• 关键词：

• 基金项目：

• 雷孝恩
• 中国科学院大气物理研究所

• 邓玉珍
• 中国科学院大气物理研究所

• 摘要：从最简单的二阶闭合假设导出的物质连续方程出发。用近几年来整个行星边界层(PBL)的实测平均风,湍流统计量和拉氏时间尺度随高度和稳定度变化的新结果。对定常的三维方程作数值解,得到一适用于中距离范围的湍流扩散型。该扩散型由纯湍流,地面有效粗糙度,风向切变以及气象参数垂直切变引起的σy随高度和σx随横风方向变化等四个因子组成。在10—100km范围内,扩散型与实测资料和现有的理论扩散型有相当好的一致性。本文的结果无论对PBL内扩散本质的认识还是中距离范围污染模式的建立均有益处。

• Abstract：Based on the newly observed results of variation of the mean wind, the turbulen statistics, and Lagrangian time scales with height and stability categories in the PBL, the stationarity three-dimensional equation of mass continuity which is gained by the second-order closure assumption is solved by a numerical method. A turbulent dispersion pattern which is applicable within the mesoscale range is obtained. The dispersion pattern consists of four factors: the pure turbulence; the effective roughness in length; wind direction shear; and variations of oy with height, a, with crosswind direction, caused by vertical shear of meteorolngioal parameters. In the range of 10-100km, There is good agreement between the dispersion pattern and the experimental data collected, as well as the theoretical results. The results are useful both in understanding turbulent essentials in PBL and establishing pollution models in mesoscale range.

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