| Qinling Mountains is a famous mountain lies in the central of China, and also is the important boundary of climate. The study using the data of annual mean monthly temperatures and precipitation between 1959 and 2009 acquired from 33 standard meteorological sites(20 in south and 13 in north) in the region of Qinling Mountains, and the county bounded map and DEM map of study area. Creating the spatial distribution map of Average annual temperature and January temperature in Qinling Mountains with the help of GIS spatial interpolation technique, and using climate trend rate and climate tendency coefficient method to contrastively analyst the trend of temperature and precipitation in levels year,season and month in past 50 years based on the existing climate data. The main study results and progress as follow:(1) the annual mean temperature in the southern and northern regions tended to significantly increased, and the northern regions warmed more significantly.1993 and 2007 are the turning points of the change of annual mean temperature. Except that summer mean temperature tended to faintly decrease, the average temperature of spring, autumn and winter in both regions showed a very significant increasing trend(p<0.01), which the winter and spring mean temperature increased more significantly. The rate and amplitude of seasonal mean temperature in northern regions were faster and greater than those in southern regions, and the seasonal mean temperature between two regions were gradually reduced. Monthly mean temperature from January to May and September to December in southern and northern regions showed an increasing trend, especially February, April and September warming more significantly, which in northern regions warmed more rapidly.The annual precipitation in southern regions of Qinling Mountains showed a decreasing trend that was not pronounced, while which in northern regions tended to faintly decrease. 2007 was a turning point of annual precipitation in northern regions. The spring and autumn precipitation in Qinling Mountains area showed a decreasing trend, and spring precipitation have passed the significant level test(p<0.05); while the summer and winter precipitation showed an increasing trend, which the summer precipitation in northern regions increased significantly(p<0.01). The monthly precipitation of March and April in southern regions of Qinling Mountains significantly reduced; while April precipitation was a significant upward trend and June precipitation has a significant decreasing trend in northern regions.(2) The spatial distribution features of annual mean temperature and January average temperature in Qinling area:The distribution of annual average temperature in Qinling Mountains area is greatly influenced by topography in past 50 years. The spatial distribution of annual mean temperature in Qinling Mountains area is generally present that southern higher than northern. annual mean temperature of the western mountain region is obviously lower than others parts, the center of low temperature lies in the vicinity of Taibai Mountain and the minimum value is 0.35℃; the temperature of Guanzhong plain and parts of Shannan regions is higher than other parts, and the maximum value is 16.25℃. we can show that the temperature of Guanzhong region is higher than Shannan region's by the distribution of temperature.The temperature of Qinling Mountains in January ranged from-11℃to 4℃between 1959 and 1969, the high temperature areas were most concentrated in Shannan regions, and Taibai Mountain area was the center of low temperature.0℃isotherm trend in January was broadly consistent with the run of Qinling Mountains's main vein. The range of temperature in January between 1969 and 1979 was roughly same as that in past 10 years, but there was a small increase in temperature in Guanzhong regions and the range was wide. The temperature in January ranges from-10℃to 4℃between 1979 and 1989, there were a increase trend in temperature in both the southern and northern slope of Qinling Mountains during this period, and the 0℃isotherm was clearly run north, the spatial distribution of temperature between 1989 and 1999 was same as that. The range of increase in temperature is obvious (10℃—5℃)between 1999 and 2009, especially in the valley region of northern slope, the temperature has significanted increased, and was higher than the temperature of the peak with same latitude.(3) Correspondence of 0℃isotherm and elevation in Qinling Mountains in January in past 50 yearsThe 0℃isotherm in January was gradually run north in past 50 years,the average elevation of 5 isotherm in chronological respectively were 1091 meters,1101 meters,1127 meters,1116 meters and 1187 meters, we can show that isotherm was run north in past 50 years, and the corresponding elevation also had a increase trend. |
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