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Atomospheric energy and water cycle of Tibetan Plateau

青藏高原大气能与水循环

基本信息

批准号：
11201205
负责人：
ISHIKAWA Hirohiko
金额：
$ 20.1万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11201205/
关键词：
Land surface-atmosphere interaction Tibetan Plateau Asian Monsoon Atmospheric boundary layer Heat and Water circulation Turbulent transport GAME GEWEX 地表面熱吸収気候変動地表面熱収支

项目摘要

The exchange of sensible and latent heat at the interface of atmosphere and the land surface was directly measured by eddy correlation method based on the measurement of atmospheric turbulence. Four flux sites, Amdo, MS3478, BJ(Naqu) and MS3637, were set up and the measurements were conducted during the IOP. In these sites the radiation budget, soil surface temperature, soil temperature profile, soil moisture profile and soil heat flux were also measured. These measured results serve as a consistent database to study land surface-atmosphere interaction.With this results both diurnal and seasonal changes of the sensible and latent heat flux were clearly detected at Amdo where the longest and continuous data was obtained. Before the monsoon the ground surface was very dry and the diurnal change of the surface temperature was as large as 50 degree Celsius. The latent heat flux was very small and the sensible heat flux was dominant As the ground surface became wet after the onset of monsoo … More n, the latent heat flux increased and the sensible heat flux decreased. This change was in harmony with the decease of the ground surface temperature. Typical diurnal change of fluxes was also obtained for pre-monsoon, mid-monsoon and late-monsoon periods (Ishikawa et al, 1999). Tsukamoto et al(2001) compared the flux observation at four sites. They also show that the sensible heat flux controls the development of the depth of mixing layer.At these flux sites, Tanaka et al. (2001a, 2001c), Miyazaki et al. (2001), Wang (2001) and Kim et al. (2001) reported fluximbalance'. They suggest that many factors are responsible for the imbalance. They also stress the importance of mean vertical motion of air mass which may be induced by small scale organized disturbances. Tanaka et al. (2001c) give a discussion on the measurement of soil heat flux. They roughly estimated the surface soil heat flux needed to melt the permafrost and to heat the soil layer from April to June using the soil moisture and temperature data. The required surface heat flux was about 30W/m^2 on average, which was greater than that measured by soil heat plate. Tanaka et al. (2001b) examined the performance of a heat plate numerically and suggested that some correction is necessary to the soil heat flux. The surface imbalance problem has not yet been resolved. This severely limits the usefulness of the observed flux data.The western Tibet is a region where the distribution of meteorological station is very sparse. Two automated meteorological stations were set up at Gaize and Shichuanhe and the continuous measurement of surface boundary layer and some soil variables has been conducted. Haginoya(2001) reported the surface meteorology and fluxes estimated by the Bowen ratio method at these sites. Xu and Haginoya(2001) estimated the monthly averaged surface fluxes at fourteen Tibetan sites using conventional surface observation data. At Amdo site PBL tower observation has been continued after the IOP. Tanaka et al. (2001d) compute the bulk transfer coefficient for the sensible heat flux at the site by comparing the tower data with turbulent flux during IOP. The coefficient is obtained as a function of the bulk Richardson number. With this coefficient and the continued tower observation data they computed the sensible heat flux until July 2000. The data suggests the strong inter annual variation, even the tower observation failed in Spring, when the sensible heat flux is largest in the year. Less

在大气湍流测量的基础上，采用涡动相关方法直接测量了大气与陆面界面的感热、潜热交换。建立了四个通量点，Amdo，MS 3478，BJ（Naqu）和MS 3637，并在IOP期间进行测量。在这些地点还测量了辐射收支、土壤表面温度、土壤温度剖面、土壤湿度剖面和土壤热通量。这些观测结果为研究陆面-大气相互作用提供了一致的数据库，并在获得最长和连续观测资料的安多观测站清晰地观测到了感热通量和潜热通量的日变化和季节变化。季风来临前，地表非常干燥，地表温度日变化高达50 ℃。季风爆发后，由于地面变湿，潜热通量很小，感热通量占主导地位 ...更多信息 n时，潜热通量增大，感热通量减小。这种变化与地表温度的下降是一致的。还获得了季风前、季风中和季风后期通量的典型日变化（石川等人，1999年）。Tsukamoto等人（2001年）比较了四个地点的通量观测。Tanaka等（2001 a，2001 c），宫崎等（2001），Wang（2001）和Kim等（2001）报道了感热通量的平衡。他们认为，造成这种不平衡的因素很多。它们还强调了可能由小尺度有组织扰动引起的气团平均垂直运动的重要性。Tanaka等人（2001 c）对土壤热通量的测量进行了讨论。他们利用土壤湿度和温度数据粗略估计了4月至6月融化永久冻土和加热土壤层所需的表层土壤热通量。所需的地表热通量平均约为30 W/m^2，大于土壤热板实测值。Tanaka等人（2001 b）用数值方法研究了热板的性能，并建议对土壤热通量进行一些修正。表面不平衡问题尚未解决。西藏西部是一个气象台站分布非常稀疏的地区，观测到的通量资料的有效性受到了严重的限制。在改则和石川河建立了两个自动气象站，进行了地面边界层和一些土壤变量的连续观测。Haginoya（2001年）报告了这些地点的地面气象和通过Bowen比率法估算的通量。Xu和Haginoya（2001）利用常规地面观测数据估算了西藏14个站点的月平均地表通量。在Amdo研究中心，IOP后继续观察PBL塔。Tanaka等人（2001 d）通过比较IOP期间的塔数据和湍流通量，计算了现场感热通量的整体传输系数。该系数作为体理查森数的函数获得。利用这个系数和连续的塔观测数据，他们计算了直到2000年7月的感热通量。资料显示，春季感热通量最大，年际变化很大，塔观测失败。少