HESS Hydrology and Earth System Sciences HESS Hydrol. Earth Syst. Sci. 1607-7938 Copernicus Publications Göttingen, Germany 10.5194/hess-18-1625-2014 Comparison of drought indicators derived from multiple data sets over Africa Naumann G. https://orcid.org/0000-0002-8767-5099 1 Dutra E. https://orcid.org/0000-0002-0643-2643 2 Barbosa P. 1 Pappenberger F. https://orcid.org/0000-0003-1766-2898 2 Wetterhall F. https://orcid.org/0000-0001-5331-9064 2 Vogt J. V. https://orcid.org/0000-0003-2955-9484 1 European Commission, Joint Research Centre, Ispra, Italy European Centre for Medium Range Weather Forecasts, Reading, UK 07 05 2014 18 5 1625 1640 Copyright: © 2014 G. Naumann et al. 2014 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://hess.copernicus.org/articles/18/1625/2014/hess-18-1625-2014.html The full text article is available as a PDF file from https://hess.copernicus.org/articles/18/1625/2014/hess-18-1625-2014.pdf

Drought monitoring is a key component to mitigate impacts of droughts. Lack of reliable and up-to-date precipitation data sets is a common challenge across the globe. This study investigates different data sets and drought indicators on their capability to improve drought monitoring in Africa. The study was performed for four river basins located in different climatic regions (the Oum er-Rbia in Morocco, the Blue Nile in eastern Africa, the Upper Niger in western Africa, and the Limpopo in southeastern Africa) as well as the Greater Horn of Africa. <br><br> The five precipitation data sets compared are the ECMWF ERA-Interim reanalysis, the Tropical Rainfall Measuring Mission satellite monthly rainfall product 3B-43, the Global Precipitation Climatology Centre gridded precipitation data set, the Global Precipitation Climatology Project Global Monthly Merged Precipitation Analyses, and the Climate Prediction Center Merged Analysis of Precipitation. The set of drought indicators used includes the Standardized Precipitation Index, the Standardized Precipitation-Evaporation Index, and Soil Moisture Anomalies. <br><br> A comparison of the annual cycle and monthly precipitation time series shows a good agreement in the timing of the rainy seasons. The main differences between the data sets are in the ability to represent the magnitude of the wet seasons and extremes. Moreover, for the areas affected by drought, all the drought indicators agree on the time of drought onset and recovery although there is disagreement on the extent of the affected area. In regions with limited rain gauge data the estimation of the different drought indicators is characterized by a higher uncertainty. Further comparison suggests that the main source of differences in the computation of the drought indicators is the uncertainty in the precipitation data sets rather than the estimation of the distribution parameters of the drought indicators.

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