半干旱地区地气界面水汽和二氧化碳通量的日变化及季节变化  

Seasonal and Diurnal Variations of the Exchange of Water Vapor and CO_2 Between the Land Surface and Atmosphere in the Semi-Arid Area

作　　者：刘辉志[1] 涂钢[2] 董文杰[3] 符淙斌[1] 石立庆[2] 

机构地区：[1]中国科学院大气物理研究所大气边界层物理和大气化学国家重点实验室,北京100029 [2]中国科学院大气物理研究所东亚区域气候-环境重点实验室 [3]国家气候中心,北京100081

出　　处：《大气科学》2006年第1期108-118,共11页Chinese Journal of Atmospheric Sciences

基　　金：国家重点基础研究发展规划项目2006CB400501

摘　　要：采用涡动相关方法连续观测2002年10月到2003年12月半干旱地区地气界面水汽和二氧化碳通量变化，分析水汽和二氧化碳通量的季节和日变化规律，同时比较农田和退化草地两种不同下垫面物质和能量通量交换过程的差异，得到如下一些主要结果：（1）半干旱地区湿季，相距5km的两种不同下垫面，即使在同一天气过程控制下，不同植被下垫面的降雨分布仍不尽相同，甚至相差很大。这表明降雨空间的分布是很不均匀的，具有很强的局地特征。（2）在干季近地面层能量收支中，两种不同下垫面上的有效能量（净辐射与地表热流量之差）主要分配为感热通量，潜热通量在非生长季（干季）通常很小。在湿季（生长季），潜热通量与感热通量相当，但农田下垫面的潜热通量大于退化草原下垫面。（3）土壤的温度和湿度日变化主要集中在0～20cm土壤层内，在湿季农田下垫面土壤的湿度有明显的跳跃，这与降雨过程有很好的相关。（4）在非生长季，两种不同下垫面地气间二氧化碳通量差别不大，都很小。白天由于光合作用，在生长季农田下垫面吸收CO2通量较退化草原大，但比湿润地区稻田下垫面小一个量级，远小于森林生态系统。Based on the eddy covariance （EC） observation from October 2002 to December 2003 over the semi-arid area （44°25＇N, 122°52＇E, 184 m ASL） in Tongyu, Northeast China over the degraded grassland and the cropland surface, the seasonal and diurnal variations of the exchange of the water vapor and CO2 are investigated. Tongyu ob servation station is also one of the reference sites of the CEOP （Coordinated Enhanced Observing Period）. According to the soil volumetric water content in the surface soil layer, the wet and dry seasons in one year observation are very distinct in the semi arid area. So the annual cycle observation is divided into the two seasons. The wet season is from June to September, while the other is the dry season. The main results are in the following. 1） The rainfall is strongly influenced by the land cover in the semi-arid area and has strong heterogeneity in the wet season, especially during the convective weather system in summer. 2） The latent heat flux is larger over the cropland surface than that over degraded grassland surface in the growing season, while in the dry season their difference is few. The sensible heat flux is the main part of the available energy except that in the wet season in the semi-arid area. In the wet season the latent heat flux has the same order as the sensible heat flux. The albedo over the cropland surface is less than that over the degraded grassland surface in the wet season, while there is no distinct difference over the two land surfaces in the dry season. The net radiation flux has seasonal variation, while in winter it is less than the half of that in summer. The soil heat flux at the ground surface over the cropland surface is smaller than that over the degraded grassland surface in the wet season. The available energy over the cropland surface is larger than that over the degraded grassland surface in the wet season, while in the dry season there is few difference. 3） The soil volumetric water content is less than 15% in the surface s

关 键 词：季节变化 水汽通量 二氧化碳通量 半干旱地区 涡动相关法 

分 类 号：P463[天文地球—大气科学及气象学]