Time-scale analyses of heat/water vapor/carbon dioxide transport in the lower atmosphere

本文研究了森林-大气界面上蒸散发、感热通量和CO_2吸收在时间和空间（或频率）上的尺度依赖性。在项目的最后一年2007财年，对林业和林产研究所藤吉下实验站的密集观测数据进行了分析，并对数据采用了地表更新法。该方法使用森林冠层与相邻大气之间的热和质量交换的概念模型形式化地表通量。在本年度，研究了地表更新形式化中使用的垂直长度尺度作为稳定性函数的模型。此外，为了与森林冠层上的结果进行比较，利用不同土地覆被上的数据考察了尺度依赖性。对蒙古草原和落叶松森林的数据分析表明，与森林相比，草地的地表能量平衡和CO_2吸收量受降水量和雨后土壤湿度的影响更大（Li, et. Al., 2007）。对青藏高原某草原湍流数据的分析表明，边界层深度尺度上的对流活动会影响温度和湿度波动，并使它们之间的相似性变差（涡旋扩散系数相等，Asanuma, et. Al., 2007）。将小波变换应用于日本稻田的数据，结果显示了湍流和中尺度运动间隙周围尺度上大气与地面之间的热量和水汽交换特征（Saito, et. Al., 2007）。这些结果在一些学术会议上发表，如日本水文水资源学会和日本农业气象学会（Iwata, et. Al., 2007a, 200b, Saito, et. Al., 2007a, 2007b, Asanuma, et. Al., 2007a, 2007b）。少

This study investigates the scale-dependence, both in time and space (or frequency), of the evapotranspiration, sensible heat flux, and CO_2 uptake at the forest-atmosphere interface. In FY 2007, the last year of the project, the data obtained during an intensive observation made at Fujiyoshita experiment station of the Forestry and Forest Products Research Institute were analyzed, and the surface renewal method was applied to the data. The method formalizes surface flux using a conceptual model of heat and mass exchange between the forest canopy and the atmosphere adjacent to it. During this FY, models of the vertical length scale as a function of the stability used in the surface renewal formalization was investigated.Moreover, in order to compare with the result above the forest canopy, the scale-dependence was investigated with the data obtained over various land covers. Analyses of the data obtained over a grassland and larch forest in Mongolia revealed that the surface energy bal … More ance and the CO_2 uptake at the grassland is influenced more strongly by the amount of precipitation and the soil moisture after the rainfall than those at the forest (Li, et. Al., 2007). Analyses of turbulence data obtained at a grassland over Tibetan plateau indicates that the convective activities at the scale of the boundary layer depth affect the temperature and humidity fluctuations and deteriorate the similarity between them (equality of the eddy diffusivities, Asanuma, et. Al., 2007). Wavelet transform was applied to the data obtained over a rice paddy field in Japan, and the results show the characteristics of the heat and water vapor exchange between the atmosphere and the land surface at the scale around the gap between the turbulence and mesoscale motions (Saito, et. Al., 2007).These results were presented at some academic conferences, such as that of Japanese Society of Hydrology and Water Resources and the Society of Agricultural Meteorology of Japan (Iwata, et. Al., 2007a, 200b, Saito, et. Al. 2007a, 2007b, Asanuma, et. Al., 2007a 2007b). Less