Simulating the precipitation in the data-scarce Tianshan Mountains, Northwest China based on the Earth system data products

摘要

Precipitation in mountains is the main source of water supply and an important hydro-climate variable in the arid regions of Northwest China. However, the precipitation data is scarce here because of rare meteorological stations, which results in the errors of hydrological forecast. Therefore, adopting an effective method to obtain high-precision precipitation data in mountains is a vital problem to be solved. Selecting the Tianshan Mountains in Northwest China as a target, we developed a simulation method based on the Earth system data products to address this issue. To simulate the monthly precipitation, we fitted a nonlinear regression model and rectified it by bilinear interpolation. The effect of our model was verified by the observed precipitation in 24 meteorological stations, and the coefficient of determination (R-2 = 0.71) and Nash-Sutcliffe efficiency coefficient (NSE = 0.71) indicated its good performance. By using the model, we obtained the high-precision and high-resolution precipitation dataset with a spatial resolution of 1 km x 1 km from February 2000 to February 2018 in the Tianshan Mountains. The dataset tells us that the precipitation in the Tianshan Mountains presents a slow upward trend with an increase of 2 mm per year in the past 18 years. The seasonal pattern is that precipitation is more in summer and less in winter. The spatial pattern is that the precipitation in the north slope is more than that in the south slope, and the highest value of annual precipitation with 264 mm distributes in the Middle Tianshan, followed by the West Tianshan with 220 mm and the East Tianshan with 110 mm. We also find that the Arctic Oscillation Index (AOI) in summer and the North Atlantic Oscillation Index (NAOI) in last winter are main indices, which correlate with the increased precipitation in the Tianshan Mountains on the global scale.