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Regional rainfall climatologies derived from Special Sensor Microwave Imager (SSM/I) dataClimatologies of convective precipitation were derived from passive microwave observations from the Special Sensor Microwave Imager using a scattering-based algorithm of Adler et al. Data were aggregated over periods of 3-5 months using data from 4 to 5 years. Data were also stratified by satellite overpass times (primarily 06 00 and 18 00 local time). Four regions (Mexico, Amazonia, western Africa, and the western equatorial Pacific Ocean (TOGA COARE area) were chosen for their meteorological interest and relative paucity of conventional observations. The strong diurnal variation over Mexico and the southern United States was the most striking aspect of the climatologies. Pronounced morning maxima occured offshore, often in concativities in the coastline, the result of the increased convergence caused by the coastline shape. The major feature of the evening rain field was a linear-shaped maximum along the western slope of the Sierra Madre Occidental. Topography exerted a strong control on the rainfall in other areas, particularly near the Nicaragua/Honduras border and in Guatemala, where maxima in excess of 700 mm/month were located adjacent to local maxima in terrain. The correlation between the estimates and monthly gage data over the southern United States was low (0.45), due mainly to poor temporal sampling in any month and an inadequate sampling of the diurnal cycle. Over the Amazon Basin the differences in morning versus evening rainfall were complex, with an alternating series of morning/evening maxima aligned southwest to northeast from the Andes to the northeast Brazilian coast. A real extent of rainfall in Amazonia was slightly higher in the evening, but a maximum in morning precipitation was found on the Amazon River just east of Manaus. Precipitation over the water in the intertropical convergence zone (ITCZ) north of Brazil was more pronounced in the morning, and a pronounced land-/sea-breeze circulation was found along the northeast coast of Brazil. Inter-comparison of four years revealed 1992 to be the driest over Amazonia, with about a 23% decrease in mean rate compared to the 4-year mean estimated rain rate.
Document ID
19950031164
Document Type
Reprint (Version printed in journal)
Authors
Negri, Andrew J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Adler, Robert F. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Nelkin, Eric J. (Science Systems and Applications, Inc. Lanham, MD, United States)
Huffman, George J. (Science Systems and Applications, Inc. Lanham, MD, United States)
Date Acquired
August 16, 2013
Publication Date
July 1, 1994
Publication Information
Publication: American Meteorological Society, Bulletin
Volume: 75
Issue: 7
ISSN: 0003-0007
Subject Category
METEOROLOGY AND CLIMATOLOGY
Distribution Limits
Public
Copyright
Other