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

基于大气湍流的测量，通过涡流相关方法直接测量了在大气界面和土地表面界面上明智和潜热的交换。设置了四个通量位点，即AMDO，MS3478，BJ（NAQU）和MS3637，并在IOP期间进行了测量。在这些地点，还测量了辐射预算，土壤表面温度，土壤温度剖面，土壤水分剖面和土壤热通量。这些测得的结果是研究土地表面 - 大气相互作用的一致数据库。在获得最长和最连续数据的AMDO清楚地检测到了明智和潜热通量的昼夜和季节变化。在季风之前，地面非常干燥，表面温度的差分变化高达50摄氏度。潜在热通量非常小，并且敏感的热通量占主导地位，因为地面在Monsoo发作后潮湿……更多N，潜热通量增加，敏感的热通量减少。这种变化与地面温度的衰减相一致。对于季风前，季风和季前后期，还获得了通量的典型昼夜变化（Ishikawa等，1999）。 Tsukamoto等人（2001）比较了四个位点的通量观察。他们还表明，敏感的热通量控制混合层深度的发展。在这些通量部位，田中等人。（2001a，2001c），Miyazaki等。（2001），Wang（2001）和Kim等。（2001年）报道了速气量。他们认为许多因素是导致失衡的原因。他们还强调了空气质量平均垂直运动的重要性，这可能是由小规模有组织的散射引起的。田中等。（2001c）就土壤热通量的测量进行了讨论。他们大致估计了融化多年冻土所需的表面土壤热通量，并使用土壤水分和温度数据从4月到6月加热土壤层。所需的表面热通量平均约为30W/m^2，这比土壤热板测得的表面热通量大。田中等。（2001b）在数值上检查了热板的性能，并建议土壤热通量需要进行一些校正。表面不平衡问题尚未解决。这严重限制了观察到的通量数据的有用性。西藏西部是气象站分布非常稀疏的区域。在Gaize和Shichuanhe建立了两个自动气象站，并进行了一些土壤变量的连续测量。 Haginoya（2001）报道了这些地点的Bowen比率方法估计的表面气象和通量。 Xu and Haginoya（2001）使用常规的表面观察数据估计了14个藏族位点的每月平均表面通量。在IOP之后，在Amdo网站上，PBL塔楼的观察一直在继续。田中等。（2001d）通过将塔数据与IOP期间的湍流进行比较，计算了位置上明智的热通量的整体传输系数。核心是批量理查森号的函数。借助此核心和持续的塔观测数据，他们计算了敏感的热通量直到2000年7月。数据表明年度差异很强，甚至在春季，当敏感的热通量在一年中最大的情况下，塔的观测也失败了。较少的