干旱区研究

Arid Zone Research ›› 2018, Vol. 35 ›› Issue (6): 1382-1391.doi: 10.13866/j.azr.2018.06.15

• Weather and Climate • Previous Articles     Next Articles

Spatiotemporal Variation of Extreme Climatic Events in the Hulunbuir Grasslands during the Period of 1960-2017

CUI Feng-qi1,2, TANG Hai-ping1,2, ZHANG Qin1,2, DAI Lu-wei1,2   

  1. 1. Faculty of Geographical Science, Beijing Normal University, Beijing 100857, China;
    2. State Key Laboratory of Earth Surface Processes and Resources Ecology, Beijing Normal University, Beijing 100875, China
  • Received:2018-04-24 Revised:2018-06-14 Online:2018-11-15 Published:2025-11-18

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Abstract: Thirteen extreme climatic indices related with regional meteorological disasters and vegetation growth were calculated based on the daily meteorological data from 6 meteorological stations in the Hulunbuir Grasslands and its surrounding area during the period of 1960-2017. The linear trend method, Mann-Kendall test, Sen’s slope estimator and wavelet analysis were used. The results showed that the summer days (SU25), warm nights (TN90P), warm days (TX90P) and continuous warm days (CWD) used to characterize the extreme high temperature increased significantly (P<0.01) with the rates of 3.53 d·(10a)-1, 4.09 d·(10a)-1, 3.1 d·(10a)-1 and 2.67 d·(10a)-1 respectively. The exponential frost days (FD0) and cold nights (TN10P) used to characterize the extreme cold events decreased significantly with the rates of 3.22 d·(10a)-1 and 2.9 d·(10a)-1 respectively (P<0.05). The abrupt change of extreme temperature began from the 1990s. The region with the highest warming rate was located in the northeastern part of the study area. The significant period of extreme high temperature index was concentrated on the scale of 2-9 years. The maximum 5 day precipitation(RX5D)and consecutive wet index (CWD) in the study area were in a significantly decrease trend (P<0.01) with rates of 5 mm·(10a)-1 and 0.2 d·(10a)-1 respectively. The consecutive dry index (CDD) was in a slight increase, and the annual wet day precipitation (PRCPTOT) and precipitation intensity were in a slight decrease trend. The indices used to characterize the extreme precipitation events (common daily intensity index, wet day precipitation , consecutive dry index and maximum 5 day precipitation) were delimited along the central axis of the study area in a north-south direction. The drying index in the eastern region was in a decrease trend. Annual precipitation increased significantly. In the western region, the consecutive dryness index (CDD) increased, and the consecutive wetness index (CWD) decreased significantly.

Key words: extreme climate, extreme precipitation, spatiotemporal variation, Mann-Kendall test, Wavelet analysis, Hulunbuir grasslands