Commercial microwave link networks for rainfall monitoring in Burkina Faso: First results from a dense network in Ouagadougou

In addition to sensors such as rain gauges, ground-based radars and satellites, data from Commercial Microwave Link (CML) can provide important information on rainfall. A CML data acquisition system (DAQ) has been in place since 2017 as a pilot project with eight CML links in the city of Ouagadougou and has been gradually expanded. During the 2020 monsoon season, the DAQ system with a temporal resolution of one minute has progressively increased from eight CMLs to over 1000 CMLs. Here we present the results of the analysis of rainfall information derived from CMLs in the city of Ouagadougou. Validation is carried out with the only available rain gauge in the city, providing daily data. Our first analysis focuses on more than 15 CMLs that operate in the frequency range between 10 GHz and 13 GHz in the city of Ouagadougou, the capital of Burkina Faso. These CMLs are less than 8 km long and are either horizontally or vertically polarized. We perform a comparison with daily rainfall data for individual CMLs. Our results for the 2020 monsoon period indicate a good performance of the rainfall information derived from the CML data, both for daily comparison and for the rainfall accumulation. The individual Pearson correlation coefficients are 0.8 and higher with low coefficients of variation, showing a very good distribution of the CML-derived rainfall around the reference for the individual CMLs. The accuracy measures of the CML-derived precipitation estimate for the mean absolute error (MAE), root mean square error (RMSE) and the bias of the individual CMLs showing a good agreement between the two sets of rainfall measurements.