陆面近地层湍流通量参数化方法研究

Land-atmosphere interaction is mainly contributed by the surface layer turbulent momentum, heat, moisture and other mass fluxes. Atmospheric circulation model, pollution dispersion model and agricultural ecosystem model all need to calculate surface fluxes accurately. On the basis of having reviewed, reproduced and compared current land surface layer flux parameterization schemes, this project will first carry out data quality control for the turbulent observations over bare soil land, grass land, agricultural field, forest and urban land to form a database which can be used for further theoretical analysis. After that, physical quantities and processes which affect land surface turbulent fluxes transfer, such as aerodynamic roughness length, thermal roughness length, atmospheric stability and roughness sub-layer, will be investigated. The varying range and associated physical mechanisms of land surface aerodynamic and thermal roughness length will be evaluated. Sensitivity experiments will then be carried out to reveal how atmospheric stability and roughness sub-layer affect land surface turbulent flux transfer. With abundant offline and online tests, the surface layer flux parameterization scheme which was developed by us and has been adopted by WRF model will be modified. The research results from this project is expected to support weather forecasting, climate prediction, environment evaluation and agricultural ecosystem research.

陆-气相互作用主要通过近地层湍流动量、热量、水汽和其他物质通量的交换实现。大气环流模式、污染扩散模型和农业生态模型都需要准确地计算近地层湍流通量。在系统地回顾、再现和比较了已有的陆面近地层湍流通量参数化方案的基础之上，本项目将首先对裸土、草地、农田、林地和城市多种陆地下垫面类型的湍流观测资料进行质量控制，形成可用于理论验证的数据集，进而围绕影响陆面近地层湍流通量输送的空气动力粗糙度、热力粗糙度、大气层结稳定度和粗糙子层这些尚未完全明确的关键物理量和物理过程进行研究。我们将定量评估陆面动力和热力粗糙度的取值范围和变化规律，并通过敏感性试验进一步探究大气层结稳定度和粗糙子层对陆面近地层湍流输送的影响，最后进行大量离线和在线测试，完善我们自主研发、并被WRF采用的近地层湍流通量算法。本项目的研究结果可望支撑天气预报、气候预测、环境评价以及农业生态研究。

该项目收集了城市（北京）、农田（安徽省寿县）、裸土（河北省保定市）、沙地（新疆省塔中镇）和冰面（南极中山站）的近地层湍流通量观测资料，形成了包含多种陆面状况的数据集。基于这些观测资料，本项目计算了不同下垫面的动力和热力粗糙度长度，并对前人热力粗糙度长度算法进行了比较和修正。同时基于理论推导，项目组对当前表面层湍流通量算法进行了改进。结合基于观测资料的离线测试及基于中尺度天气数值模式（WRF）的在线测试，本项目完善了当前的近地层湍流通量参数化方案。