Abstract The availability and accuracy of high-resolution spatial and temporal climate data are required for various climate-related analyses, especially in areas with varying topography and climate. The long-term ERA5-Land reanalysis data from the European Centre for Medium-Range Weather Forecast (ECMWF) combines climate model and observation data from around the world into a complete and consistent collection with a spatial resolution of 0.1°. This high-resolution climate data is considered to be a reliable gridded dataset spanning various regions. Due to the scarcity of ground-based data in Indonesia, ERA5-Land is expected as an alternative to represent the climate condition. However, a comprehensive assessment prior to usage should be conducted. This study evaluates the proficiency of ERA5-Land based on observation data from the Climate Hazard Group InfraRed Precipitation with Station data (CHIRPS) to represent the precipitation variability over Indonesia during 1990-2022. Comprehensive investigations on the spatial-temporal dynamics of precipitation are presented. The ERA5-Land precipitation trend shows a similar pattern in annual total accumulated precipitation and precipitation cycle to CHIRPS observations. In areas with monsoon patterns like south Sumatera, Java, southern Kalimantan, Sulawesi, and part of Papua, low bias is observed often during the June-July-August (JJA) dry season, while high bias is observed often during the December-January-February (DJF) and September-October-November (SON). The similar observational trends and acceptable bias of ERA5-Land precipitation data convince the use of the data in simulating precipitation variability in the Indonesian region, which is essential for further climate studies.
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