 5-8 K. The average KT coincident with PMCs was 1.4 to 7.9 K lower than that for non-PMC cases. There was up to 7% of non-PMC detections for the very low KT, <= 130 K. The total random and systematic uncertainty of this analysis was 9 K.