Five urban hydrological processes have been implemented into the SLUCM (sf_urban_physics=1).
1. Oasis effect
Related variables in URBPARM.TBL: OASIS.
This option accounts for enhanced potential evapotranspiration rate of sparse vegetation in urban area due to the lack of obstacles to both radiation and wind. Value should be set to between 1.0 and 2.5. When the value is set to 1.0, the option is deactivated.
2. Urban irrigation
Related variables in URBPARM.TBL: IRI_SCHEME.
This option is used to broadly represent irrigation practice in urban areas. Value should be set to 1 for activation and 0 for deactivation. When activated, irrigation is scheduled for 9 to 10 pm every day from May to September. During this period, moisture of the top two soil layers of the urban vegetation and green roofs will reach critical volumetric soil water content where transpiration is not limited by water availability.
3. Anthropogenic latent heat
Related variables in URBPARM.TBL: ALH, ALHOPTION, ALHSEASON, ALHDIUPRF.
This option models anthropogenic latent heat in urban area and adds it as a diurnal profile to the latent heat flux term. Set ALHOPTION to 1 and 0 for turning on and off the option.
4. Evaporation over impervious surface
Related variables in URBPARM.TBL: IMP_SCHEME, PORIMP, DENGIMP.
This option is used to model evaporation processes over engineered surfaces during and shortly after rainfall events. Set IMP_SCHEME to 1 to use the original parameterization in WRF and to 2 to adopt the new scheme.
5. Multi-layer green roof
Related variables in URBPARM.TBL: GROPTION, FGR, DZGR.
This option enables modeling of multi-layer green roof system on buildings in urban area.
Set GROPTION to 1 and 0 for turning on and off the option. Default vegetation and soil type of green roof is grassland and loam, respectively. FGR (fraction of the green roof) should be greater than 0., and DZGR should not be less than 0.05 m for each layer. The default soil depth of green roof is set to 0.3 m in URBPARM.TBL, and it may be modified based on the application.
Reference: J. Yang, Z-Hu Wang, F. Chen, S. Miao, M. Tewari, J. A. Voogt, S. Myint, 2015: Enhancing HydrologicModelling in the Coupled Weather Research and Forecasting-Urban Modelling System, Boundary-Layer Meteorol, 155,87-109 DOI 10.1007/s10546-014-9991-6.
