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Statistical indices of the northward rainfall progression over eastern Africa
Author(s) -
Riddle Emily E.,
Wilks Daniel S.
Publication year - 2013
Publication title -
international journal of climatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.58
H-Index - 166
eISSN - 1097-0088
pISSN - 0899-8418
DOI - 10.1002/joc.3429
Subject(s) - climatology , predictability , principal component analysis , environmental science , latitude , index (typography) , range (aeronautics) , geography , geology , statistics , mathematics , geodesy , world wide web , computer science , materials science , composite material
Two statistical indices are developed to represent the northward progression of rainfall between late January and late July over eastern Africa. The first, a Seasonal Location Index, extracts the seasonal phase associated with a daily rainfall map using a principal component analysis. The second, a Rainfall Cluster Index, describes the seasonal cycle as a progression through a series of rainfall patterns that have been defined using a cluster analysis. The indices are used to identify large seasonal shifts in the latitude of rainfall, to examine when these shifts occur, and to investigate circulation features associated with perturbations ahead of and behind the mean seasonal cycle. These indices are potentially useful for exploring the predictability of rainfall transitions at both short‐range and seasonal timescales. Copyright © 2012 Royal Meteorological Society