华南沿海地区太阳直接辐射、能见度及大气气溶胶变化特征分析

An Analysis of Direct Solar Radiation, Visibility and Aerosol Optical Depth in South China Coastal Area

分析了中国华南地区福州、广州、海口、南宁等地 1 961～ 1 990年太阳直接辐射总量、日照时数、总云量、大气能见度和地面水汽压等资料 ,并利用这些资料反演了该地区大气气溶胶的光学厚度值。结果表明 :近 30年来 ,华南地区太阳直接辐射总量和日照时数呈明显下降趋势。与 60年代相比 ,80年代各站太阳直接辐射总量的年平均值均下降2 0 %以上 ,其中广州下降 2 9 2 % ;日照时数 ,广州减少了 1 1h ,福州 1h ,南宁 0 9h ,海口 0 5h。分析发现 ,造成下降的原因不是由于云量或大气中水汽含量的变化 ,而是由于地面能见度的明显减小和大气气溶胶的增加。 4站中 ,1 4时地面能见度均以夏季最好 ,最高值出现在 7月 ;而地面能见度最差的季节海口、南宁两站在冬季 ,福州和广州两站在春季3、 4月份。相比较而言 ,海口能见度最好 ,福州和南宁次之 ,广州最差。 4站大气气溶胶光学厚度值的大小、年及季节变化与地面能见度有密切的关系 ,但两者不尽一致 ,因此 ,在研究气溶胶的辐射和气候效应时必须合理地考虑中高层大气气溶胶的分布。

The yearly averaged variation of daily direct solar radiation, sunshine duration, cloud cover, visibility and surface vapor pressure of four cities Fuzhou, Guangzhou, Haikou, and Nanning in South China coastal area are analyzed, and their aerosol optical depth retrieved The results show that in recent 30 years, the direct solar radiation and sunshine duration decreased obviously, which was caused not the enhancement of cloud cover and vapor content, but the decrease of surface visibility and total atmospheric aerosol amounts Compared to 1960s, the total daily direct solar radiation decreased more than 20 percent for each city in 1980s, among them Guangzhou reaches its highest value with 29 2% Meanwhile, the decreases of sunshine duration for four cities are 1 0 h in Fuzhou, 1 1 h in Guangzhou, 0 9 h in Nanning and 0 5 h in Haikou, respectively The best surface visibility occurs in summer for four stations, but the worst in winter for Haikou and Nanning and in spring for the other two stations Among four cities, Haikou is good with its highest visibility, Fuzhou next, then Nanning, and Guangzhou is the worst one The values of aerosol optical depth and its yearly and monthly variation are similar with surface visibility, but the difference still exists So it is important to consider the aerosol distribution in middle and high layers in atmosphere when study aerosol′s radiative and climate forcing