摘要:为了理解行星反照率时空变化规律及成因，基于CERES数据对全球行星反照率的大气（主要为云与气溶胶等）和地表贡献进行了分解，通过Theil-Sen+Mann-Kendall方法得到了2001～2018年全球行星反照率及其大气和地表贡献的时空变化趋势，并基于回归分析方法对典型区域的变化趋势进行了初步解释。研究结果表明：1）在中低纬度区域行星反照率的大气贡献占主导地位，而在高纬度区域地表贡献相对升高，呈现纬向差异大于经向变化的模式；2）全球行星反照率呈现?0.0002/a（p<0.05）的变化趋势，地表贡献和大气贡献呈现?0.00015/a（p<0.05）与–0.00004/a（p<0.05）的变化趋势；3）大气贡献在火地岛西南洋面等区域呈现显著的增长趋势，而在南极洲东部等区域呈现显著的降低趋势；地表贡献在北冰洋等区域呈现显著的降低趋势，而在南极洲东部等区域呈现显著的升高趋势，并且可以基于云覆盖、积雪覆盖和NDVI等参量的变化有效解释典型区域的行星反照率变化。
关键词:行星反照率/
大气和地表贡献分解/
趋势分析/
CERES数据
Abstract:Planetary albedo is defined as the ratio of the reflected and incident shortwave solar radiation at the top of the atmosphere, and it is also a critical parameter for the surface energy budget and global climate change. To improve our understanding of the spatiotemporal characteristics of the global planetary albedo, this work decomposed the atmospheric and surface contributions of the global planetary albedo using the Clouds and the Earth’s Radiant Energy System data, derived the global planetary albedo trends from 2001 to 2018 using the Theil-Sen+Mann-Kendall method, and explored the driving factors of the planetary albedo in typical regions by the correlation analysis method. Results showed that: 1) In mid-low latitudes (<60°), the atmospheric contribution is the dominant factor to the planetary albedo (89.3%±5%), while in high latitudes (>60°), the surface contribution to the planetary albedo increases with latitude (29%±12%). The spatial distribution of the planetary albedo showed that the zonal variations of the planetary albedo were larger than the meridional variations. 2) A decreasing trend of ?0.0002/a can be observed in the global planetary albedo from 2001 to 2018, and decreasing trends of ?0.00015/a and ?0.00004/a can be found in the surface and atmospheric contribution to the planetary albedo from 2001 to 2018, respectively. The decrease of the global planetary albedo can be largely explained by the decrease of the global cloud fraction. 3) For the atmospheric contribution to the planetary albedo, significant increasing trends can be found in regions of the Sahara Desert and other deserts, and significant decreasing trends can be found in the eastern Antarctic and other locations. For the surface contribution to the planetary albedo, significant increasing trends can be found in eastern Antarctica and other locations, and significant decreasing trends can be found in the Arctic Ocean and other locations. Moreover, the variation of the planetary albedo in typical regions can be effectively explained by the variation of the cloud fraction, snow cover, and the normalized difference vegetation index.
Key words:Planetary albedo/
Decomposition of atmospheric and surface contributions/
Trend analysis/
CERES data
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