Dry and wet climatic change and its driving factors in China

Evaluating the characteristics of long-term dry and wet climate changes under the background of global climate change is important for regional water resources security, ecosystem security and socio-economic development. Based on the daily meteorological data of 1680 meteorological stations in China from 1971 to 2019, the reference evapotranspiration (ET₀) was estimated with the FAO-56 Penman–Monteith equation. Based on which, the temporal and spatial variations of humidity index (HI), precipitation (P), reference evapotranspiration (ET₀) and the driving factors of which were further analyzed. Results showed that HI significantly increased in the northwest China of arid area, the northeast China of subhumid area and the Huang-Huai region of humid area, while it significantly decreased in the southwest and southeast China of humid areas. The change of HI can be mainly attributed to the change of ET₀ while no significant trends has been detected for P for most regions of China. During the past 50 years, the increasing rate of ET₀ was 3.76 mm/10a. But the temporal variation of ET₀ are different from regions, and the increasing and decreasing area were mainly dominated by climate different factors. For region of Huang-huai and northern Northeast China, ET₀ showed significant downward trend. Among factors that relating to ET₀, wind speed contributes most to the significant decrease of ET₀. For all rest regions of China, ET₀ showed significant upward trends, and relative humidity contribute most to the increase.

 

Key words: Dry and wet climatic change, humidity index, reference evapotranspiration, contribution, climatic factors.