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Arid Land Geography ›› 2021, Vol. 44 ›› Issue (5): 1199-1212.doi: 10.12118/j.issn.1000–6060.2021.05.01

• Climatology and Hydrology •     Next Articles

Changes of extreme precipitation in Qilian Mountains in recent 60 years

WEN Yuhua1(),LYU Yuemin2,LI Zongxing2()   

  1. 1. Gansu Provincial Party School of CPC (Gansu Administration Institute), Gansu Development Research Institute, Lanzhou 730070, Gansu, China
    2. Key Laboratory of Eco-Hydrology of Inland River Basin, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, Gansu, China
  • Received:2021-01-05 Revised:2021-08-23 Online:2021-09-25 Published:2021-09-22
  • Contact: Zongxing LI E-mail:wenyhua@163.com;lizxhhs@163.com

Abstract:

Using daily precipitation data from 24 meteorological stations in the Qilian Mountains of China from 1961 to 2017, 12 extreme precipitation indices were selected. The linear trend method, Pearson correlation technique, etc. were employed to analyze the temporal and spatial properties of extreme precipitation indices in the Qilian Mountains, and the impact mechanism of altitude with general circulation index on the temporal and spatial variation of extreme precipitation index was evaluated in the Qilian Mountains. (1) The results show that the continuous dry days of the Qilian Mountains, the Hexi inland river basin, the Qaidam inland river basin, and the Yellow River Basin (outflow) exhibited a significant decreasing trend, whereas the continuous wet days exhibited an increasing trend, and the spatial distribution indicated east-west differences. Other extreme precipitation indices exhibited an overall rising trend. The spatial distribution is central in the Qilian Mountains as the area with a larger increase range, and it decreases toward the outer ring. (2) The major reason for the rise in total precipitation is that the number of rainy and moderately rainy days has considerably increased. This precipitation distribution model will increase the probability of intense precipitation events, further confirming that the Qilian Mountains have increased precipitation activities, with a higher frequency and shorter duration of extreme precipitation, as well as the development trend of precipitation in the course of more rainfall days and more concentrated time. The drop in extreme precipitation intensity decreases with the increase in altitude, indicating that extreme precipitation is spatially differentiated. In high-altitude areas, the increase in precipitation and precipitation day is more evident and the decrease in the number of consecutive dry days mainly occurs in high-altitude areas. (3) Among the 11 selected atmospheric circulation anomalies, extreme precipitation in the Qilian Mountains is mainly affected by the AMO index, and the association between AO index and intense precipitation in the Qilian Mountains is the most complicated. The higher the Atlantic sea-level surface temperature index, the lower are the SCSSMI and SAMSMI indices, and the greater is the probability of excess rain and flooding; on the contrary, the probability of less rain is higher.

Key words: Qilian Mountains, climate change, extreme precipitation indices