近48a华北区太阳辐射量时空格局的变化特征

Spatial and temporal variation of solar radiation in recent 48 years in North China

以分析华北区太阳辐射量时空格局变化特征为研究目标,应用国家气象局整编的华北地区120个气象站点48a(1961-2008)的气象资料和中国数字高程模型,对48a来华北地区太阳辐射量进行计算及验证,并对空间格局及变异特征进行了探讨,结果表明:(1)华北地区太阳辐射量的年际间变化较大,总体呈下降趋势,线性倾向值为-7.72 MJ.m-.2a-1;(2)太阳辐射量由多到少突变发生在1981年,1981-2008年太阳辐射量平均值较1961—1981年降低了203.92 MJ.m-.2a-1。从1981年突变年开始,华北地区太阳辐射量表现出明显的下降趋势,且在分析期内,下降的态势得到持续发生;(3)1981/1982年度发生的太阳辐射量由多到少突变,大部分地区突变幅度在150 MJ/m2以上。突变严重的华北中部和南部地区,突变值可达300 MJ/m2;(4)突变年后,华北大部分地区均表现出持续下降的态势,下降速度在6 MJ.m-.2a-1以上,其中华北东北部下降严重,下降速度可达15 MJ.m-.2a-1。

Solar radiation,being the primary energy source for all the biological processes on the earth,is an important factor concerned in many applications due to its essential role as a driving input to agronomic,ecological,hydrological and soil vegetation atmosphere transfer models.Climate change is generally accepted to be one of the most critical problems faced by mankind and it is intricately linked to solar radiation which,as the primary energy source for all of earth′s living organisms,is a major determinant of the productivity of biological systems.North China,as a very important food producing region,is seriously affected by climate change,especially by the changes in solar radiation.Given the above background,the overwhelming emphasis of this study aims to establish the spatial and temporal variation of solar radiation in North China.Based on data of the Chinese Meteorological Administration（CMA） from 1961 to 2008,the geographical coordinates of 120 meteorological stations and the global digital elevation map（GTOPO30,DEM）,we estimated the solar radiation duration between 1961 and 2008 and analysed the spatial pattern and the change in average annual solar radiation in North China.The results showed that the annual solar radiation varied between years,and that there was a linear decreasing trend over the last 48 years： solar radiation was relatively high in 1960s after which it fell by an average of 7.72 MJ·m-2·a-1.During the period analysed,maximum annual solar radiation occurred in 1965 which is about 5173.72 MJ·m-2·a-1,while the minimum occurred in 2003 which is around 4382.51 MJ·m-2·a-1.The result of Mann-Kendall analysis indicated a mutation point in 1981,after which annual solar radiation decreased significantly in North China by an average of 203.92 MJ·m-2·a-1,with a trend that continued until 2008.Solar radiation decreased in most parts of North China with the greatest reductions of more than 300 MJ·m-2·a-1 in central and southern region of North China.There were large spatial differences in the reduction of solar radiation： where as the average decline was 7.72 MJ·m-2·a-1,where as in Beijing,Tianjin,Northern Shandong and Northern Hebei,the average annual reduction was 15 MJ·m-2.The spatial and temporal variation of solar radiation is complex and affected by many factors,including the process of industrialization and urbanization in this region.At same time,the analysis of spatial and temporal variation of solar radiation in the past 48 years in North China can play an important role in the study of potential agricultural productivity,rational prediction of changes in climate,and corresponding decision-making.Considering all these aspects,an attempt should be made to reveal the solar radiation characteristics of main crops in different growth stages in the further work,with the purpose of improving the utilization of agricultural climate resource.