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propagation of convective complexes observed by trmm in the eastern tropical atlanticPrecipitation maxima during the West African summer monsoon propagate generally westward in tandem with African easterly waves. A heretofore unreported, repeating pattern of northward drift of precipitation maxima is detected on Tropical Rainfall Measurement Mission (TRMM satellite) time-latitude distributions of daily accumulations over the eastern tropical Atlantic. Corresponding 3-hourly TRMM accumulations show that the northward drifting envelopes of precipitation during August 2006 are often comprised of individual swaths propagating towards the southwest, presumably as mesoscale squall lines. The implied northward drift on the time-latitude distribution is a component of a resultant northwestward movement. The study examines the entire available record of TRMM precipitation observations, 1998-2010, to summarize TRMM maxima propagation over the eastern tropical Atlantic. Meridional displacements of precipitation maxima are most prevalent in June-September 2006, occurring less frequently during other summers. An investigation of geopotential and circulation fields, limited to two case studies, suggests mechanisms to explain some of the observed propagation of TRMM maxima. In one event, northward drift of the precipitation envelope is consistent with the corresponding displacement of the intertropical convergence zone trough, although the southwest propagation of individual mesoscale convection maxima does not correspond to any synoptic feature on reanalysis circulation or reanalysis downscaled by a regional model. One speculation is that southwestward propagation of precipitation maxima could be caused by regeneration of convection at outflow boundaries of mature thunderstorms.
Document ID
20120009209
Document Type
Reprint (Version printed in journal)
Authors
Druyan, Leonard M.
(Columbia Univ. New York, NY, United States)
Fulazeka, Matthew
(Columbia Univ. New York, NY, United States)
Date Acquired
August 25, 2013
Publication Date
January 1, 2012
Subject Category
Meteorology and Climatology
Report/Patent Number
GSFC.JA.6140.2012
Funding Number(s)
CONTRACT_GRANT: NSF AGS-1000874
CONTRACT_GRANT: NNG04GN76A
Distribution Limits
Public
Copyright
Public Use Permitted.

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