城市近地层湍流通量及CO_2通量变化特征  

Characteristics of Turbulent Fluxes and Carbon Dioxide Flux over Urban Surface Layer

作　　者：何文[1,2] 刘辉志[1] 冯健武[1,2] 

机构地区：[1]中国科学院大气物理研究所大气边界层和大气化学国家重点试验室,北京100029 [2]中国科学院研究生院,北京100049

出　　处：《气候与环境研究》2010年第1期21-33,共13页Climatic and Environmental Research

基　　金：国家自然科学基金40575069;中科院知识创新工程KZCX2-YW-219

摘　　要：利用北京325m气象塔47m高度上2006年全年连续观测获得的湍流资料,分析了北京城市近地层动量通量、感热通量、潜热通量和CO2通量的典型日变化、月平均日变化和季节变化特征。分析结果显示:动量通量具有明显的单波峰日变化特征,在15时(北京时间)左右达到最大,季节变化中春季最大,冬季次之,夏、秋季最小;感热通量和潜热通量全年变化范围分别为-92～389W.m-2和-75～376W.m-2,其日变化也表现为单波峰特征。感热通量的日变化受城市下垫面和人为热源影响,入夜后虽然降为负值,但只略小于0。阴雨天感热通量和潜热通量均很小,降雨前后有明显区别。感热和潜热最大值分别在春季3月和夏季6月,最小值都在冬季1月;城市下垫面CO2通量总表现为正值,即净排放,最大值为3.88mg.m-2.s-1,不稳定情况下最小值小于-2mg.m-2.s-1。受到人类活动的影响,CO2通量的日变化特征在工作日与周末有明显区别;由于冬季采暖,CO2通量明显大于夏季;在夜间,CO2通量受进城车辆的影响也出现高值。Diurnal and seasonal variations of turbulence and carbon dioxide flux were investigated based on one year continuous measurements at the height of 47 m on Beijing 325-m meteorological tower. Results showed that the momentum fluxes had a typical diurnal variation characteristic with a single peak in the afternoon around 1500 LST. The momentum fluxes were the largest in spring,followed by winter,then summer and autumn. The sensible and latent heat fluxes throughout a year ranged between -92-389 W·m^-2 and -75-376 W·m^-2,respectively. Typical diurnal variation could be observed obviously in sunny days with a single peak. The sensible heat fluxes usually reduced to a value slightly below zero at night due to the heat released by human. Both of the sensible and latent heat fluxes were small during rainy days and there were clear differences before and after the rain. The maximums of sensible and latent heat fluxes were observed in March and June respectively,with the minimum in January for both. The CO2 flux was mainly positive throughout the year,with the maximum of 3.88 mg·m^-2·s^-1 and the minimum of less than -2 mg·m^-2·s^-1 in unstable conditions. The diurnal variation characteristics of CO2 flux were influenced by human activities. There were obvious differences between weekdays and weekends. Because of human heating,CO2 flux was larger in winter than in other seasons. Peaks of CO2 flux were also observed during the midnight because of the trucks transporting to Beijing.

关 键 词：城市近地层 湍流通量 CO2通量 

分 类 号：P404[天文地球—大气科学及气象学]