Performance assessment of multiple precipitation and temperature products for hydro- climatic applications over Pakistan

Abstract

Abstract Due to limited gauge network, Pakistan presents a challenge for cryosphere, hydrological, and ecological studies. Thus, before using precipitation and temperature products for hydro-climatic applications, they must be properly assessed. This study compared six satellite-based precipitation products (SBPPs), one satellite-based temperature product (SBTP), and three temperature reanalysis products (TRPs) to in-situ gauge data to assess their accuracy using ground gauge-based rainfall measurements for the period (2000–2020). The evaluation investigated point-to-pixel data on daily, monthly, seasonal (winter, spring, summer, and fall), and yearly timescales. All products were assessed using four continuous indices (RMSE, CC, bias, and rBias) and four categorical indices (false alarm ratio, probability of detection, success ratio, and crucial success index). According to the evaluation findings, CHIRPS and IMERG outperformed soil moisture family products in daily spatial-temporal capabilities. In terms of accuracy, ERA5 outperformed other temperature products. Monthly satellite-based temperature and precipitation data and temperature reanalysis products performed better than daily estimates (CC < 0.7 and rBIAS within ± 10). On a seasonal scale, IMERG precipitation estimates and ERA5 temperature estimates agreed well with in-situ gauge estimates. In areas with moderate topography, SM2Rain-GPM and ASCAT performed effectively. The evaluation of temperature reanalysis products on the ground demonstrated higher capabilities than AMSR2 LPRM. In terms of detection probability, the ground validation of IMERG beat other SBPPs, whereas ERA5 fared best among SBT and TRPs. The probability density function (PDF) showed that all satellite-based precipitation products captured light precipitation occurrences (> 2mm/day). In general, MEERA-2 and GEOS-5 FP demonstrated moderate performance in low elevated regions, whereas ERA5 and AMSR2 LPRM demonstrated performance comparable to that of gauge estimations across the entire country. The ground evaluation suggests using IMERG's daily and monthly precipitation estimates and ERA5 monthly temperature estimates for hydroclimatic applications in Pakistan's subtropical climates.