Changes between Version 194 and Version 195 of doc/app/initialization_parameters
- Timestamp:
- Feb 13, 2013 2:41:35 AM (12 years ago)
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doc/app/initialization_parameters
v194 v195 2610 2610 Switch for the plant canopy model.\\\\ 2611 2611 If '''plant_canopy''' is set ''.T.'', the plant canopy model of Watanabe (2004, BLM 112, 307-341) is used.\\ 2612 The impact of a plant canopy on a turbulent flow is considered by an additional drag term in the momentum equations and an additional sink term in the prognostic equation for the subgrid-scale TKE. These additional terms are dependent on the leaf drag coefficient (see [#drag_coefficient drag_coefficient]) and the leaf area density (see [#lad_surface lad_surface], [#lad_vertical_gradient lad_vertical_gradient], [#lad_vertical_gradient_level lad_vertical_gradient_level]). The top boundary of the plant canopy is determined by the parameter [#pch_index pch_index]. For all heights equal to or larger than zw(k=pch_index)the leaf area density is 0 (i.e. there is no canopy at these heights!).\\2612 The impact of a plant canopy on a turbulent flow is considered by an additional drag term in the momentum equations and an additional sink term in the prognostic equation for the subgrid-scale TKE. These additional terms depend on the leaf drag coefficient (see [#drag_coefficient drag_coefficient]), and the leaf area density (see [#lad_surface lad_surface], [#lad_vertical_gradient lad_vertical_gradient], [#lad_vertical_gradient_level lad_vertical_gradient_level]). The top boundary of the plant canopy is determined by the parameter [#pch_index pch_index]. For all heights equal or larger than zw(k=pch_index), the leaf area density is 0 (i.e. there is no canopy at these heights!).\\ 2613 2613 By default, a horizontally homogeneous plant canopy is prescribed, if '''plant_canopy''' is set ''.T.''. However, the user can define other types of plant canopies (see [#canopy_mode canopy_mode]).\\\\ 2614 If '''plant_canopy''' and [#passive_scalar passive_scalar] are set ''.T.'', the canopy acts as an additional s ource or sink, respectively, of scalar concentration. The source/sink strength is dependent on the scalar concentration at the leaf surface, which is generally constant with time in PALM and which can be specified by specifying theparameter [#leaf_surface_concentration leaf_surface_concentration].\\\\2615 Additional heating of the air by the plant canopy is taken into account, when the default value of the parameter [#cthf cthf] is altered in the parameter file. In that case the value of [#surface_heatflux surface_heatflux] specified in the parameter file is not used in the model. Instead the near-surface heat flux is derived from an exponential function that is dependenton the cumulative leaf area index.\\\\2616 '''plant_canopy''' = ''.T.'' is only allowed togetherwith a non-zero [#drag_coefficient drag_coefficient].2614 If '''plant_canopy''' and [#passive_scalar passive_scalar] are set ''.T.'', the canopy acts as an additional scalar source or sink, respectively. The source/sink strength depends on the scalar concentration at the leaf surface, which generally does not vary with time in PALM, and which can be specified with parameter [#leaf_surface_concentration leaf_surface_concentration].\\\\ 2615 Additional heating by the plant canopy is taken into account, if the default value of parameter [#cthf cthf] is altered in the parameter file. In that case, the value of [#surface_heatflux surface_heatflux] specified in the parameter file is not used in the model. Instead, the near-surface heat flux is derived from an exponential function that depends on the cumulative leaf area index.\\\\ 2616 '''plant_canopy''' = ''.T.'' is only allowed with a non-zero [#drag_coefficient drag_coefficient]. 2617 2617 }}} 2618 2618 |----------------