兰州冬季城市烟雾层辐射效应的观测分析研究

Observation and Analysis on the Radiative Effects of the Lanzhou

冬季兰州城市上空形成浓厚的烟雾层。利用1990年11月兰州大学和离城市地面625m高南山顶的辐射和探空资料,分析和计算了烟雾层的辐射效应。兰州城市烟雾层具有浑浊度系数大波长指数小的特点。对到达地面的太阳辐射有很强的削弱。浑浊度系数最大时,烟雾层内的平均加热率为6.16℃/d,。大气层对各波段的消光强弱不同,对可见光削减最大。同时烟雾层使到达兰州地面的大气逆辐射比南山顶增加5.2％,总的入射辐射比南山顶小5.6％,地面辐射差额比南山顶小67.8％。烟雾层的存在增加了城市边界层的稳定性。

In winter, there is a dense smog layer over Lanzhou city. In this paper, use the radiative and sonde data obtained in December 1990 at Lanzhou University and at the top of the South-mountain which is 625 m high to analyse and calculate the radiative effects of the smog layer. The Lanzhou urban smog layer is characterized by a high turbidity coefficient and a low wave length exponent,and decreases the solar radiation significantly. The average heating rate of the smog layer is 6.16 ℃ /dvwith maximum turbidity coefficient. The smog layer has different extinctionsto different wave intervals and has a strongest extinction to the visible part. The smog layer causes the counter radiation reaching Lanzhou surface 5.2% more than that of the South-mountain,total incoming radiation is 5. 6% less than that of the South-mountain,and surface radiation balance is 67. 8% less than that of the South-mountain. The existence of the smog layer increases the stability of the urban boundary layer.