| Based on the annual and seasonal average meteorological observation data of multiyear average temperature,extreme maximum temperature,extreme minimum temperature and precipitation at Linshui station,wusheng station,Guang'an station and Yuechi station in Guang'an City from 1960 to 2020,combined with SPSS software,MATLAB software,Sufer software and Arc GIS software,this paper adopts linear tendency estimation analysis,Mann Kendall mutation detection analysis,wavelet analysis and IDW inverse distance weight interpolation method,The temporal and spatial variation characteristics of climate in Guang'an City in recent 60 years are discussed.The main conclusions are as follows:(1)The annual average temperature of Guang'an City showed an increasing trend from1960 to 2020,with the increasing rate of 0.165?/10 a in the eastern valley and 0.184?/10 a in the western hilly region.The amplitude of the annual mean temperature in the eastern valley was smaller than that in the western hilly region.There was a sudden change in the annual mean temperature,which occurred in 2018.From 1960 to 1964 and from 2015 to 2020,the annual mean temperature showed an increasing trend.From 1965 to 2014,the annual mean temperature showed a downward trend.Besides,the average annual temperature of Linshui station and Wusheng station decreased significantly from 1981 to 1998 and 1981 to 2020.The annual mean temperature has the characteristics of multi-time scale variation during the study period.The valley east of Mt.Huaying has a 4a,9a,15 a,20a,57 a change cycle,while the western hilly region has a 4a,14 a,52a change cycle.In terms of spatial distribution,the average annual temperature shows a low-high-low-high distribution from east to west.The average annual temperature growth rate is higher in the east and west and lower in the middle.(2)In the east and west of Guang 'an city,the trend of average temperature in four seasons is different.The mean temperature of the eastern canyon decreased slightly in summer(-0.006?/10a),but increased in spring and winter(0.15?/10 a,0.122?/10 a and 0.152?/10a).In western China,the mean temperature in spring,summer,autumn and winter showed an upward trend(0.157?/10 a,0.067?/10 a,0.19?/10 a and 0.109?/10 a,respectively).The temperature rise was fast in spring and winter,but slow in summer.The mean temperature of spring,summer,autumn and winter in the eastern Canyon region was abrupt in 2017,1968,1997 and 1998,respectively.Mutation occurred in spring,summer and autumn in western China in 2015,1978 and 1998 respectively,but no obvious mutation occurred in winter.In the eastern part of China,the average temperature in spring,summer and autumn showed a main period of53 a,and a main period of 14 a in winter.The main cycle of 51 a,50a,60 a and 14 a respectively appeared in spring,summer,autumn and winter in western China.In terms of spatial distribution,the mean temperature of four seasons shows a low-high-low-high trend from east to west.In spring,summer and autumn,the growth rate of average temperature in four seasons was west > east > central region,with the fastest growth in eastern region and the slowest growth in central region in winter.(3)The annual maximum temperature in Guang 'an city showed an increasing trend during the study period,and the annual maximum temperature in the eastern valley and the western hills increased by 0.206?/10 a and 0.183?/10 a,respectively.The annual maximum temperature not only changed in 2003,but also had the characteristics of multi-time scale variation.The main period of 3a,8a,19 a and 51 a existed in the eastern valley,and the main period of 3a,8a,16 a and 48 a existed in the western valley.In terms of spatial distribution,the annual maximum temperature in Guang 'an presents a high-low-high distribution from west to east.The maximum temperature growth rate from west to east is slower-fast-slower-fast.(4)The maximum temperature in four seasons in Guang 'an showed an upward trend during the study period,with the fastest rise in summer and the slowest rise in winter.The temperature rise in the eastern valley was faster than that in the western hilly region.In the eastern valley,the annual growth rates of high temperature in spring,summer,autumn and winter are 0.152?/10 a,0.186?/10 a,0.123?/10 a and 0.076?/10 a,respectively.In the western hilly region,the increase rates of high temperature in spring,summer,autumn and winter were 0.145?/10 a,0.148?/10 a,0.168?/10 a and 0.041?/10 a,respectively.The seasonal maximum temperature in Guang 'an city is similar to that in the east and the west.The seasonal maximum temperature in autumn is earlier than that in other seasons,which is located in the early 1990 s,and the other three seasons are all abrupt in the late 2000 s.In the eastern part of China,the seasonal maximum temperature has a main cycle of 53 a,52a,30 a and 33 a respectively,while in the western part,the seasonal maximum temperature has a main cycle of51 a,48a,28 a and 46 a respectively.In terms of spatial distribution,the characteristics of seasonal maximum temperature and annual maximum temperature in Guang 'an city are basically the same,showing a high-low-high trend from west to east.The growth rate of maximum temperature in four seasons shows a slow-fast-slow-fast distribution from west to east.(5)The annual minimum temperature in Guang 'an increased significantly during the study period.The warming rate of the eastern canyon(0.402?/10a)was significantly higher than that of the western hilly region(0.253?/10a),and the amplitude was larger in the eastern part than in the western part.The abrupt change of annual minimum temperature in the eastern valley was earlier than that in the western hilly region,and the abrupt change in the eastern and western regions occurred in 1994 and 2014 respectively.The annual minimum temperature in the eastern canyon has a main cycle of 6a,15 a and 22 a,while the annual minimum temperature in the western canyon has a main cycle of 5a,10 a and 20 a.In spatial distribution,annual minimum temperature showed a high-low-high trend from west to east.The annual minimum temperature growth rate shows a slow-fast-slow-fast distribution from west to east.(6)The seasonal minimum temperature in Guang 'an showed an increasing trend during the study period.The increasing rates of the minimum temperature in spring,autumn and winter in the east(0.229?/10 a,0.3?/10 a,0.309?/10a)were higher than those in the west(0.19?/10 a,0.194?/10 a,0.073?/10a).The increasing rate of summer minimum temperature in the east(0.197?/10a)was smaller than that in the west(0.23?/10a).The abrupt change point of spring minimum temperature in eastern Canyon region occurred in 2016.There were three abrupt changes in summer minimum temperature in 2005,2007 and 2016 respectively.There are two abrupt changes in autumn minimum temperature,which are 1991 and 1992 respectively.A sudden change in winter minimum temperature occurred in 1971.The spring and summer minimum temperatures in western China were abrupt in 2013 and 2012,respectively.The minimum temperature in autumn and winter has no abrupt change point.There are 21 a,22a,16 a and 17 a main cycle of the lowest temperature in spring,summer,autumn and winter in the eastern region,and 52 a,11a,9a and 15 a main cycle of the lowest temperature in spring,summer,autumn and winter in the western region.In terms of spatial distribution,the seasonal minimum temperature and annual minimum temperature showed a high-low-high-low distribution from west to east.The temperature growth rate of the lowest temperature in four seasons is the fastest in the eastern valley region and the slowest in the central hilly region.(7)From 1960 to 2020,the long time series of annual precipitation in Guang 'an city showed an increasing trend.The annual precipitation increase rate is 20.742mm/10 a in the eastern canyon region,19.145mm/10 a in the western hilly region,and 13.852mm/10 a in the central hilly region.The amplitude in the middle and western regions is greater than that in the eastern region.The long time series of annual precipitation in Guang 'an city has obvious mutation characteristics.Eight mutation points appeared in the eastern region,which were 1963,1969,1972,1993,1998,2012,2014 and 2015.There were 6 mutation points in western China,which were 1964,1966,1970,1982,1986 and 2019.In the central region,there were five mutation points,namely 1961,2008,2010,2018 and 2019.The annual precipitation in Guang'an city has the characteristics of multi-time scale variation,and the annual precipitation in the eastern valley has the main cycle of 3a,5a,8a,15 a and 35 a.The annual precipitation in central China has main cycles of 2a,5a,8a,16 a and 31 a.The annual precipitation in the western hilly region has a main cycle of 5a,15 a and 34 a.In the study period,the annual precipitation of Guang 'an city has the characteristics of uneven spatial distribution,showing more in the east and less in the west.The annual precipitation growth rate is positive,but the growth rate is fast in the east and west,and slow in the middle.(8)From 1960 to 2020,spring and summer precipitation in the east,central and west of Guang 'an city showed an upward trend;The variation trend of autumn and winter precipitation is slightly different in eastern,central and western China.In spring,the increasing rates of precipitation in the eastern,western and central regions were 29.711mm/10 a,23.835mm/10 a and 22.105mm/10 a,respectively.In summer,the increasing rates of precipitation in east,west and central China were 43.794mm/10 a,55.21mm/10 a and 34.938mm/10 a,respectively.In autumn,the increasing rates of precipitation in the east,west and central regions were10.69mm/10 a,-2.096mm/10 a and-2.175mm/10 a,respectively.In winter,the increasing rates of precipitation in east,west and central China were-1.228mm/10 a,-0.368mm/10 a and0.538mm/10 a,respectively.In the eastern Canyon region,there were 6 abrupt changes in spring precipitation,which were 1963,1964,1967,2008,2010 and 2013.There were 6 abrupt changes in summer precipitation in 1962,1964,1966,1968,2017 and 2019.There were four abrupt changes in autumn precipitation,namely 1960,1974,2017 and 2020.There are 11 abrupt changes in winter precipitation,which are 1963,1969,1974,1977,1981,2003,2005,2009,2015,2017 and 2018.In the western Hilly region,there were 7 abrupt changes in spring precipitation,which were 1961,1965,1968,1973,1976,2012 and 2014.There were 13 abrupt changes in summer precipitation in 1980,1983,1986,1990,1993,1998,2000,2002,2006,2009,2010,2017 and2018,respectively.There were 8 abrupt changes in autumn precipitation,which were 1960,1962,1963,1966,1967,1971,1973 and 2019.There are seven abrupt changes in winter precipitation,which are 1960,2009,2010,2012,2016,2019 and 2020.In the central Hilly region,there were 8 abrupt changes in spring precipitation,which were1962,1963,1970,1972,1981,1988,1993 and 1995.There were five abrupt changes in summer precipitation in 1961,2009,2011,2017 and 2019,respectively.There were 5 abrupt changes in autumn precipitation in 1976,1978,1980,1982 and 2016,respectively.There are eight abrupt changes in winter precipitation,which are 1961,1968,1970,1977,1979,2013,2018 and 2020.The main periods of spring precipitation in eastern,western and central China are 6a,13 a and 7a,respectively.The main periods of multi-time scale variation of precipitation in summer were 39 a,32a and 55 a,respectively,and the main periods of multi-time scale variation of precipitation in autumn were 23 a,11a and 42 a,respectively.The main periods of multi-time scale variation of precipitation in winter were 33 a,12a and 4a,respectively.The spatial distribution of seasonal precipitation is consistent with the spatial distribution of annual precipitation,which tends to be more in the east and less in the west.In terms of the distribution of precipitation increase rate,spring and autumn tend to be the same,indicating that the precipitation increase rate in the east is greater than that in the west.On the contrary,the precipitation increase rate in the west is greater than that in the east in summer.In winter,the precipitation increasing rate is the largest in the middle part,and the smallest in the east and west. |
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