Precipitation over Madagascar: Assessment of observed datasets and CMIP6 HighResMIP models for further analysis of drought and its impact on vegetation

Understanding historical evolution and future projections of drought are crucial for Madagascar, which experiences drought almost every year. Not only it contributes to the economic development of the area but it also helps to mitigate direct and indirect impacts of drought on human’s lives and natural ecosystems. To begin with, it is crucial to use accurate datasets for assessing drought in order to get reliable findings. However, Madagascar lacks reliable station datasets. Here, we present the first evaluation of performance of available observed precipitation datasets over the country: gridded precipitation datasets from gauge-based, reanalysis and satellite estimates. Among the 15 analyzed datasets, CHIRPS (Climate Hazards Group Infrared Precipitation with Station data version 2) and ERA5 (European Centre for Medium-Range Weather Forecasts reanalysis fifth generation- Land dataset) the lowest biases compared to the rest. Thus, they are used as the reference for evaluating the performance of CMIP6 HighResMIP simulations. The assessment employs diverse methods, accompanied by the use of the Taylor skill score for ranking the overall performance of the models. The results show that EC-Earth3P-HR, ECMWF-IFS-HR, ECMWF-IFS-LR and HadGEM3-GC31-MM perform the best. The evaluated precipitation datasets are used in current ongoing research of recent drought evolution and its impact on vegetation over Madagascar. Preliminarily results show that the SPI (Standard Precipitation Index) exhibit decreasing trend for all chosen SPI scales (SPI3, SPI6 and SPI12). This indicates that the occurrence of drought over Madagascar has amplified within the study period of 1981 to 2022. Eventually, the evaluation of future projections of drought over the Island would be the next goal to be tackled in order to provide bases for planning appropriate measures in lessening the impact of drought, building effective adaptation strategies and structuring climate change policies.