HR: 08:15h
AN: A41E-02    [Abstracts]
TI: Study of Global Cirrus Cloud Seasonal Distributions Using CALIPSO Data
AU: * McCormick, M P
EM: pat.mccormick@ hamptonu.edu
AF: Hampton University, 23 Tyler Street, Hampton, VA 23668, United States
AU: Nazaryan, H
EM: hovakim.nazaryan@hamptonu.edu
AF: Hampton University, 23 Tyler Street, Hampton, VA 23668, United States
AU: Tao, Z
EM: zongming.tao@hamptonu.edu
AF: Hampton University, 23 Tyler Street, Hampton, VA 23668, United States
AB: We study the global and seasonal distribution of cirrus clouds using the measurements made by the Cloud- Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite mission. In addition, we present local ground-based lidar validation measurements during CALIPSO overpasses of Hampton University. Few satellite instruments can deduce the presence of cirrus clouds, especially subvisual clouds and those of low optical thickness. Cirrus clouds play a significant role in the energy budget of the earth atmosphere system by means of their effects on the transfer of radiant energy through the atmosphere. Satellite lidar has the ability to profile multi-layer cloud structures and it is particularly useful for the detection of subvisual cirrus. We investigate the latitude-longitude and vertical distributions of occurrence frequency and thickness of cirrus clouds measured by CALIPSO. The investigation of top-layer cirrus clouds shows maximum occurrence frequency of up to 70% near the tropics over the 100° - 180° E longitude band. The average thickness of cirrus clouds is generally between 1.5 and 1.9 km in the majority of latitude-longitude bins. We also analyze the seasonal behavior of the cirrus cloud frequency and geometric thickness. The results show large latitudinal movement of cirrus cloud cover with the changing seasons. The examination of the vertical distribution of cirrus clouds shows the maximum of cirrus top altitude occurrence frequency of ~13% at 16 km in the tropics. The maximum of cirrus cloud base altitude frequency in the tropics is about 10% at 13 km. Cirrus clouds with thickness of ~1 km have the highest occurrence frequency of approximately 15% in the 20° S - 20° N latitude band.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0320 Cloud physics and chemistry
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting