南京冬季城、郊下垫面辐射平衡特征对比分析

市区水泥下垫面是城市各种人为下垫面类型中占比重最大的一种且具有典型的城市化特征,其热力性质明显有别于郊区接近自然的下垫面,这必然造成地表辐射平衡和能量交换过程发生改变,对城市气候产生影响。分析城、郊不同下垫面的辐射平衡特征,有助于进一步了解城市气候的成因和影响机制。本文利用在南京冬末开展的"城市边界层三维结构研究"实验所取得的城、郊水汽、温度和地表辐射平衡及分量观测资料,分析了南京城、郊下垫面近地层的辐射平衡及各分量的变化特征,结果表明:①不同天气条件下城、郊辐射平衡及分量特征有一定差异,尤其在天气转折变化时差异更明显,在晴天时差异最大,在下雪天时差异最小,但多云时更接近各辐射分量城、郊差异的平均特征;②净短波辐射在地表辐射平衡城、郊差异日变化中起主导作用;③在冬季多云时的城市"干岛"效应和雪天时的城市"热岛"效应也是影响城市辐射平衡及各分量城、郊对比差异的重要因子。

Charactive Study on Radiation Budget over Urban and Suburban Underlying Surfaces Under Different Weather Conditions in Nanjing

The data related with radiation,aqueous vapor,and air temperature collected at the urban and suburban sites in Nanjing from 17 February to 2 March,2006 are used in this paper to analyze the radiation budget over urban and suburban different underlying surfaces,and the changes of each component,as well as their differences. The results show: (1) the diurnal variation patterns of various radiation components follow the generally observed patterns,and the urban and suburban difference of net short and long wave radiation,and net radiation vary with different weather conditions,with the largest difference in bright days,the least difference in snowing days,and a medium,representative difference in cloudy days; (2) among various radiation components,the net short wave radiation dominates the ground surface radiation budget; (3) both the urban arid island in cloudy days and urban heat island in snowing days in winter are important factors related with the difference of radiation balance and component between urban and suburban sites.