HR: 0800h
AN: A21E-0779    [Abstracts]
TI: Statistics of Tropospheric and Stratospheric Layers From 1994 to 2007 Over Southwestern Ontario Using Lidar Backscatter Measurements
AU: * Sica, R J
EM: sica@uwo.ca
AF: Department of Physics & Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada
AU: Argall, P S
EM: pargall@uwo.ca
AF: Department of Physics & Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada
AU: Doucet, P J
EM: pdoucet2@uwo.ca
AF: Department of Physics & Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada
AB: The Purple Crow Lidar (PCL) is a laser radar which has been in operation since 1992 from the Delaware Observatory, a University of Western Ontario research facility near London, Canada (42.87°N, 81.38°W, 225m elevation). The PCL has a large power-aperture product due in part to its use of a 2.6m diameter telescope. The PCL was designed for temperature measurements in the stratosphere, mesosphere and lower thermosphere. However, the system also measures total backscatter from near the surface to about 18km altitude. Measurements on 450 nominally "clear" nights have been analyzed to determine the occurrence of tropospheric and stratospheric layering events. Cloud or layers were measured having a top altitude above 7.5km on about 200 of these nights and above 12.5km on 63 nights. Of these events, there are 9 above 7.5km altitude that exhibit features that are consistent with layers, that is they produce a significant increase in the scattering ratio profile, are diffuse and lacking in vertical or temporal structure, are very narrow (less than a few hundred meters) and exist for hours. There are 5 layers that exceed 12.5km altitude and are likely in the stratosphere. Furthermore, 4 of these 5 layers occur over a period of a week in late June and early July, 2002. These layers are probably connected with pyroCb events resulting from intense fires in Manitoba and Saskatchewan. The other stratospheric layer occured on the night of May 5, 2007. We will refine our technique of discriminating between layers and clouds, as well as investigate the relation of these events to fires.
DE: 3311 Clouds and aerosols
DE: 3334 Middle atmosphere dynamics (0341, 0342)
DE: 3362 Stratosphere/troposphere interactions
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting