Atmos. Chem. Phys. Discuss., 10, 8963-8994, 2010
www.atmos-chem-phys-discuss.net/10/8963/2010/
doi:10.5194/acpd-10-8963-2010
© Author(s) 2010. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
The role of tropical deep convective clouds on temperature, water vapor, and dehydration in the tropical tropopause layer (TTL)
J. H. Chae1,2, D. L. Wu1, W. G. Read1, and S. C. Sherwood3
1Jet propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
2Joint Institute for Regional Earth System Science and Engineering University of California, Los Angeles, Los Angeles, California, USA
3Climate Change Research Centre, University of New South Wales, Sydney, Australia

Abstract. Temperature and water vapor variations due to clouds in the TTL have been investigated using co-located MLS, CALISPO, and CloudSat data. Convective cooling occurs only up to cloud top heights, but there is warming above these heights in the TTL. Water vapor and ozone anomalies above cloud top heights support that the warming anomalies occur due to downward motion. Thicker clouds cause a greater magnitude of the temperature anomalies. Water vapor of the environment below cloud tops can either increase or decrease, depending on the cloud top height. The critical factor, which divides these different water vapor variations below cloud tops, is the relative humidity. Clouds hydrate the environment below 16 km, where the air after mixing between cloud and the environmental air does not reach saturation, but clouds dehydrate above 16 km, due to the supersaturation because of the larger temperature drop and the high initial relative humidity. Water vapor above cloud tops has negative anomalies compared to clear skies and suggests another dehydration mechanism.

Citation: Chae, J. H., Wu, D. L., Read, W. G., and Sherwood, S. C.: The role of tropical deep convective clouds on temperature, water vapor, and dehydration in the tropical tropopause layer (TTL), Atmos. Chem. Phys. Discuss., 10, 8963-8994, doi:10.5194/acpd-10-8963-2010, 2010.
 
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