Open AccessThe Predictability of Rainfall over the Greater Horn of Africa. Part II: Prediction of Monthly Rainfall during the Long Rains
Author(s) -
Sharon E. Nicholson
Publication year - 2015
Publication title -
journal of hydrometeorology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.733
H-Index - 123
eISSN - 1525-755X
pISSN - 1525-7541
DOI - 10.1175/jhm-d-14-0138.1
Subject(s) - predictability , climatology , environmental science , boreal , forecast skill , atmospheric circulation , atmospheric sciences , geography , geology , mathematics , statistics , archaeology
Seasonal prediction of the boreal spring rains in the Greater Horn of Africa has been notoriously challenging. Predictability is markedly lower than during the autumnal rainy season. Part I of this article explored predictability at the seasonal scale, using multiple linear regression. However, the three months of the boreal spring season are clearly different climatologically and with respect to the prevailing atmospheric circulation and controls on interannual variability. For that reason, the current study follows up on Part I by examining the predictability of the three months individually. The current study utilizes 1- and 2-month lead times and the results are evaluated via cross validation. This approach provided improved skill for April and May in the equatorial rainfall region, but not for March in this region and not for the region with predominantly summer rainfall. Overall, the best predictors are shown to be atmospheric variables, most often zonal and meridional wind. Sea surface temperatures and sea level pressure provided little predictive skill.