Location
East-West Center, University of Hawai'i at Manoa (Honolulu, Hawai'i)
Start Date
16-10-2012 5:30 PM
End Date
16-10-2012 7:30 PM
Document Type
Poster
Description
Two mechanisms are thought to be primarily responsible for the formation of cirrus in the Tropical Tropopause Layer (TTL): detrainment from deep convective anvils and in situ initiation. By analyzing water vapor measurements from the Aura Microwave Limb Sounder (MLS) and ice water content measurements from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), we identify TTL cirrus that contain too much ice to have been formed in situ—and therefore must be of convective origin. Analyzing 3 years of CALIPSO measurements (2008–2010), we found three maxima in the occurrence of convective cirrus: equatorial Africa, the tropical western Pacific, and South America. Over the entire tropics, we found that convective cirrus occur more frequently during boreal winter-spring and less frequently during boreal summer-fall. The convective fractions of cirrus also increase until the cold-point tropopause is reached in most seasons—implying higher probabilities of cirrus around the tropopause being of convective origin. Averaged over 3 years, we find that at least ~30% of cirrus in the TTL are definitely of convective origin.
Analysis of the TTL cirrus and Their Convective Origin - A Water Perspective
East-West Center, University of Hawai'i at Manoa (Honolulu, Hawai'i)
Two mechanisms are thought to be primarily responsible for the formation of cirrus in the Tropical Tropopause Layer (TTL): detrainment from deep convective anvils and in situ initiation. By analyzing water vapor measurements from the Aura Microwave Limb Sounder (MLS) and ice water content measurements from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), we identify TTL cirrus that contain too much ice to have been formed in situ—and therefore must be of convective origin. Analyzing 3 years of CALIPSO measurements (2008–2010), we found three maxima in the occurrence of convective cirrus: equatorial Africa, the tropical western Pacific, and South America. Over the entire tropics, we found that convective cirrus occur more frequently during boreal winter-spring and less frequently during boreal summer-fall. The convective fractions of cirrus also increase until the cold-point tropopause is reached in most seasons—implying higher probabilities of cirrus around the tropopause being of convective origin. Averaged over 3 years, we find that at least ~30% of cirrus in the TTL are definitely of convective origin.
