摘要:利用1950～2019年ERA5再分析数据，分析了极端干旱区边界层高度（Boundary Layer Height, BLH）和气候干湿因子（干燥度指数，Aridity Index, AI）的时空变化特征及相互关系。结果表明：BLH年均值为695 m，呈现东高西低的分布特点，BLH在东部升高、西部降低。AI均值为0.03，以塔里木盆地、中心戈壁等地为低值中心向四周递增，AI在东部减小、西部增大。时间变化上，1950～1964年、1965～1993年、2010～2019年，BLH波动降低，AI波动增大，1993～2009年 BLH抬升、AI减小。不同下垫面不同时段两者变化80%的年份呈反位相；两者基本为负相关，其中西部绿洲下垫面相关性最强，相关系数达到－0.79。随着东部BLH的抬升、西部BLH的降低，AI显示70年来极端干旱区的范围整体有向东移动的趋势。
关键词:极端干旱区/
边界层高度/
干燥度指数/
气候变化
Abstract:The temporal and spatial variation characteristics of the boundary layer height (BLH) and climate dryness and wetness factor (Aridity Index, AI) and their relationship in extremely arid areas are analyzed based on the ERA5 (the fifth generation reanalysis product of European Centre for Medium-Range Weather Forecasts) reanalysis data from 1950 to 2019. Results show that the BLH exhibits an average value of 695 m. The distribution characteristics of BLH are high in the east and low in the west. In addition, the BLH rises in the east and decreases in the west. The AI has an average value of 0.03. AI values increase in all directions, with the Tarim Basin and Central Gobi as the center of the low values. Meanwhile, the AI decreases in the east and increases in the west. In terms of temporal changes, the BLH fluctuates lower, and the AI increases from 1950 to 1964, 1965 to 1993, and 2010 to 2019; whereas, the BLH rises and the AI decreases from 1993 to 2009. The BLH and AI have opposite trends at different times in different substrata, with 80% of the years showing inverse phase changes. These two values are basically negatively correlated, with the strongest correlation in the western oasis subsurface, where the correlation coefficient reaches ?0.79. With the rise of the BLH in the east and its decrease in the west, the AI shows that the scope of extreme arid areas has been moving eastward in the recent 70 years.
Key words:Extreme arid region/
Boundary layer height/
Aridity Index/
Climate change
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