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Spatial Coherence of Tropical Rainfall at the Regional Scale

Vincent Moron; Andrew W. Robertson; M. Neil Ward; Pierre Camberlin

Title:
Spatial Coherence of Tropical Rainfall at the Regional Scale
Author(s):
Moron, Vincent
Robertson, Andrew W.
Ward, M. Neil
Camberlin, Pierre
Date:
Type:
Articles
Department:
International Research Institute for Climate and Society
Volume:
20
Permanent URL:
Book/Journal Title:
Journal of Climate
Abstract:
This study examines the spatial coherence characteristics of daily station observations of rainfall in five tropical regions during the principal rainfall season(s): the Brazilian Nordeste, Senegal, Kenya, northwestern India, and northern Queensland. The rainfall networks include between 9 and 81 stations, and 29–70 seasons of observations. Seasonal-mean rainfall totals are decomposed in terms of daily rainfall frequency (i.e., the number of wet days) and mean intensity (i.e., the mean rainfall amount on wet days). Despite the diverse spatiotemporal sampling, orography, and land cover between regions, three general results emerge. 1) Interannual anomalies of rainfall frequency are usually the most spatially coherent variable, generally followed closely by the seasonal amount, with the daily mean intensity in a distant third place. In some cases, such as northwestern India, which is characterized by large daily rainfall amounts, the frequency of occurrence is much more coherent than the seasonal amount. 2) On daily time scales, the interstation correlations between amounts on wet days always fall to insignificant values beyond a distance of about 100 km. The spatial scale of daily rainfall occurrence is larger and more variable among the networks. 3) The regional-scale signal of the seasonal amount is primarily related to a systematic spatially coherent modulation of the frequency of occurrence.
Subject(s):
Meteorology
Publisher DOI:
http://dx.doi.org/10.1175/2007JCLI1623.1
Item views:
65
Metadata:
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