Su, Hui and Jiang, Jonathan H. and Gu, Yu and Neelin, J. David and Kahn, Brian H. and Feldman, Daniel and Yung, Yuk L. and Waters, Joe W. and Livesey, Nathaniel J. and Santee, Michelle L. and Read, William G. (2008) Variations of tropical upper tropospheric clouds with sea surface temperature and implications for radiative effects. Journal of Geophysical Research D, 113 . D10211. ISSN 0148-0227 http://resolver.caltech.edu/CaltechAUTHORS:SUHjgrd08
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The variations of tropical upper tropospheric (UT) clouds with sea surface temperature (SST) are analyzed using effective cloud fraction from the Atmospheric Infrared Sounder (AIRS) on Aqua and ice water content (IWC) from the Microwave Limb Sounder (MLS) on Aura. The analyses are limited to UT clouds above 300 hPa. Our analyses do not suggest a negative correlation of tropical-mean UT cloud fraction with the cloud-weighted SST (CWT). Instead, both tropical-mean UT cloud fraction and IWC are found to increase with CWT, although their correlations with CWT are rather weak. The rate of increase of UT cloud fraction with CWT is comparable to that of precipitation, while the UT IWC and ice water path (IWP) increase more strongly with CWT. The radiative effect of UT clouds is investigated, and they are shown to provide a net warming at the top of the atmosphere. An increase of IWP with SST yields an increase of net warming that corresponds to a positive feedback, until the UT IWP exceeds a value about 50% greater than presently observed by MLS. Further increases of the UT IWP would favor the shortwave cooling effect, causing a negative feedback. Sensitivities of UT cloud forcing to the uncertainties in UT CFR and IWC measurements are discussed.
|Additional Information:||©2008. American Geophysical Union. Received 19 November 2007; revised 18 January 2008; accepted 18 February 2008; published 31 May 2008. We thank MLS and AIRS colleagues for data support. Discussions with A. Dessler, Q. Fu, B. Lin, R. S. Lindzen, and R. Rondanelli were helpful. This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. JDN is supported by National Science Foundation Grant ATM-0645200 and NOAA Grant NA05OAR4311134. We thank three anonymous reviewers for helpful comments and suggestions.|
|Subject Keywords:||Clouds, SST, cloud feedback|
|Official Citation:||Su, H., et al. (2008), Variations of tropical upper tropospheric clouds with sea surface temperature and implications for radiative effects, J. Geophys. Res., 113, D10211, doi:10.1029/2007JD009624.|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Archive Administrator|
|Deposited On:||23 Dec 2008 00:02|
|Last Modified:||26 Dec 2012 10:40|
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