Evaluation of satellite-based air temperature estimates at eight diverse sites in Africa

Abstract

High resolution satellite and reanalysis-based air temperature estimates have huge potential to complement the sparse networks of air temperature measurements from ground stations in Africa, and support vital studies in health, agriculture, diseases, and climate change. The recently released Climate Hazards Center Infrared Temperature with Stations (CHIRTS-daily) dataset provides daily minimum and maximum air temperature estimates on a near-global scale from 1983 to 2016. This study assesses the performance of CHIRTS-daily in comparison with measurements from eight ground stations in diverse locations across Africa from 1983 to 2016 and benchmarked against the ERA5 and ERA5-Land reanalysis in order to understand its potential to provide localised temperature information. CHIRTS-daily maximum temperature exhibits good performance across the sites, measures and time scales. Compared to ERA5 and ERA5-Land, CHIRTS-daily has higher correlation and lower bias of daily, annual mean maximum and annual extreme maximum temperature, often within 1.0° on average. It also exhibits significant trends in annual mean maximum temperature, comparable to those from the station data. CHIRTS-daily minimum temperatures generally has higher correlation, but larger bias than ERA5 and ERA5-Land, at more than 2° at four sites. However, the results indicate that CHIRTS-daily minimum temperature biases may be largely systematic, and therefore could potentially be corrected for. Overall, CHIRTS-daily is highly promising as it outperforms ERA5 and ERA5-Land in many areas, and exhibits good results across a small, but diverse set of sites in Africa. Further studies to understand performance in specific geographic areas and terrains could help support these findings.