Evaluation of TRMM 3B42 V7 Rainfall Product in Morocco

In arid and semi-arid countries, drought monitoring is a difficult issue to deal with, mainly due to the low density of precipitation measurement stations. The present study aims to evaluate the ability of the Tropical Rainfall Monitoring Mission (TRMM) 3B42 (v7) to monitor annual precipitation in Morocco. The accuracy of TRMM data to estimate annual rainfall was evaluated. Annual precipitations derived from 5113 daily TRMM 3B42 V7 data were compared to the corresponding in situ rainfall measurements from 23 rain gauges, between 1998 and 2012. The results showed a general, good linear relationship between TRMM and rain gauges data. When considering annual records, the Pearson correlation coefficient, R2, was equal to 0.73 and the Root Mean Square Error, RMSE, was equal to 159.8 mm/year. The correlation between rain gauge measurements and TRMM rainfall has been clearly improved when working with long-term annual average precipitation. The R2 increased to 0.79 and the RMSE decreased to 115.2 mm.