The evaluation of rainfall products over the West African region will be an important component of the Megha-Tropiques (MT) Ground Validation (GV) plan. In this paper, two dense research gauge networks from Benin and Niger, integrated in the MT GV plan, are presented and are used to evaluate several currently available global or regional satellite-based rainfall products.

Satellite estimation of accumulated precipitation is an important facet of the study of the tropical water cycle. An advanced data merging approach using infrared geostationary imagery and microwave constellation based instantaneous rain rate estimates has been implemented in the framework of the Megha‐Tropiques and Global Precipitation Measurements missions. The Tropical Amount of Rainfall with Estimation of ERors (TAPEER) algorithm has been tailored to account for the loss of the MADRAS conical scanning radiometer by using the SAPHIR sounder rainfall detection capability, thanks to a novel two‐constellation implementation of the algorithm. A new bias correction module based on the TRMM PR observations is also presented. The performances of this new version of the product are reviewed with emphasis on West Africa. In particular, using data‐denial experiments, the contribution of SAPHIR data to the rainfall daily accumulation is quantified for various configurations of the microwave constellation and various algorithmic parameter selections. The results show that the daily accumulation statistics are well improved when SAPHIR is taken into the constellation. The improvements can be quantified using bulk statistics but are more evident following a frequency analysis. The pattern of the impact is a complex convolution of rainfall occurrence and of the Megha‐Tropiques mission original sampling. Over the 20°N–20°S belt, in zonal mean, the inclusion of SAPHIR data alters the daily accumulation substantially (more than 50% of the daily accumulation) more than 10% of the time and more than 20% when conditioned upon rainfall. Under both metrics, the improvement is majored in the 12°–17° latitude band where the Megha‐Tropiques mission sampling is at its maximum.

A series of multi‐platform rainfall estimates is evaluated at the daily 1° resolution over three dense rain‐gauge networks in West Africa, in Niger, Burkina Faso and Benin, for the period 2012–2016. The quality of the ground reference, its dependence on the number of gauges and the consequences on the validation are discussed. The primary objective of this work is the evaluation of the newly released Tropical Analysis of Precipitation with an Estimation of Errors (TAPEER) daily one‐degree rainfall accumulation from the Megha‐Tropiques mission. Several other multi‐platform products, GSMAP, CMORPH, PERSIANN, TMPA and IMERG, are also evaluated over the same area to put TAPEER performance into perspective. For each product only the version that uses solely satellite information (no gauge adjustment) is used. The analysis concentrates on the heart of the rainy season in West Africa, from June to September. TAPEER exhibits good skill over the region, with a high correlation and a good reproduction of the frequency distribution of the rain rates, especially in the Sahelian region – Niger and Burkina Faso – where the biases are close to zero. The bias is stronger (and negative) in Benin. This overall good performance is stable from year to year. The other products exhibit less bias in Benin and more in the Sahel. CMORPH stands out with relatively good correlations, GSMAP slightly less and PERSIANN has a very strong bias in the Sahel. IMERG, analysed over a shorter period, is also promising.