河西走廊1961—2020 年极端气候时空 特征及其对NDVI的响应 postprint

Abstract: Global climate change has increased the frequency and intensity of extreme climate events, severely threatening ecosystems in arid and semiarid regions. As an ecologically vulnerable zone in Northwest China, the Hexi Corridor presents an obvious warming and drying trend. Clarifying vegetation responses to extreme climates is therefore essential. Based on meteorological data (1961–2020) and MODIS NDVI datasets (2000–2020), we calculated 27 extreme climate indices using the RClimDex tool. Combined with inverse distance weighting interpolation and correlation analysis, this study explored the spatiotemporal variations of extreme climates and their vegetation responses. The results indicated that: (1) Extreme temperature exhibited an increasing trend. TX90p and TN90p increased by 2.1 d·(10 a)-1 and 3.0 d·(10 a)-1, showing an obvious asymmetric diurnal warming. TXx and TNx rose by 2.8 °C and 2.1 °C, with Jiuquan in the northwest as the high-temperature center. (2) Extreme precipitation displayed increasing amount and intensity. PRCPTOT, RX1day, and RX5day increased by 60.5 mm·(10 a)-1, 0.38 mm·(10 a)-1, and 0.65 mm·(10 a)-1, respectively. Precipitation was concentrated in the southeast due to orographic uplift. (3) Vegetation sensitivity exhibited distinct spatial heterogeneity. Northwestern vegetation was more sensitive to extreme temperature, while central and southwestern vegetation responded strongly to extreme precipitation. NDVI was significantly positively correlated with R95p (r_xy = 0.61), with positive correlation areas exceeding 50%; TXx was negatively correlated with NDVI across the entire study area. This study clarified the spatiotemporal variations of extreme climates and their influencing mechanisms on vegetation in the Hexi Corridor. These findings provide scientific references for ecological vulnerability assessment and climate-vegetation feedback understanding in arid inland basins, supporting ecological conservation and sustainable development in arid Northwestern China.