近地层能量闭合问题,即测量到的感热和潜热通量之和一般总小于近地层可利用能量(净辐射与土壤热通量之差),是近20年来困扰地气相互作用实验研究的主要难点之一。对国内外有关研究现状做了综述,与解决此问题日益迫切的要求相适应,问题的实质及解决途径近年来已逐渐明朗。“涡动相关方法”应用在复杂的大气湍流通量观测中的局限,特别是对低频较大尺度湍流通量的低估,仍是关键所在。在理论分析的基础上,结合2008年部分“黑河综合实验”资料对有关计算结果做了具体介绍。以阿柔站6天连续资料为例,仔细计算土壤浅层热储存,在涡动相关资料再处理中加上高低频损失修正等,再参考该站大口径闪烁仪(LAS)观测对感热通量的提高,能量闭合率可达到99%,当然这只是个例。许多复杂情况下,较大尺度的涡旋或湍流有组织结构(TOS)会有更明显影响。近地层能量闭合问题的根本解决必须考虑后者的贡献,提高通量观测的时空代表性。
The surface energy balance closure has been one of the major difficulties in the study of surface exchange processes in the last 20 years. Findings from experiments and modeling in recent years have given a much clear understanding of the substantial causes and solving strategies of this issue. Some inabilities of the eddy eovariance system in measuring turbulent fluxes, especially in the underestimation of the contribution from larger eddies in difficult conditions such as inhomogeneous surface and complex terrain, are still the essence. After a brief review of recent progress, as a case study, data from two stations of the comprehensive observation in the Heihe River basin (Project WATER) have been analyzed. One of the unique results for station Arou (on highland pasture), for observations from 1 -6, August 2008, showed that the surface energy balance could be closed almost perfectly. Surely this is only one case. Major efforts still need to be made for a better understanding of the contribution of turbulence organized structures (TOS) , and for a better way to obtain an area averaged fluxes.