1961～2003年中国大陆地表太阳总辐射变化趋势

Changes in Surface Solar Radiation in China's Mainland over the Period from 1961 to 2003

利用中国大陆30个气象站1961～2003年地表太阳总辐射观测数据,研究了辐射年总量和季节总量的变化趋势及其空间分布特征,并探讨了其原因。结果表明:1961～1989年中国大陆地表太阳总辐射总体呈减少趋势,减少约11%;1990～2003年间略有回升,但其均值仍比1961～1965年的均值低8.2%。大部分地区春夏两季减少明显,约占年减少量的55%～85%。对各站点观测数据的趋势分析表明,地表太阳总辐射随时间的变化大致可分为4种类型,其特征分别为:1961～2003年间持续减少(占总站点数20%);20世纪60年代初到80年代中期呈显著减少趋势,其后线性趋势不明显(占总站点数40%)或呈逐步增加趋势(占总站点数16.7%);1961～2003年间无显著变化(占总站点数23.3%)。这4种类型在空间分布上无明显的区域特征。日照时数减少是总辐射减少的主要原因,可以解释地表太阳辐射年总量变化的72%,日照时数随风速的增大而增加。

Using the datasets from 30 observational stations over China's Mainland,the authors studied the changes in annual and seasonal amounts of surface solar radiation from 1961 to 2003 and the spatial characteristics.Cause of the changes was discussed.The results indicated that surface solar radiation in China's Mainland decreased by approximately 11% from the early 1960s to the late 1980s in general,but increased slightly during 1990-2003.Nevertheless,the mean value of surface solar radiation over 1990-2003 was 8.2% lower than that over 1961-1965.Significant decrease occurred in the period from March to August,accounting for 55%-85% of the annual reduction.Analysis of the datasets for each station suggested that the trend in changes of surface solar radiation with time could be roughly identified as four groups with the characteristics of decreasing continuously(6 out of 30 stations)or leveling off(7 out of 30 stations)over the period from 1961 to 2003,and decreasing significantly from the early 1960s to the mid 1980s and leveling off thereafter(12 out of 30 stations)or increasing gradually thereafter(5 out of 30 stations).The four groups have no significant regional feature in spatial distribution.A main cause of the reduction in solar radiation is the decreasing sunshine duration.Approximately 72% of the variability in the solar radiation can be expressed by the sunshine duration which is positively correlated with wind speed.