Rainfall Comparison from Different Precipitation Estimates over West Africa
- 1 Department of Meteorology and Climate Science, Federal University of Technology, Akure, Nigeria
- 2 Department of Meteorology and Climate Science, Federal University of Technology, Akure, Nigeria
- 3 Nigerian Meteorological Agency (NIMET), Abuja, Nigeria
Abstract
Comparison of different instantaneous precipitation estimates over three climatic zones in West Africa was carried out using Tropical Rainfall Measurement Mission (TRMM), 3A12 and 3A25 algorithms, the 3B43 rainfall product, and rain gauge product from the Global Precipitation Climatology Center (GPCC) as ground truth. The 3A12 rainfall product is observed to over-estimate rainfall intensity during MAM and JJAS periods, in all the zones, except in Guinea where it is observed to under-estimate rainfall intensity during the JJAS season. It was also observed that Savannah and Sahel had substantial frequency (occurrences) of zero (0 mm/hr) rainfall intensities during MAM, but only the Sahel zone indicated high frequencies of 0 mm/hr rainfall intensities during JJAS. The mean 3A12 rainfall indicated substantial disparity with that of the gauge (GPCC) rainfall especially in Guinea and Savannah. During peak rainfall season (JJAS) all the rainfall products under-estimate rainfall in Guinea and Sahel region of West Africa, but over-estimates rainfall in the Savannah region, whereas during low rainfall episodes (MAM), all the rainfall products over estimate rainfall when compared with the gauge (GPCC) rainfall product. The Gauge (GPCC)-3B43 had the best relationship (highest correlation) in all the three zones during MAM. All the rainfall products showed very strong correlation with Gauge (GPCC) in all the zones in West Africa during the March-May (MAM) period. The Gauge (GPCC)-3B43 correlation maintained the best relationship with Gauge (GPCC) among the rainfall products, during JJAS.
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