Aridity Changes and Related Climatic Drivers in Drylands of China during 1960-2019

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  • 1 Guangdong Meteorological Public Service Center, Guangzhou, China
  • 2 School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing, China
  • 3 Key Laboratory of Transportation Meteorology, China Meteorological Administration, Nanjing, China
  • 4 Jiangsu Institute of Meteorological Sciences, Nanjing, China
  • 5 Nanjing Joint Institute for Atmospheric Sciences, Nanjing, China
  • 6 School of Geographic Sciences, Nanjing University of Information Science and Technology, Nanjing, China
  • 7 Department of Plant and Soil Sciences, University of Kentucky, Lexington, USA
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Abstract

Drylands cover about half of the land surface in China and are highly sensitive to climate change. Understanding climate change and its impact drivers on dryland is essential for supporting dryland planning and sustainable development. Based on meteorological observations (period: 1960-2019), the aridity changes in drylands of China were evaluated using aridity index (AI), and the impact of various climatic factors (i.e., precipitation, P; sunshine duration, SSD; relative humidity, RH; maximum temperature, Tmax; minimum temperature, Tmin; wind speed, WS) on the aridity changes was decomposed and quantified. Results of trend analysis based on Sen’s slope estimator and Mann–Kendall test indicated that the aridity trends were very weak averaged over whole drylands in China during 1960-2019, but exhibited a significant wetting trend in hyper-arid and arid regions of drylands. AI was most sensitive to changes in water factors (i.e., P and RH), followed by SSD, Tmax and WS, but the sensitivity of AI to Tmin was very small and negligible. Interestingly, the dominant climatic driver to AI change varied in the four dryland subtypes. The significantly increased P dominated the increase in AI in the hyper-arid and arid regions. While the significantly reduced WS and the significantly increased Tmax contributed more to AI changes than the P in the semi-arid and dry subhumid regions of drylands. Previous studies emphasized the impact of precipitation and temperature on the global or regional dry-wet changes, however, the findings of this study suggested that beyond precipitation and temperature, the impact of wind speed on aridity changes of drylands in China should be given equal attention.

Corresponding author: Xinfa Qiu, xfqiu135@nuist.edu.cn

Abstract

Drylands cover about half of the land surface in China and are highly sensitive to climate change. Understanding climate change and its impact drivers on dryland is essential for supporting dryland planning and sustainable development. Based on meteorological observations (period: 1960-2019), the aridity changes in drylands of China were evaluated using aridity index (AI), and the impact of various climatic factors (i.e., precipitation, P; sunshine duration, SSD; relative humidity, RH; maximum temperature, Tmax; minimum temperature, Tmin; wind speed, WS) on the aridity changes was decomposed and quantified. Results of trend analysis based on Sen’s slope estimator and Mann–Kendall test indicated that the aridity trends were very weak averaged over whole drylands in China during 1960-2019, but exhibited a significant wetting trend in hyper-arid and arid regions of drylands. AI was most sensitive to changes in water factors (i.e., P and RH), followed by SSD, Tmax and WS, but the sensitivity of AI to Tmin was very small and negligible. Interestingly, the dominant climatic driver to AI change varied in the four dryland subtypes. The significantly increased P dominated the increase in AI in the hyper-arid and arid regions. While the significantly reduced WS and the significantly increased Tmax contributed more to AI changes than the P in the semi-arid and dry subhumid regions of drylands. Previous studies emphasized the impact of precipitation and temperature on the global or regional dry-wet changes, however, the findings of this study suggested that beyond precipitation and temperature, the impact of wind speed on aridity changes of drylands in China should be given equal attention.

Corresponding author: Xinfa Qiu, xfqiu135@nuist.edu.cn
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