Spatiotemporal variations of temperature and precipitation in Northwest China across multiple timescales

In this study, we investigate the spatiotemporal variation patterns of temperature and precipitation in Northwest China. A 1-km resolution monthly gridded dataset spanning 1960—2023 was employed. Various methods, including linear regression, Theil-Sen median trend estimator, Mann-Kendall test, and Morlet wavelet transform, were used to quantitatively analyze the spatiotemporal characteristics. The results indicate the following. (1) Over the past 64 years, the annual mean temperature and precipitation in the region increased markedly, at rates of 0.28 ℃·(10a)-1 and 3.46 mm·(10a)-1, respectively. Seasonally, the most pronounced warming occurred in spring and the most notable increase in precipitation was observed in summer. (2) Spatially, areas exhibiting a highly pronounced increasing trend accounted for over 94% of the total region for annual and seasonal temperatures. Precipitation generally increased, but statistically significant trends were limited—only 34.96% annually, highest in winter (35.59%). (3) Wavelet analysis revealed multi-timescale periodic oscillations, with the first principal periods for annual temperature and precipitation being 10-16 a and 33-47 a, respectively. These findings provide a scientific basis for addressing climate change and supporting ecological security and sustainable development in Northwest China.