Abstract:

Under the global climate change,the frequency of extreme climate events increases gradually.In this context,more and more scholars pay close attention to the change of extreme temperature events.Based on daily temperature at 6 meteorological stations over the Poyang Lake ecoeconomic region observed by the China Meteorological Administration during the 1952-2011,the extreme temperature events were analyzed.The results are as follows.(1) Over the 1952-2011 period, the linear trends of extreme temperature events in the Poyang lake ecoeconomic region were remarkable.The linear trends of extreme high temperature events and extreme low temperature events of this region were 0.4 d/10 a, -2.7 d/10 a;the linear trends of cold and hot days sustainability index were -0.4 d/10 a,-2.4 d/10 a.(2) Over the 60 years,there were obviously two phases in terms of extreme temperature events in the Poyang lake ecoeconomic region:high frequency and low stability phase and low frequency and high stability phase.Two phases of extreme high temperature events and hot day sustainability index were 1952-1979 and 1980-2002;two phases of extreme low temperature events and cold day sustainability index were 1952-1985 and 1986-2007.(3)Wavelets Analysis was used to analyze the periodicities of extreme temperature events in the Poyang lake ecoeconomic region.The results of wavelet analysis indicated that the different kinds of extreme temperature events in the Poyang lake ecoeconomic region had various periodicities in different phase from 1952 to 2011.Extreme high temperature events and hot day sustainability index had a big change from late 1970s to early 1980s.Before that time,it was shown as weak primary 12-13 a periodicity and strong primary 7 a overlying.After that,it was mainly shown primary 9 a periodicity with discontinuous 4-5 a periodicity.Extreme low temperature events and cold day sustainability index had a weak 11-12 a periodicity from 1950s to 1970s,but then changed into a weak primary 5 a periodicity from late 1970s to 1990s.(4) In this study,in order to research the relevance of extreme temperature events in the Poyang lake ecoeconomic region and Asia monsoon change, we compared the extreme low temperature events with Asia winter monsoon and compared extreme high temperature events with Asia summer monsoon, respectively.The extreme low temperature event of this region was a sensitive response of winter monsoon under a global warming background.High frequency and strong fluctuation of extreme low temperature events were mainly seen when the winter monsoon was strong,while low frequency and weak fluctuation were mainly happened when the winter monsoon was weak.Therefore,focusing on the Asia winter monsoon change is a sort of effective way to prevent the disastrous weather which result from extreme low temperature events over the Poyang lake ecoeconomic region.The relevance,however,between extreme high temperature events and summer monsoon is much more complex and still needs further research