1997/1998年青藏高原西部地区辐射平衡各分量变化特征

利用中日亚洲季风机制研究计划1997年9月~1998年10月在青藏高原西部改则和狮泉河2个站点自动气象站辐射平衡的观测资料,分析了高原西部2个地区辐射平衡各分量在不同季节的季节平均日变化和年变化特征,并且还与1979年5~8月第一次青藏高原气象科学实验的辐射观测资料和1982,1983年青藏高原辐射平衡观测实验的结果进行了比较分析。结果发现:高原西部辐射平衡各分量的变化不仅有季节之间和年际的差异,高原西部的不同地区之间的变化也有较大的差异:(1)总辐射在春夏两季相差很小,改则春季(3~5月平均)日变化的极大值甚至比夏季(6~8月平均)还大;(2)地表反照率的年际变化及两地之间的差异均可能较大;(3)大气逆辐射日变化、年变化特征与其他辐射分量明显不同,其日变化、年变化的位相均晚于其他分量;(4)两地之间地面辐射平衡的年变化似乎有一个位相差,改则的月平均最大值和最小值均较狮泉河晚了约1个月,因此从冬季到夏季的大部分时间里,改则的地面辐射平衡是小于狮泉河的,而在从夏季到冬季的大部分时间里,改则是大于狮泉河的。

THE VARIATION CHARACTERISTICS OF RADIATION BUDGET COMPONENTS OF THE WESTERN TIBETAN PLATEAU IN 1997/1998

Based on the Automatic Weather Station (AWS) radiation budget observation data of China-Japan Asia Monsoon Mechanism Project on the western Tibetan Plateau in September 1997 and October 1998, the season-mean diurnal variation and annual variation features of the radiation budget components were analyzed on the Gaize and Shiquanhe stations of the west plateau. The results were compared to the Qinghai-Xizang Plateau Meteorological Experiment (QXPMEX) in 1979 and the Plateau heat-source experiment in 1982 and 1983. It shows that the radiation budget components of the western plateau are found except the differences of its seasonal and annual changes, the differences between the regions are probably very important too. For example, (1)the global solar radiation difference between the spring (average from March to May) and summer (average from June to August) were very small, the spring mean diurnal variation maximum was larger than that of the summer at Gaize station;(2)due to the influence of the earth surface condition, the differences of surface albedo were very large in different areas or different years. In December 1997, the values of albedo were as much as 0.5 and 0.57 at Gaize and Shiquanhe, respectively. Their values were 0.24 and 0.23 in August, they were the minimum in annual variation. But in 1979, the albedo was the smallest in July, the value was 0.24, it increased to 0.27 in August. The albedo values of two stations were different, the annual-mean albedo at Gaize station was 0.02 more than that of Shiquanhe; (3)the diurnal and annual variation of the atmospheric counter radiation were different with other components, the phases of the diurnal maximum was 3-4 hours late than global solar radiation and earth surface radiation, the month-mean maximum was 1-2 or 2-3 months late than global solar radiation and earth surface radiation, respectively; (4)the month-mean maximum and minimum of Gaize station were about 1 month late than Shiquanhe, therefore, the radiation budget at Gaize were almost less than Shiquanhe from winter to summer, but they were reverse from summer to winter.