## 2 Materials and Methods
### Different Scale Grid Division Strategy  
#### 2.2.1 Mesoscale Atmospheric Wind Environment Simulation Using WRF  
(1) WRF grid division  
As shown in Figure 5, this study centers on downtown Fuzhou, indicated by the red dot in the figure (119.2751\({}^{\circ}\) E, 26.07557\({}^{\circ}\) N), to simulate the wind fields in its vicinity at a mesoscale level. The simulation area employs a three-layer nested approach, with grid resolutions of 1 km, 3 km, and 9 km from inner to outer layers. Specifically, the outermost layer (d01) is divided into a grid of 91 \(\times\) 91 (9 km), the middle layer (d02) into 109 \(\times\) 109 (3 km), and the innermost layer (d03) into 109 \(\times\) 109 (1 km). The vertical pressure levels range from 1000 hPa to 50 hPa, divided into 43 unevenly spaced layers, with denser layers near the surface. Data extracted at heights of 10 m, 50 m, 100 m, and 200 m above ground level are utilized for CFD boundary conditions. To ensure stable integration, a time step of 12 s is selected for integration.  
Figure 4: Schematic of nesting simulation process.  
Figure 5: WRF regional grid division map.  
Setting of physical schemes  
The boundary layer is an essential part of the wind field structure, and the selection of physical schemes directly affects the accuracy of the simulation results. The choice of physical schemes is closely related to factors such as terrain, season, and resolution. The research in this paper is consistent with the study by [PERSON] [25] in terms of season and both are located in South China. Taking into account the stability of the integration operation, the physical process schemes adopted in this numerical simulation are shown in Table 1. The microphysics parameterization scheme used in the numerical simulation is the [PERSON] scheme, the longwave radiation scheme is the RRTMG scheme, the shortwave radiation scheme is the RRTMG scheme, the surface layer scheme is the Monin-Obukhov scheme, the land-surface process uses the unified Noah land-surface model, and the planetary-boundary-layer scheme is the Mellor-Yamada-Janjic (Eta) TKE scheme.  
Mesoscale wind field measurement points  
In Figure 6, the plan view depicts the measurement points in the d03 region of WRF, which is the innermost layer area. The red \"pentagram\" symbols represent the high-rise buildings to be simulated. Each building has 8 measurement points around it, with a distance of 1 km between each grid node. The CFD simulation area corresponds to the region surrounded by each node. In this study, data are sampled vertically across four layers: 0-10 m, 10-50 m, 50-100 m, and 100-200 m. Specifically, wind data at 10 m height are applied to the interface from 0 to 10 m, data at 50 m are applied to the interface from 10 to 50 m, data at 100 m are applied to the interface from 50 to 100 m, and data at 200 m are applied to the interface from 100 to 200 m. Horizontally, data at the measurement points are applied to the interfaces 1 km to their right.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Scheme** & **Parameter Usage Option** \\ \hline microphysics parameterization scheme & Thompson scheme \\ longwave radiation scheme & RRTMG scheme \\ shortwave radiation scheme & RRTMG scheme \\ near-surface-layer scheme & Monin–Obukhov (Janjic Eta) scheme \\ land-surface process scheme & unified Noah land-surface model \\ planetary-boundary-layer scheme & Mellor–Yamada–Janjic (Eta) TKE scheme \\ \hline \hline \end{tabular}
\end{table}
Table 1: Physical parameterization scheme.  
Figure 6: WRF plane measurement point map.