HR: 0800h
AN: A51D-0821    [Abstracts]
TI: Thinning and Lowering of Tropical Cirrus During 1985--1999: Evidence for a Potential Cloud Negative Feedback Mechanism in Global Climate System
AU: * Wang, P
EM: p.wang@larc.nasa.gov
AF: STC/NASA-LaRC, MS 475, Hampton, VA 23681-2199 United States
AU: Minnis, P
EM: p.minnis@larc.nasa.gov
AF: NASA-LaRC, MS 420, Hanpton, VA 23681-2199 United States
AU: Wong, T
EM: takmeng.wong@larc.nasa.gov
AF: NASA-LaRC, MS 420, Hanpton, VA 23681-2199 United States
AU: Palikonda, R
EM: r.palikonda@larc.nasa.gov
AF: ASMI/NASA-LaRC, MS 936, Hampton, VA 23681-2199 United States
AB: Using data from a single, high vertical resolution (1-km), self-calibrating satellite instrument--the Stratospheric Aerosol and Gas Experiment (SAGE) II, it is shown that the tropical high-altitude cloud layer is lowering during 1985-1999. In addition, the cirrus cloud layer above 12.5 km is thinning during the same period. This observed behavior of the tropical high cloud layer is further substantiated by the high-altitude cloud observations from the Internation Satellite Cloud Climatology Project (ISCCP) and by the 300-mb relative humidity measurements from the National Center for Environment Prediction (NCEP). The high cloud layer thinning and lowering coincides with a period of surface warming and increasing outgoing longwave radiation (OLR) reported recently in the literature. By allowing increased emissions of longwave radiation from top cloud layer to space, the thinning and lowering of the tropical high-altitude cirrus layer constitutes a potential negative cloud feedback mechanism in the global climate system, and is likely to be responsible for the observed increase in OLR in the Tropics during 1985--1999.
DE: 3360 Remote sensing
DE: 3374 Tropical meteorology
DE: 3309 Climatology (1620)
DE: 0320 Cloud physics and chemistry
DE: 0399 General or miscellaneous
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting