Spatiotemporal Characteristics Of Near-surface Wind In Shenzhen

The spatiotemporal characteristics of near-surface wind in Shenzhen were investigated in this study by using the hourly observations at 92 automatic weather stations(AWSs)from 2009 to 2018.It is found that most of the stations showed a decreasing trend in the annual mean of the 10 minute average wind speed(avg-wind)and the mean of the 3 second average wind speed(gust wind).Over half of the decreasing trends at the stations were statistically significant(p <0.05).During the past ten years,the avg-wind speed decreases at a rate of 0.02 m/s per year.Seasonally,the decrease in wind speed was the most severe in spring,followed by autumn,winter,and summer.The distribution of wind speed tends to be greater in the east and coastal areas for both avg-wind and gust wind.However,the distribution pattern of gust factors(GFs)seems to be the opposite of the distribution of the wind speed.The GFs tend to be decline with increasing wind speed.From September to March of the following year,the prevailing wind direction in Shenzhen was northerly,and from April to August,the prevailing wind direction was southerly.The seasonal wind speed distribution exhibited two different types,spring–summer type and autumn–winter type,which may be induced by their different prevailing wind directions.By analyzing the wind speed distribution under different wind directions,it is found that different wind directions will lead to the distinct spatial distribution of wind speed.The analysis by the empirical orthogonal function(EOF)method confirmed the previous findings that the mean wind speed was decreasing in Shenzhen and that two different seasonal wind speed spatial distribution patterns existed.Such a study could provide references for wind forecasting and risk assessment in the study area.