Evaluating the performance of high-resolution climate simulations over the Central Himalaya and Karakoram

High Mountain Asia (HMA), often referred to as the Third Pole, plays a critical role in the global water cycle, as it contains the largest reserves of freshwater outside polar regions and provides water supplies to the millions of people downstream. An accurate representation of the hydroclimatic conditions in HMA, especially in the high elevations, is crucial because of the complexity of precipitation and temperature variations and limited observations above 3000 m elevation. This study uses the Weather Research and Forecasting (WRF) model to conduct high-resolution (12-km and 4-km) simulations for the hydrologic years 2016-2018 over the Central Himalaya and Karakoram, areas known for their contrasting glacial environments. The simulations are evaluated using observational data from weather stations above 3000 m elevation and multiple gridded products. WRF reasonably captures the spatial and temporal variability of precipitation and temperature during the monsoon and winter periods for the Central Himalaya and Karakoram, respectively. Compared with the gridded products, WRF overestimates windward precipitation and underestimates leeward precipitation in the Central Himalaya, and overestimates winter precipitation in large areas of Karakoram. Evaluations using weather stations and multiple performance metrics (including coefficient of determination, root mean square error, probability density function, and quantile comparison) suggest that WRF outperforms ERA5-Land, providing an improved representation of hydroclimatic variability over the two focused regions. The comparison between the WRF simulations at 12-km and 4-km resolutions shows that their performance in simulating precipitation in the Central Himalaya is comparable and depends on the reference data used, while the 12-km simulation shows an overall better agreement with both gridded products in Karakoram. For temperature, the 4-km simulation outperforms the 12-km simulation only in Karakoram. This study highlights the regional variability in WRF performance across HMA, emphasizing the need for optimized high-resolution modeling and improved observational networks to reduce uncertainties in complex high-elevation terrains.