利用“绿洲系统能量与水分循环过程观测试验” 2005年绿洲、戈壁点的观测资料, 分析与讨论了温度、水汽的归一化标准差随稳定度变化的通量方差关系, 应用通量方差法对感热、 潜热通量进行了计算, 并同涡动相关系统的观测结果进行了比较。不稳定条件下, 戈壁点温度归一化标准差随稳定度变化的通量方差关系优于下垫面非均匀性更强的绿洲点, 绿洲点水汽的归一化标准差随稳定度变化的通量方差关系较温度量表现得更好。对同一站点, 归一化温度标准差的通量方差关系并不总是优于水汽的通量方差关系, 其取决于该站点的温度以及水汽的源汇分布情况; 通量方差法对两个站点的感热、 潜热通量均有较好的再现, 但戈壁点感热通量的计算效果优于非均匀性更强的绿洲点。应用通量方差法对潜热通量计算时若采用直接观测的感热通量, 则潜热通量的计算效果具有一定程度的改善。
This study investigated the flux-variance relationships of temperature, water vapor, and examined the performance of this method for calculating sensible heat fluxes (Hs) and latent heat fluxes (LE) with eddy-covariance measured flux data at two different ecosystems: the oasis and the Gobi. The data are taken from “The Oasis System Energy and Water Cycles Field Experiment”, which was held in Jinta County from June 18 to July 8, 2005. Under unstable conditions, the observed standard deviation of temperature as a function of the stability parameter for the Gobi is better than the oasis. Moreover, the oasis site was found to be special, where water vapor follows flux-variance relation better than temperature. For one site, the temperature flux-variance relationship is not always better than the water vapor one, it depends on the sources/sinks distribution at the site; the Hs and LE estimations are found to be in good agreement with the measurements at the two sites, but the accuracy of Hs calculated by the flux-variance method for the Gobi is better than that for the oasis site. The calculation accuracy of LE can be improved if LE is obtained by the flux-variance method in conjunction with measured Hs.