WRF/NCAR模拟的夏季长三角城市群区域多城市热岛和地表能量平衡  

Multiple urban heat islands and surface energy balance during summer in Yangtze River Delta city cluster region simulated with WRF/NCAR

作　　者：李欣[1] 杨修群[1] 汤剑平[1] 孙旭光[1] 房佳蓓[1] 

机构地区：[1]南京大学大气科学学院,南京210093

出　　处：《气象科学》2011年第4期441-450,共10页Journal of the Meteorological Sciences

基　　金：国家重点基础研究发展计划(973计划)项目(2010CB428504)

摘　　要：利用一个包含城市冠层效应的区域模式(WRF/NCAR),对长三角特大城市群的夏季气候效应进行了5 a(2003—2007年)高分辨数值模拟,通过长三角地区有无城市的对比试验分析,重点分析了城市群所造成的多城市热岛和地表能量平衡及其日变化特征。结果表明:城市化会导致显著的地表升温,但昼夜不同的升温幅度造成城市地表温度日较差的降低,以及部分郊区日较差增加;城市化也减小城市近地面风速,但沿海城市升温造成的热力差异,增大白天的海风并降低夜间的陆风。同时大范围城市群的热岛能够显著降低低层气压,导致部分海面风速持续的增加;城市下垫面具有很小的潜热通量,但感热通量和热存储量较大,白天的热岛逐渐增加,并在日落前达到最大,夜间热岛基本维持,但在日出前后迅速减弱;较大的入射短波辐射、较小的向下长波辐射和较低的10 m风速能够减弱白天的热岛,而增强夜间的热岛,并且使热岛峰值从17时延后至20时出现;反之亦然。In this study,we have performed high resolution numerical simulations with a regional model with urban canopy module,that is,WRF v3.1.1 developed at NCAR,to examine the climate effect of urbanization in Yangtze River Delta of China.Such an effect is explored by comparing two parallel experiments with and without cities in Yangtze River Delta,with insight into urban heat islands（UHIs）,surface energy balance and their diurnal cycles.The results show that the urbanization not only can raise skin temperature and reduce diurnal temperature range（DTR）and near surface wind speed in urbanized areas,but can increase DTR in some suburban areas.The urban heat island near the coast will increase the daytime sea breeze and decrease the land breeze at nighttime.But large area heat island of city cluster can reduce the low-level pressure which will introduce a higher wind speed on the sea surface all day.Also,the urbanization significantly weakens the latent heat flux（evaporation）and increases the sensible heat flux and heat storage in urbanized areas so that the urban heat islands tend to grow during daytime and to reach peak before sunset,then maintain during night,but decay rapidly around sunrise.Larger incoming short-wave radiation,a smaller downward long-wave radiation and a weaker near surface wind speed are all worked together to reduce UHI during daytime but increase UHI during night,with its peak delayed from 17：00 to 20：00;and vice versa.

关 键 词：城市热岛 地表能量平衡 日变化 

分 类 号：P461.8[天文地球—大气科学及气象学]