TROPICAL GEOGRAPHY ›› 2018, Vol. 38 ›› Issue (5): 660-667.doi: 10.13284/j.cnki.rddl.003067

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Spatio-temporal Variability of Wind Speed in the Yangtze River Basin during 1960-2015

LI Yuejiaa,HE Xinguanga,b,LU Xi’ana,TAN Zifanga   

  1. (a.College of Resources and Environmental Science;b.Key Laboratory of Geospatial Big Data Mining and Application, Hunan Normal University,Changsha 410081,China)
  • Online:2018-09-05 Published:2018-09-05

Abstract:

Based on the monthly wind speed data of 128 meteorological stations during 1960-2015 in the Yangtze River Basin, and five divided sub-regions according to the terrain, the temporal and spatial characteristics of wind speed variation in the Basin are analyzed by using the linear regression estimation, correlation analysis and modified Mann-Kendall (MMK) trend test. The results are as follows: 1) There is a significant weakening trend over the Yangtze River Basin with the average decreasing rate of -0.006 5 m/s·a in annual mean wind speed. The highest annual mean wind speed over the Basin is 2.17 m/s which occurred in 1969, and the least is 1.63 m/s which occurred in 2002. For the five sub-regions, the most significant downward trend occurs in sub-region R1 (hilly and plain areas in the middle and lower reaches), followed by R5 (Qinghai-Tibet Plateau areas in the upper reaches), and the last one is R3 (the basin areas in the upper reaches). 2) Seasonally, in the whole basin, the most significant weakening is found in spring and the least in summer. The trends in the sub-regions are also found that the most weakening is in spring and the least is in summer except for R1 where the most weakening occurs in winter. Furthermore, the non-significantly slightly increasing trends in summer are found in the sub-regions R2 and R3. Monthly, in the Yangtze River Basin, the most significant weakening of wind speed occurs in March, while the most non-significant one is in August. The most significant weakening monthly is also in March in all sub-regions. 3) Spatially, the annual wind speed and its decreasing trend exhibit similar spatial patterns with being the largest in the eastern basin, larger in the western and the smallest in the central, which means that those stations with higher average annual wind speed in Yangtze River Basin also have larger declining rate of wind speed. There are 50% of stations showing the most significant decline that are located in the east of the basin, especially in R1. In addition, there is a similar spatial distribution in trends with respect to seasonal and annual wind speeds. 4) The decrease of mean annual, spring and winter wind speed over the Yangtze River Basin and its sub-regions R1 and R2 is related to the increase of Arctic Oscillation (AO). Over the whole basin and its sub-regions R1 and R2, the correlation coefficients between annual mean wind speed and AO are -0.25, -0.30 and -0.27, respectively, the correlation coefficients between spring wind speed and AO are -0.28, -0.27 and -0.30, respectively, and the correlation coefficients between winter wind speed and AO are -0.29, -0.30 and -0.25, respectively. Besides, the decrease of pressure gradient force in coastal areas may play a role in the decline of winter wind speed in R1. The non-significantly slightly increasing trend in summer in sub-region R3 is possibly caused by an almost unchanged long-term temperature in this area. Moreover, the regional climate warming and urbanization acceleration have also impacts on the decrease of wind speed in the basin

Key words: climate change, wind speed, the Yangtze River Basin, Arctic Oscillation