Evaluation of GPM-IMERG and TRMM-3B42 precipitation products over Pakistan

Understanding the performance of remotely-sensed precipitation with rain gauge as reference is essential before their application in estimating multiple processes. In current study, Global Precipitation Measurements from Integrated Multi-satellite Retrievals (GPM-IMERG) and Tropical Rainfall Measuring Mission (TRMM-3B42) products were evaluated, taking data a for period 2004 to 2018 over Pakistan. The at daily, monthly, annual seasonal timescales evaluated using statistical (three continuous four categorical) error metrics. Satellite Products (SPPs) showed consistent climatology some regional differences. All SPPs overall performed well central southern regions compared northern region study area. Evaluation revealed that was influenced by topography, while characteristics dependent on intensity climatic condition region. able capture extreme events (95th percentile) across different regions. highest values probability detection (POD), critical success index (CSI), accuracy (ACC) rate 0.7, 0.4, 0.9 observed respectively, lowest value false alarm ratio (FAR) 0.4. IMERG final run harmonizes gauges very closely plain medium elevation regions, root mean square difference greater than 20 mm/month high altitude. spatial distribution correlation coefficients 0.7 suggest selected captured seasonality mutual comparison shows well, followed TRMM-3B42, whereas winter pre-monsoon, early late higher northeast results can help researchers select reliable an alternate source country other adjoining evaluation information algorithm developers rectify errors improve SPPs. • This evaluates GPM-IMERG TRMM-3B42 terrains FAR, POD, CSI, ACC better areas average rainfall. IMERG-F