Mechanism Of Abrupt Temperature Change And Warming Hiatus And Its Quantitative Response To Water Resources In China

Temperature sudden change and warming stagnation are two important change states in climate change,which will have a certain impact on water resources and ecological environment.The characteristics and laws of large-scale spatio-temporal change,especially the causes and mechanisms,are not clear,and there is still some controversy about whether the real warming stagnation has occurred.Temperature also participates in and affects the hydrological process.After removing the relatively important factors such as precipitation,evaporation and human activities that affect the surface runoff,how much does the sudden change of temperature and warming stagnation affect the surface runoff? Whether the revelation of this effect can provide a reference for some phenomena that are difficult to explain under the conventional response between runoff and main influencing factors,such as stable precipitation and significant reduction of runoff in natural watershed? These are the important research contents and exploration directions that need to be carried out at present.China has a vast territory,many climate types and complex topography.It is highly representative in terms of hydrological and climate change.It is typical to carry out the research on the characteristics and mechanism of temperature sudden change and warming stagnation and its impact on surface runoff.Based on the meteorological data such as average minimum temperature,average temperature,average maximum temperature,precipitation and solar radiation of 622 meteorological stations distributed in China,cmip6 models and measured runoff data of 60 representative hydrological stations,the temporal and spatial variation laws of temperature sudden change and warming stagnation years and their eigenvalues before and after are analyzed by using WBM model and water balance based on Budyko water heat coupling balance theory Mechanism and the quantitative impact of sudden change of temperature and warming stagnation on surface runoff.The main conclusions are as follows:1.The abrupt change time of annual and seasonal temperature in China echoes the world,and there are obvious regional differences.The mutation began in the 1970 s,and the mutation time showed the latitude difference between the early North and the late south.The mutation time of the average minimum temperature was the earliest(1974～2002)and the mutation time of the average maximum temperature was the latest(1980～2006).15 to 15 years after the sudden change of temperature,the temperature in some parts of China has warmed and stagnated.The stagnant years are between 1989 and 2013,mainly in 1998 and2007.The stations without warming and stagnant are concentrated in the south of 40°N.the stagnant time of temperature warming shows the law of the earliest winter and the latest summer.2.Before the abrupt change of annual and seasonal temperatures in China,the three types of temperatures showed a weak upward / downward trend,with a change rate of-0.1℃/ 10 a ～2 ℃/10 a,and the change from southeast to northwest became more and more intense.From the abrupt change of temperature to the stagnation of warming,the temperature in most areas showed a rapid upward trend.The areas with relatively severe temperature changes were concentrated in the temperate continent,plateau and mountainous areas and the northern part of the temperate monsoon climate area.The maximum temperature rise rate was 4.8 ℃/10 a,1.2～4 times the change rate before the abrupt change of temperature.The average maximum temperature was in the east of 100°E and the south of 30°N,showing a downward trend.After the warming and stagnation of the temperature,the change rates of the three types of temperature slow down to close to zero or less than zero,and the maximum decline rate of the average maximum temperature in winter is-4.5 ℃/10 a.3.The three types of interannual temperature sudden change/warming stagnation in China are caused by the continuous enhancement of human activities,the positive / negative phase of PDO and AO,the continuous rise/decline of AMO and SR,and the joint influence of the sudden change of MEI and the continuous decline/rise of WS,AP and RH in various regions.Human activities mainly affect the interannual temperature sudden change/warming stagnation in Northeast and Southeast China,with a contribution rate of 15%～30%,SR,AMO,MEI PDO has the greatest impact on the three types of temperature sudden change/warming stagnation,affecting more than 80% of the whole China.The comprehensive contribution rate to the temperature sudden change/warming stagnation is39%～50% and 23%～41%,and the areas significantly affected by RH,AO,WS and AP account for 40%～60%.It mainly affects the temperature sudden change/warming stagnation in Northeast and Northwest China,and the comprehensive contribution rate to the temperature sudden change/warming stagnation is 40%～59% and 35%～47%.The comprehensive contribution rate of human activities and the selected natural variability factors to the interannual temperature mutation and warming stagnation in China is between56% and 75%.4.In case of abrupt change / warming stagnation of three kinds of seasonal temperatures in China,human activities mainly affect the temperature in Northeast and Southeast China.With the continuous enhancement of human activities,the temperature in each season is abrupt change / warming stagnation,with a contribution of 10% ～ 30%.PDO and AO are in positive / negative phase,AMO and SR continue to rise / fall,and the combined action of MEI mutation and the continuous decline / rise of WS,AP and RH in various regions leads to the sudden change / warming stagnation of seasonal temperature.The abrupt change /warming stagnation of spring temperature is mainly affected by other factors except RH and AP,and the comprehensive contribution rate is about 65%～72%;The abrupt change /warming stagnation of summer temperature is in the south of the Yangtze River,which is greatly affected by human activities,PDO,AMO,MEI and other factors,and the comprehensive contribution rate is more than 65%;The abrupt change / warming stagnation of autumn temperature is in the north of 30°N,which is greatly affected by human activities and some internal variability factors,and the comprehensive contribution rate is between58%～72%;Human activities and internal variability such as AO,WS and AP jointly affect the sudden change / warming stagnation of winter temperature in Northeast China and Inner Mongolia Plateau,with a comprehensive contribution rate of 65%～75%.The comprehensive contribution of human activities and the selected natural variability factors to the abrupt change / warming of seasonal temperature in most parts of China is more than 70%.5.The runoff of most representative hydrological stations in China has been declining for many years.On the whole,the decline rate of runoff in the northern basin is significantly faster than that in the southern region.After mutation,the maximum runoff of some hydrological stations decreased by more than 50%.6.The impact of abrupt temperature change/warming hiatus on runoff is significantly greater than the average impact of temperature on runoff in the whole or regular period,especially in the arid and semi-arid areas and areas including snowmelt runoff in north China,the impact of abrupt temperature change and warming hiatus on runoff is between 8% and15% on average.Before and after the abrupt change,the average temperature difference was between 2℃ and 4℃,and the influence on runoff increased from 3%-8% to 6%-15% after the abrupt change.In some hydrological stations including snowmelt runoff in northwest China,the influence of temperature abrupt change on runoff was up to 20%,which was 1.5times of that before the abrupt change.After the warming stagnation,the temperature still remained high,and the average impact on runoff was 6%-10%.In some natural basins,the impact of temperature abrupt change/warming hiatus on runoff is 8%-12%.In this study the temperature mutations and the stagnation of warming mechanism and its research methods have certain innovation,mutations in the temperature change rule and the stagnation of warming and its effect on surface runoff of the quantitative results have a certain novelty,and main influence factors to explain the runoff under the normal response is difficult to explain some phenomena between provides a new reference,also for the whole of China,It also provides references for further understanding of climate change,coping with water resources and improving ecological environment on a global scale.