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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 109, D03111, doi:10.1029/2003JD003756, 2004

Geographical distribution and interseasonal variability of tropical deep convection: UARS MLS observations and analyses

Jonathan H. Jiang

Jet Propulsion Laboratory, California Institute of Technology,
Pasadena, California, USA

Bin Wang

Department of Meteorology, University of Hawaii,
Honolulu, Hawaii, USA

Kenshi Goya

Geophysical Fluid Dynamics Laboratory, Kyushu University,
Hakozaki, Fukuoka, Japan

Klemens Hocke

Max-Planck-Institut fur Aeronomie,
Katlenburg-Lindau, Germany

Stephen D. Eckermann

Middle Atmosphere Dynamics Section, Naval Research Laboratory,
Washington, D.C., USA

Jun Ma

Computational Physics Inc.,
Springfield, Virginia, USA

Dong L. Wu and William G. Read

Jet Propulsion Laboratory, California Institute of Technology,
Pasadena, California, USA

Abstract

[1]   Tropical deep convection and its dynamical effect on the tropopause and stratosphere are investigated using a suite of data from the Upper Atmospheric Research Satellite (UARS) Microwave Limb Sounder (MLS), including upper tropospheric humidity, cloud radiance, and gravity wave measurements. For this purpose, geographical distributions of temperature, water vapor, and cloudiness in the tropical tropopause layer (TTL) are compared with corresponding maps of gravity wave variance in the stratosphere. In addition, ECMWF global wind divergent and velocity potential fields as well as NOAA outgoing longwave radiation and CMAP rainfall data are analyzed to help pinpoint the locations of deep convection. We found that high-altitude clouds near the bottom of TTL (~147 hPa) are usually surrounded by high-humidity air, and their spatial pattern and seasonal variability are closely associated with regions of vigorous summertime deep convection. Upward propagating gravity waves generated from these convection regions are shifted poleward by prevailing stratospheric winds. We estimate that tropical deep convection lifts ~5% of the cloud tops to altitudes above 100 hPa and that most of the extreme deep convection events occur in the Western Pacific and Indian monsoon regions. Low-temperature regions in the TTL are associated with, but often drift away from, the center of deep convection. Regions of water vapor maxima near the bottom of TTL are located directly above the deep convection centers, but this moisture behavior is somewhat reversed at the top of the TTL. The integrated picture derived from this study implies that convective scale motions could be important in affecting short-term dehydration processes in the TTL. Our results also suggest that the spatial organization and temporal development of tropical convective systems will be better monitored with the follow-on Earth Observing System (EOS) Aura satellite instruments and lead to improved understanding of the complex interaction of tropical convection with large-scale dynamic and thermodynamic conditions.

Received 8 May 2003; revised 21 November 2003; accepted 2 December 2003; published 13 February 2004.

Keywords: convective processes, gravity waves, stratosphere-troposphere interaction, tropical meteorology.

Index Terms: 3314 Meteorology and Atmospheric Dynamics: Convective processes; 3362 Meteorology and Atmospheric Dynamics: Stratosphere/troposphere interactions; 3374 Meteorology and Atmospheric Dynamics: Tropical meteorology.

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Citation: Jiang, J. H., B. Wang, K. Goya, K. Hocke, S. D. Eckermann, J. Ma, D. L. Wu, and W. J. Read (2004), Geographical distribution and interseasonal variability of tropical deep convection: UARS MLS observations and analyses, J. Geophys. Res., 109, D03111, 10.1029/2003JD003756.

Copyright 2004 by the American Geophysical Union.