结构分层

两种粗糙表面流动的过度 简单划分示意图

https://www.dmu.dk/atmosphericenvironment/cost/docs/WG2_final.pdf

Sketch of the urban boundary layer structure indicating the various (sub)layers and their names (from Rotach et al., 2004a; modified after Oke, 1987).

H.j.s. Fernando. Fluid Dynamics of Urban Atmospheres in Complex Terrain[J]. Annual Review of Fluid Mechanics, 2010

z0 粗糙长度

• 由多个样本计算得粗糙长度后取平均，结果优于多个样本取平均后求粗糙长度。
• 粗糙长度随风速增大而减小
• 边界层气象学中footprint是一种非常好的反应测风点上风向粗糙边界情况的方法（https://wenku.baidu.com/view/a6f58ac6a8956bec0975e394.html）
• 关于粗糙度，《建筑结构荷载规范》GBJ50009作了以下规定：以拟建房屋为中心、2km为半径的迎风半圆影响范围内的房屋和密集度来区分粗糙度类别，风向以该地区主导风向为准。

Bulk Richardson number （BRN）详见此处

The Bulk Richardson Number (BRN) is an approximation of the Gradient Richardson number, which formed by approximating local gradients by finite difference across layers.

The BRN is a dimensionless ratio in meteorology related to the consumption of turbulence divided by the shear production (the generation of turbulence kinetic energy caused by wind shear) of turbulence. It is used to show dynamic stability and the formation of turbulence.

Bulk Richardson number