Climate Change And Its Difference Between Southern And Northern Qinling In Shaanxi Province

The IPCC Fifth Assessment Report(FAR)points out that observed changes in the climate system are higher than those in the previous decades even in the last millennium since 1950,climate change has become a major concern of all sectors of society,the importance of the impact of climate change on the environment and human has caused great concern of the whole society,and attracted a large number of scientists involved in the study.Based on the daily temperature and precipitation data of 35 meteorological stations in Shaanxi Province and NCEP reanalysis data of wind field,using the trend analysis,Mann-Kendall testing,moving average,significance test,Rotated Empirical Orthogonal Function(REOF)and adopting indices of extreme climate published by CCl/CLIVAR/JCOMM Expert Team(ET)on Climate Change Detection and Indices(ETCCDI),the characteristics and distributing of temperature and precipitation changing during 1965 to 2014 in the north and south area of Qinling Mountains in Shaanxi were analyzed,The results are as follows:The results of EOF showed that in terms of cumulative variance contribution rate the first four loading vector fields reflect well the whole structure of the annual temperature and precipitation,which are all passed North test.Therefore,the first four vector vectors are rotated.It shows that the spatial variation of annual temperature and precipitation has the subject consistency,however,the latitudinal and topographic factors have a strong influence on the distribution of air temperature in Shaanxi Province,while the spatial differences of precipitation are influenced not only by latitude and terrain,but also influenced by East Asian summer monsoon,underlying surface and large scale circulation.The results of REOF showed that there are significant differences between the north and south areas of the Qinling Mountains,which indicates that the Qinling Mountains is still of great significance as a boundary line between north and south of China.The average annual temperature,average annual maximum temperature and annual average minimum temperature in the area north of the Qinling Mountains are lower than those in the south of the Qinling Mountains.However,the temperature of the two regions all has an increasing trend,and the annual minimum temperature is the most significant,the temperature mutations occurred around 1994;the cold extreme indices including TN10,TX10 has decreased and the hot extreme indices including TN90,TX90 has increased in the south and north of Qinling,the extreme low temperature events decreased and the extreme high temperature events increased significantly,which reflected the obviously fact that the climate warming in Shaanxi.The difference lies in the temperature increase of northern part of the Qinling Mountains in the past 50 years is higher than that in the south,and the extreme indices in the north of the Qinling Mountains has a stronger trend.The temperature change in this region in night is stronger than that in the daytime,while the south of the Qinling Mountains is almost same.Precipitation has a large fluctuation in the area north of the Qinling Mountains,with an increasing trend of less than 1mm/a.The spatial distribution of the precipitation is increasing from north to south as a whole.The precipitation in the south of the Qinling And the spatial distribution of the spatial distribution is the same as that of the north of the Qinling Mountains.The distribution increases from north to south,and the stratification is obvious.The change of extreme precipitation indices including CDD and CWD indicated that the area north of the Qinling Mountains have shown a wetting trend while the change of extreme precipitation indices including R95 pTOT and Rx1 day indicated that precipitation was more concentrated.The south of the Qinling Mountains has the same wetting tendency as the north of the Qinling Mountains,but the variation range is different,and the wetting tendency of northern Shaanxi is more obvious than that of the south.Both the climate mean and the extreme climate,the northern and southern Qinling Mountains are different,it's closely related to the two circulation systems in Shaanxi area—westerly belt and East Asian monsoon.The southwest of Qinling is mainly influenced by the monsoon system.The southwest monsoon and southeastern monsoon transport warm and humid air to the south of Shaanxi during the flood season,forming warm and humid climatic conditions in this region.During the flood season,the south of Shaanxi is also affected by the monsoon,but it's mainly controlled by the westerlies in the whole year,so the south of Qinling is dominated by dry and cold climate.