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

基于表面辐射温度的整体空气动力学热通量计算方法

• 批准号: 9417959
• 负责人: Jielun Sun
• 金额: $ 23.28万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-11-01 至 1999-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9417959&HistoricalAwards=false
• 关键词: Bulk; Aerodynamic; Method; Heat; Flux

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.

Jielun Sun & L. Mahrt/摘要 ATM-9417959 表面辐射温度是大多数大型现场项目中唯一可用的表面温度，因此用于估计整体空气动力学关系中的垂直温差。 在许多数值模型中，垂直温差是根据表面能量平衡计算出的辐射表面温度来估计的。 这两种应用通常都保留现有的相似性理论，尽管这种相似性理论仅适用于粗糙度高度处的温度。 最近的几项研究表明，表面辐射温度与现有相似理论的结合可能会导致大误差、反梯度通量和/或热量粗糙度高度值过小。 本文献研究建议通过考虑修改现有的相似理论以及表面辐射温度与气动表面温度之间的关系来改善这些问题。 在这些发展之前，必须将表面辐射温度的值替换为表面辐射温度的微尺度分布的函数。 举一个例子，对部分被蒸发植被覆盖的干热地面的温度进行适当的加权，应该可以消除逆梯度热传输的情况。 提出了几种代表表面辐射温度微尺度分布的模型和测量方案。 数据分析将利用多个现场项目的现有塔台和飞机观测结果。 此外，还将与 NCAR ASTER 系统的通量测量一起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来重新评估整体空气动力学公式。 将特别关注与平均流几乎消失的自由对流情况以及弱风条件下的空间平均通量情况相关的问题。