Fig. 4: Simulated results of velocity field, water vapor and liquid water fluxes.

a, b show the vertical profiles of x velocity u; c, d show the z velocity w; e, f show the vertical turbulent water vapor flux \({w}^{{\prime} }{q}_{v}^{{\prime} }\) averaged in y direction; and g, h show the vertical turbulent liquid water flux \({w}^{{\prime} }{q}_{l}^{{\prime} }\) averaged in y direction. Two extreme cases in terms of urban form are displayed: a, c, e, g correspond to compact high-rise urban canopy (LCZ1); b, d, f, h correspond to sparse low-rise urban canopy (LCZ8). LCZs represents local climate zones. Plots are averaged in y direction between the two white dashed lines in Fig. 2. Black dashed lines represent urban-rural interface. Black solid lines represent the top of boundary-layer over the urban area. The height of boundary-layer is defined as the height at which the variance of the vertical velocity fluctuation over urban area \({\sigma }_{w,urban}^{2}\) decreases to 10% of its near-surface maximum⁶⁸.