| Global warming has changed regional hydrometeorology and has influenced the condition of vegetation,with more frequent extreme weather/climate events.The extreme weather/climate event has significant impacts on economy,natural ecological system,and human life.Therefore,it is of great significance to understand the spatiotemporal characteristics of climatic extremes and their relations with the conditions of vegetation.To further reveal the spatiotemporal characteristics of climatic extremes and their relationship with the condition of vegetation,this study mainly conducted following three researches.The first research is to analyze the spatiotemporal characteristics of extreme weather/climate events over Fujian Province during 1960-2014,based on daily maximum temperature,daily minimum temperature and daily mean temperature records at 23 meteorological stations,using six extreme temperature indices,six extreme precipitation indices,linear trend estimation method,least square method and Mann-Kendall(MK)trend test method.The extreme temperature indices are cold days and cold nights(TX10p),(TN10p),cold duration index(CSDI),warm nights(TN90p),crop growth period(GSL)and day days(TX90p).The extreme precipitation indices are total precipitation(PRCPTOT),the maximum 1 day rainfall(RX1day)Last,the number of precipitation days(CWD),the maximum 5 day rainfall(RX5day)and continuous drought days(CDD).The second content is to analyze the variation of NDVI based on different scales,i.e.,the annual,seasonal and monthly changes of vegetation,by using MOD 13A3 data during the period of 2000-2014 data.The last research content is to connect the variation of NDVI and climatic factors and to analyze the correlations of climate extremes and NDVI during 2000-2014.The results show that:(1)At the regional scale,the cold index decreased,the heating temperature index showed an increasing trend,which is consistent with the trend of global warming.The extreme low temperature event characterization index,cold index continued,cold day days and cold nights,the number of stations decreased the number of stations accounted for 83%.87%and 96%,including cold duration index(P<0.012)and cold nights(P<0.0001)decreased significantly.Characterization of high temperature events during crop growth period,warm days and warm nights days increased,warm days and cold days and day temperature characterization of nighttime temperature variations of warm night days and cold nights is greater than the change the temperature change in the past.The regional average total precipitation,precipitation days,continuous drought days,extreme precipitation index 1 day maximum precipitation and 5 day maximum precipitation show increasing trends,while consecutive wet days shows decrease trend.It suggest that the risk of flooding has increased in this region.(2)The vegetation NDVI showed an overall increase over Fujian Province,which was affected by air temperature is obvious,and reached the highest value in 2014.Meanwhile,the temperature showed an insignificant decrease in interannual variability,while the precipitation increased significantly.In winter and spring,vegetation growth showed an increasing trend,and the increasing trend in winter is significant.It showed an decreasing trend in summer and autumn,and showed the most significant correlation between vegetation growth and temperature.The vegetation in spring is mainly affected by precipitation,but the correlation is not obvious.(3)The correlation analysis of extreme climate index and NDVI show that average vegetation NDVI and extreme temperature index correlation is higher.Among them,the correlation of vegetation NDVI and cold nights is significant at 0.05 level,and the correlation of vegetation NDVI and cold days is significant at 0.01 level.But there is no correlation between vegetation NDVI and extreme precipitation,indicating that the main influence factor of vegetation is temperature and precipitation is the secondary influence factor over Fujian Province. |
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