Wednesday, 25 January 2012: 11:45 AM
The Famine Early Warning System African Rainfall Climatology Version 2
Room 257 (New Orleans Convention Center )
This paper describes the development of gridded, daily 28-year precipitation climatology dataset centered over the African continent from 40°S to 40° and -20°W to 55°E at a 0.1° spatial resolution. Called the Africa Rainfall Climatology (ARC), historical precipitation estimates are based on inputs from two sources: 1) three-hourly geostationary IR data centered over Africa from Eumetsat, and 2) quality controlled GTS gauge observations reporting 24-hour rainfall accumulations over the Africa continent. Using the methods of the operational RFE algorithm developed by CPC/NOAA for climate monitoring over Africa, both satellite and in-situ rain gauge data are combined to reconstruct a daily precipitation record extending back to 1983, with daily precipitation estimates also available in near real time. Discussion on the acquisition and calibration of historical IR and gauge inputs, algorithm methodology, and final results of the reconstructed ARC are presented. Spatial and temporal comparisons between the reconstructed ARC and other published climatological precipitation datasets, and a validation with independent gauge data in the Gulf of Guinea region of Africa is also presented. Overall, the spatial distribution of mean rainfall and inter-annual variability of rainfall observed in reconstructed ARC dataset illustrate reasonable agreement with the other long-term precipitation datasets, with the exception of a marginal dry bias that regularly occurs during the summer over West Africa. This paper will show that this dry bias is attributed to the lack of daily GTS gauge observations reporting within the region.