The Bulk Aerodynamic Method for Heat Flux Based on Surface Radiation Temperature

表面辐射温度是大多数大尺度外场程序中唯一可用的表面温度，因此被用来估计整体空气动力学关系中的垂直温差。在许多数值模式中，垂直温差是根据地表能量平衡计算出的地表辐射温度来估算的。这两种应用大体上都保留了现有的相似理论，尽管这种相似理论仅适用于粗糙度高度的温度。最近的几项研究表明，将地表辐射温度与现有的相似理论结合起来，可能会导致很大的误差，反梯度通量和/或粗糙度高度的荒谬小值。本文的研究建议通过修正现有的相似理论和表面辐射温度与空气动力表面温度之间的关系来改善这些问题。在这些发展之前，必须用表面辐射温度的微尺度分布的函数来代替表面辐射温度的值。例如，适当增加干热地面的温度，部分被蒸腾的植被覆盖，应该会消除逆梯度热量输送的情况。提出了几种描述表面辐射温度微尺度分布的模型和测量方案。数据分析将利用现有的塔台和飞机观测数据，这些数据来自多个现场项目。此外，随着NCAR ASTER系统的通量测量，将对表面辐射温度的微尺度分布进行更集中的测量。将根据改进的表面辐射温度表示法重新评估整体空气动力学公式。将特别注意与近乎为零的平均流量的自由对流情况和弱风条件下的空间平均通量情况有关的问题。

Jielun Sun & L. Mahrt/Abstract ATM-9417959 The surface radiative temperature is the only available surface temperature in most large scale field programs and is therefore used to estimate the vertical temperature difference in the bulk aerodynamic relationship. In many numerical models, the vertical temperature difference is estimated in terms of radiative surface temperature computed from the surface energy balance. Both of these applications generally retain existing similarity theory even though such similarity theory is appropriate only for the temperature at the roughness height. Several recent studies have shown that the combination of surface radiative temperature with existing similarity theory can lead to large errors, counter gradient fluxes and/or absurdly small values of the roughness height for heat. This document research proposes to ameliorate these problems by considering modification of existing similarity theory and relationships between the surface radiation temperature and the aerodynamic surface temperature. These developments must be preceded by replacing the value of the surface radiative temperature with a function of the microscale distribution of the surface radiative temperature. As one example, appropriate weighting of the temperature of hot dry ground, partially covered by transpiring vegetation, should eliminate cases of countergradient heat transport. Several models and measurement schemes or representing the microscale distribution of surface radiation temperature are proposed. The data analysis will take advantage of existing tower and aircraft observations from a number of field programs. In addition, more focused measurements of the microscale distribution of surface radiative temperature will be implemented along with flux measurements from the NCAR ASTER System. The bulk aerodynamic formulation will be re-evaluated in terms of the improved representation of the surface radiation temperature. Special attention will be given to problems associated with the free convection case of nearly vanishing mean flow and the case of spatially- averaged fluxes under weak wind conditions.