Atmos. Chem. Phys. Discuss., 9, 4035-4079, 2009
www.atmos-chem-phys-discuss.net/9/4035/2009/
doi:10.5194/acpd-9-4035-2009
© Author(s) 2009. 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.
A statistical analysis of the influence of deep convection on water vapor variability in the tropical upper troposphere
J. S. Wright1, R. Fu2, and A. J. Heymsfield3
1Department of Applied Physics and Applied Mathematics, Columbia University,\newline New York, NY, USA
2Jackson School of Geosciences, University of Texas, Austin, TX, USA
3National Center for Atmospheric Research, Boulder, CO, USA

Abstract. The factors that control the influence of deep convective detrainment on water vapor in the tropical upper troposphere are examined using observations from multiple satellites in conjunction with a trajectory model. Deep convection is confirmed to act primarily as a moisture source to the upper troposphere, modulated by the ambient relative humidity (RH). Convective detrainment provides strong moistening at low RH and offsets drying due to subsidence across a wide range of RH. Strong day-to-day moistening and drying takes place most frequently in relatively dry transition zones where the frequency of deep convective events is neither very high nor very low. Many of these strong moistening events can be directly attributed to detrainment from recent tropical convection. The temporal and spatial limits of the convective source are estimated to be about 36–48 h and 600–1500 km, respectively, consistent with the lifetimes of detrainment cirrus clouds. Larger amounts of detrained ice and smaller ice particle sizes are both associated with enhanced upper tropospheric moistening.

Citation: Wright, J. S., Fu, R., and Heymsfield, A. J.: A statistical analysis of the influence of deep convection on water vapor variability in the tropical upper troposphere, Atmos. Chem. Phys. Discuss., 9, 4035-4079, doi:10.5194/acpd-9-4035-2009, 2009.
 
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