Horizontally extensive cirrus clouds in the TTL over the eastern tropical Pacific

Abstract:

Horizontally extensive cirrus clouds in the tropical tropoapuse layer (TTL) over the eastern tropical Pacific during northern winter (December – February) are investigated by using CALIOP data. Cirrus in the TTL plays an important role on the radiation budget of the Earth, and is important ramifications for stratospheric water vapor (chemical/radiative balance in the stratosphere) and the transport process between troposphere and stratosphere. Over the eastern tropical Pacific, the cirrus cloud occurrence in the TTL is normally low because the eastern tropical Pacific is isolated from the deep convective region. However extensive cirrus cloud with a horizontal scale of ~3000 km was found in January 2009 (Taylor et al., 2009). Following Taylor et al. (2009), we investigate the thin cirrus over the eastern tropical Pacific during winters from 2006/2007 to 2012/2013 by using CALIOP data. We found the extensive cirrus clouds (~3000 km >) in January 2009, February 2010, and January 2013, and all three cases were formed by cold temperature anomalies. The anomalies are deeply related to eastward propagating convective systems in the tropics and the penetration of Rossby waves into the tropics.