Evaluation of the GPM precipitation products over the Khar lake - Khovd river basin, Western Mongolia

Considering the insufficient density of the hydro-meteorological observation network in our country, it is crucial to test, verify, validate, and calibrate high-resolution spatiotemporal data derived from satellite products and numerical models are essential to enhance their accuracy and applicability for regional-scale hydrological and climatic analyses. In this study, we selected the Khar Lake-Khovd River watershed, located in the western region of Mongolia and part of the Central Asian endorheic basin. We analyzed the long-term precipitation records from eight meteorological stations within the watershed and compared them with the Global Precipitation Measurement (GPM) data, which have a daily temporal resolution and a spatial resolution of 0.10° × 0.10°. To assess the relationship between observed and satellite-derived precipitation data, we used correlation coefficients at both spatial and individual observation point scales. The results indicate a strong correlation (r = 0.85) between the watershed-wide average precipitation calculated using the Thiessen polygon method and the GPM-derived average precipitation. This suggests that GPM data provide a reliable estimate of total precipitation over the watershed. Furthermore, a statistical analysis was conducted using precipitation data sampled at 937 points to evaluate the influence of surface elevation on GPM precipitation estimates. The results showed a weak correlation between precipitation and elevation. At individual observation points, the correlation between GPM data and meteorological station records was moderate (r = 0.6), which may be attributed to the 0.10° × 0.10° (approximately 10 km × 10 km) spatial resolution of GPM data. Seasonal analysis of GPM precipitation data reveals a spatially scattered pattern during the warm season, whereas in winter, approximately 70% of the lake and wetland areas receive 5–10 mm of precipitation. This pattern reflects the unique characteristics of atmospheric circulation and regional climate dynamics.