Summary:
Mesoscale local weather fashions present indispensable instruments to know land-atmosphere interactions over city areas. Nonetheless, uncertainties in city cover parameters (UCPs) and parameterization schemes result in degraded illustration of the drag impact in complicated constructed terrains. Specifically, for the extensively utilized single-layer city cover mannequin (SLUCM) coupled with the Climate Analysis and Forecasting (WRF) mannequin, near-surface horizontal wind velocity is thought to be overestimated systematically. On this research, idealized massive eddy simulations (LES) and WRF-SLUCM simulations are carried out to review the separate impact of UCPs and aerodynamic parameterization on atmospheric boundary layer processes and rainfall variabilities in Phoenix, Arizona. For LES that explicitly resolves floor geometry, vital variations between three-dimensional (3D) versus two-dimensional (2D) illustration of city morphology are discovered within the floor layer and above. When floor drag is parameterized following SLUCM, floor morphologies have little impacts on the imply momentum switch. WRF-SLUCM simulation outcomes, included with 3D city morphology information, point out that merely refining the frontal space index will cut back the floor drag, which additional amplifies the systematic constructive bias of SLUCM in predicting horizontal wind velocity. Changing the drag parameterization in SLUCM by LES-based aerodynamic parameters has evident impacts on near-surface wind velocity. The affect of city roughness illustration turns into probably the most evident throughout rainfall intervals, as a result of necessary position of floor drag in dictating moisture convergence. Our research underlines that aside from intensive efforts in acquiring detailed UCPs, additionally it is vital to boost the city momentum change parameterization schemes.
