Temporal-Spatial Distribution And Probability Distribution Of Extreme Temperature In Three Provinces In Northeast China

In recent years,with the global warming,extreme climate events in the three northeastern provinces have occurred frequently,which not only affects people's physical health,but also poses a certain threat to economic development and social stability.Based on the homogenization temperature data of 88 meteorological stations in the three provinces of Northeast China from 1960 to 2012,this paper analyzes the spatial and temporal distribution characteristics of the extreme temperature ten index in the three provinces of Northeast China using linear trend method,empirical orthogonal function(EOF)and wavelet analysis method.Probability distribution function fitting is used to study the probability distribution characteristics of extreme temperatures in the three provinces of Northeast China.The research results can provide theoretical basis and reference for the prediction of extreme temperatures and the formulation of relevant policies for addressing climate change.The main research conclusions are as follows:(1)The results of the trend analysis show that the number of cold days(TX10P),cold nights(TN10P),cold spell duration indicator(CSDI),and frost days(FD0)associated with the lowest temperature in the entire region are mostly throughout the entire region sites have shown a significant reduce over the past 53 years.And the regional average climate trend rate are-2.74days/10a,-7.14days/10a,-0.46days/10a,-3.53days/10a.Warm days(TX90P),warm nights(TN90P),min Tmin(TNn),max Tmax(TXx),warming spell duration indicator(WSDI),and growing season length(GSL)are mostly throughout the entire region sites have shown a significant increase over the past 53 years,and their regional average climate trend rate are 3.23days/10a,8.22days/10a,0.71°C/10a,0.14°C/10a,1.62days/10a,2.46days/10a.Among them,TNn grows faster than TXx.(2)The EOF results show that the spatial distribution characteristics of the extreme temperature indices in the three northeast provinces can be explained by the first two modalities.The eigenvectors of the first modal of all indices show the spatially consistent change of the index.The first mode northeastern provinces cold days(TX10P),cold nights(TN10P),cold spell duration indicator(CSDI),frost days(FD0)were a decreasing trend of volatility;warm days(TX90P),warm night(TN90P),min Tmin(TNn),max Tmax(TXx),warming spell duration indicator(WSDI),and growing season length(GSL)were an increasing trend of volatility.And the overall change range of Heilongjiang Province was greater than that of the other two provinces;the second mode feature vectors showed opposite North and South.The Morlet wavelet analysis results of two modal time coefficients show that except for the cold night hours and the warm night index,the first modal time coefficient has a period of about 4 years,which means most of the extremes.The temperature index has a period of about 4 years.(3)Probability distribution function fitting analysis of extreme temperatures shows that the extreme high temperature sequences can well obey the Gen.Extreme Value distributions,Log-Logistic(3P)distributions,and Fatigue Life(3P)distributions.The cumulative values of the three distribution function K-S test statistics (?)_nD are 6.85,7.04,and 7.15,respectively;the extreme low temperature sequence is well obey Gen.Extreme Value distribution,Error distribution,and Beta distribution,and the cumulative values of the three distribution function K-S test statistics (?)D_n are 6.31,6.81,and 6.84.The optimal distribution of each site is not exactly the same,but the two extreme temperature series are the best for the generalized extreme value distribution.(4)The return period studies show that the root mean square errors between the fitted and measured values of the three distribution functions for the one-time high temperature of50 years are 1.04°C,1.66°C,and 1.11°C,respectively;and for 50 years for one-time low temperature,the root mean square errors between the fitted and measured values of the three distribution functions are 1.57°C,1.61°C,and 1.60°C,respectively.For the 100-year high temperature,the predicted values for the three northeastern provinces using the three distribution functions are 34.5°C~43.5°C,34.9°C~46.5°C,and 34.6°C~44.0°C,respectively.The average value for the entire region is 38.3°C.39.9°C,38.4°C;For the 100-year low-temperature prediction,the predicted value ranges of the three northeastern provinces usingthethreedistributionfunctionsare-51.0°C~-19.9°C,-50.9°C~21.0°C,-50.7°C~-20.2°C,the average value of the whole area was-36.6°C,-36.4°C,-36.1°C.