在北京气象塔上测量城市边界层辐射特征  

Radiation Characteristics of Urban Boundary Layer Measured on the Meteorological Tower in Beijing

作　　者：江玉华[1,2] 王强[3] 张宏升[4] 王正兴[3] 胡波[1] 

机构地区：[1]中国气象局中国气象科学研究院,北京100081 [2]重庆市气象台,重庆401147 [3]中国气象局培训中心,北京100081 [4]北京大学物理学院大气科学系,北京100871

出　　处：《高原气象》2010年第4期918-928,共11页Plateau Meteorology

基　　金：国家自然科学基金项目(40275006)资助

摘　　要：利用2004年10～12月在北京325m气象铁塔上所测量的长波辐射和短波辐射垂直分层资料,分析了晴空、霾(烟、尘、轻雾)和浓雾天气条件下塔上两层的辐射特征。结果表明,城市边界层大气对短波总辐射有明显的衰减作用,2m处的总辐射<280m处的总辐射。在晴好天气下,衰减比例为11.2%;在霾和雾天气下,衰减比例分别达到22.3%和36.6%。在塔上280m处测量的晴天城市地表反照率为0.12,而在霾和雾天气条件下分别为0.17和0.29。大气逆辐射(向下长波辐射)的日变化没有短波辐射的明显且有规律,晴好天气的辐射通量密度最小,霾天较大,雾天最大,2m处的大气逆辐射一般高于280m处的。向上长波辐射呈明显的日变化,且2m处的向上长波辐射日变化幅度>280m处的。净辐射具有典型的日变化,晴天日变化幅度最大,霾和雾天的日变化幅度减小。晴天辐射加热最显著,278m厚气层的辐射加热达1.35℃.h-1,霾天为1.13℃.h-1,雾天为0.40℃.h-1。个例分析表明,在近地面气层内,霾中的气溶胶粒子和雾中的水滴对辐射产生程度不同的影响,并影响到辐射平衡,进而影响不同高度气层的加热和冷却,导致边界层结构的改变。Interaction between atmosphere and land is directly influenced by radiation transfer process in the boundary layer,the vertical radiation changes in urban boundary layer can affect on the local weather and urban climate.The radiation characteristics are investigated with longwave and shortwave radiation data measured at 325 m meteorological tower in Beijing from-October-to December-2004,specifically,the vertical radiation variations among clear,haze （smoke,dust,mist） and fog days are concerned.Results show that-the total radiation-is obviously attenuated by urban boundary layer air,as 2 m compared with 280 m of the total radiation is smaller,the attenuation ratio is 11.2% on the clear day,but it can reach 22.3% in haze and 36.6% in-fog.The surface albedo measured at 280 m layers is 0.12 in the clear day,but it is 0.17 in haze and 0.29 in fog.Daily variation of the atmospheric counter radiation （downward longwave radiation） is less apparent and periodic than the shortwave radiation,the radiation flux density is a minimum value in clear,larger in haze and the largest in fog,the atmospheric counter radiation at 2 m layers is generally higher than that of 280 m.Upward longwave radiation shows obvious daily variation and the amplitude which measured at 2 m layers is greater than that of the 280 m.Net total radiation has a typical daily variation feature;the amplitude is the biggest in clear day,while it becomes smaller in haze or fog.The clear day has-the most significant radiation heating effect,the radiation heating ratio at 278 m thick air is 1.35℃·h-1,1.13℃·h-1 in haze days and 0.40℃·h-1-in fog.Case analysis shows that the aerosol particles in haze and droplets in fog near the surface effect on different radiations,thus affect the radiation balance,it make different heights of the atmosphere heated or cooled,result in the change of boundary layer structure.

关 键 词：城市边界层 霾和浓雾 辐射特征 

分 类 号：P422[天文地球—大气科学及气象学]