Evaluation and application of satellite rainfall datasets using Google Earth Engine platform in Arunachal Pradesh, Eastern Himalayan Region of India

The blended satellite and ground-based datasets are publicly accessible and valuable for detecting rainfall geographical and temporal variation at a finer resolution. These products have been utilised extensively in weather and climate modelling, hydrology, and agricultural research. However, it’s important to note that the accuracy of these satellite products can vary spatially and across different datasets. Three satellite and one reanalysis gridded rainfall products CHIRPS (Climate Hazards Group InfraRed Precipitation with Station Data Version 2), TRMM (TRMM 3B43: Monthly Precipitation Estimates), TerraClimate (High-resolution global dataset of monthly climate University of Idaho), and ERA-5 (Land monthly Averaged-ECMWF Climate Reanalysis Version 5) were analysed using Google Earth Engine (GEE) and evaluated with station-based observed rainfall data to determine the representative dataset for trend analysis in different agroclimatic zones in Arunachal Pradesh, Northeast India. The trend analysis was conducted based on 20-year long-term precipitation data at an annual and seasonal scale in different agroclimatic regions of Arunachal Pradesh, India. The global performance index (GPI) ranking identified CHIRPS as the most suitable alternative data for station-observed data records. It was then used for the spatial trend analysis of different agroclimatic zones on an annual and seasonal scale at the pixel level in GEE. Several approaches were used to identify trends, including the nonparametric Mann-Kendall test, Sen’s slope estimator, and Z statistics. The patterns derived from grid-based data were compared to observed precipitation data. Seasonally, a significant declining trend was noted for the alpine zone (AZ) and the Temperate sub-alpine zone (TSAZ). Mid-tropical hill zone (MTHZ) and Sub-tropical hill region (STHR) reported a minor decline trend. Overall, in all Arunachal Pradesh agroclimatic zones, the findings indicated a general decreasing trend on an annual and seasonal scale. Observed and satellite rainfall gridded data trend analysis revealed the same pattern with different magnitudes.