青藏高原羊八井地区地表辐射的季节变化特征

Characteristic of Seasonal Variation of Surface Radiation Balance at Yangbajin in Qinghai-Xizang Plateau

利用青藏高原羊八井地区2009-2010年期间地表短波和长波辐射观测数据,分析了该地区地表辐射平衡季节变化特征,重点探讨了该地区云对地表太阳辐射的可能影响。结果表明,羊八井地区长短波辐射均具有显著单峰季节变化特征。短波辐射峰值和谷值分别出现在6月和12月;大气逆辐射和地面长波辐射峰值出现在6—7月,谷值出现在1月,大气逆辐射峰值略晚于地面长波辐射。地表净辐射最高值出现在6月,最低值在12月。羊八井地表反照率日变化特征表现为"U"形分布,地表反照率11月最高,达到0.25;8月最低,仅为0.16。羊八井地区也有总辐射瞬时值超出太阳常数的个例存在,主要出现在夏季。同时,基于实际观测数据进行晴空检测的方法,得出羊八井地区云对总辐射强迫值在-40^-201W·m-2之间变化,年变化幅度较大,其中7月最大、11月最小。

In order to investigate the seasonal variation of surface radiation energy balance and the effect of cloud on the surface downward shortwave radiation at Yabajing station in Qinghai-Xizang Plateau, the shortwave and longwave radiation data which collected by radiometer at Yangbajin station during 2009-- 2010 were used. The result shows that the downward longwave irradiance shows the maximum value in June and the minimum one in January, while the upward longwave radiation shows the maximum value in July and the minimum one in January. The maximum value of surface net irradiance appears in June and minimum one in December. The diurnal variation of surface albedo at Yangbajin shows a ＇U＇ shape distri- bution. It was observed at Yangbajin station that surface irradiance exceeds the solar constant. For the clear sky detection method based on the observation data, the cloud radiative forcing of downward short- wave radiation at Yangbajin has been analyzed. The cloud radiative forcing of downward shortwave radia- tion varies from --40 W· m-2 to --201 W · m-2 and maximum value occurs in June.