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initialization_parameters

Timestamp:: Sep 15, 2010 3:40:40 PM (14 years ago)
Author:: kanani
Comment:: --

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doc/app/initialization_parameters

-                      v108
+                      v109
     * Potential temperature in buoyancy and stability-related terms is replaced by potential density.[[BR]]
     * Potential density is calculated from the equation of state for seawater after each timestep, using the algorithm proposed by Jackett et al. (2006, J. Atmos. Oceanic Technol., '''23''', 1709-1728).[[BR]]
+    * Potential density is calculated from the equation of state for seawater after each timestep, using the algorithm proposed by Jackett et al. (2006, J. Atmos. Oceanic Technol., 23, 1709-1728).[[BR]]
       So far, only the initial hydrostatic pressure is entered into this equation.[[BR]]
 …
 {{{#!td
 Parameter to switch on longwave radiation cooling at cloud-tops.\\\\
 Long-wave radiation processes are parameterized by the effective emissivity, which considers only the absorption and emission of long-wave radiation at cloud droplets. The radiation scheme can be used only with [#cloud_physics cloud_physics] = ''.TRUE.''.
+Long-wave radiation processes are parameterized by the effective emissivity, which considers only the absorption and emission of long-wave radiation at cloud droplets. The radiation scheme can be used only with [#cloud_physics cloud_physics] = ''.T.''.
 }}}
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 {{{#!td
 Filter factor for the so-called Long-filter.\\\\
 This filter very efficiently eliminates 2-delta-waves sometimes caused by the upstream-spline scheme (see Mahrer and Pielke, 1978: Mon. Wea. Rev., '''106''', 818-830). It works in all three directions in space. A value of '''long_filter_factor''' = ''0.01'' sufficiently removes the small-scale waves without affecting the longer waves.\\\\
+This filter very efficiently eliminates 2-delta-waves sometimes caused by the upstream-spline scheme (see Mahrer and Pielke, 1978: Mon. Wea. Rev., 106, 818-830). It works in all three directions in space. A value of '''long_filter_factor''' = ''0.01'' sufficiently removes the small-scale waves without affecting the longer waves.\\\\
 By default, the filter is switched off (= ''0.0''). It is exclusively applied to the tendencies calculated by the upstream-spline scheme (see [#momentum_advec momentum_advec] and [#scalar_advec scalar_advec]), not to the prognostic variables themselves. At the bottom and top boundary of the model domain the filter effect for vertical 2-delta-waves is reduced. There, the amplitude of these waves is only reduced by approx. 50%, otherwise by nearly 100%.\\\\
 Filter factors with values > ''0.01'' also reduce the amplitudes of waves with wavelengths longer than 2-delta (see the paper by Mahrer and Pielke, quoted above).
 …
 Advection scheme to be used for the scalar quantities.\\\\
 The user can choose between the following schemes:\\\\
 '' 'pw-scheme' ''\\\
+'' 'pw-scheme' ''\\\\
       The scheme of Piascek and Williams (1970, J. Comp. Phys., 6, 392-405) with central differences in the form C3 is used.
       If intermediate Euler-timesteps are carried out in case of [#timestep_scheme timestep_scheme] = '' 'leapfrog+euler' '' the advection scheme is - for the Euler-timestep - automatically switched to an upstream-scheme.\\\\
 '' 'bc-scheme' ''\\\
+'' 'bc-scheme' ''\\\\
       The Bott scheme modified by Chlond (1994, Mon. Wea. Rev., 122, 111-125). This is a conservative monotonous scheme with very small numerical diffusion and therefore very good conservation of scalar flow features. The scheme however, is computationally very expensive both because it is expensive itself and because it does (so far) not allow specific code optimizations (e.g. cache optimization). Choice of this scheme forces the Euler timestep scheme to be used for the scalar quantities. For output of horizontally averaged profiles of the resolved / total heat flux, [../d3par#data_output_pr data_output_pr] = '' 'w*pt*BC' '' / '' 'wptBC' '' should be used, instead of the standard profiles ('' 'w*pt*' '' and '' 'wpt' '') because these are too inaccurate with this scheme. However, for subdomain analysis (see [../d3par#statistic_regions statistic_regions]) exactly the reverse holds: here '' 'w*pt*BC' '' and '' 'wptBC' '' show very large errors and should not be used.\\\\
       This scheme is not allowed for non-cyclic lateral boundary conditions (see [#bc_lr bc_lr] and [#bc_ns bc_ns]).\\\\
 '' 'ups-scheme' ''\\\
+'' 'ups-scheme' ''\\\\
       The upstream-spline-scheme is used (see Mahrer and Pielke, 1978: Mon. Wea. Rev., 106, 818-830). In opposite to the Piascek Williams scheme, this is characterized by much better numerical features (less numerical diffusion, better preservation of flux structures, e.g. vortices), but computationally it is much more expensive. In addition, the use of the Euler-timestep scheme is mandatory ([#timestep_scheme timestep_scheme] = '' 'euler' ''), i.e. the timestep accuracy is only first order. For this reason the advection of momentum (see [#momentum_advec momentum_advec]) should then also be carried out with the upstream-spline scheme, because otherwise the momentum would be subject to large numerical diffusion due to the upstream scheme.\\\\
 Since the cubic splines used tend to overshoot under certain circumstances, this effect must be adjusted by suitable filtering and smoothing (see [#long_filter_factor long_filter_factor]). This is always neccesssary for runs with stable stratification, even if this stratification appears only in parts of the model domain.\\\\
 …
 Time step scheme to be used for the integration of the prognostic variables.\\\\
 The user can choose between the following schemes:\\\\
 '' 'runge-kutta-3' ''\\\
+'' 'runge-kutta-3' ''\\\\
       Third order Runge-Kutta scheme.\\
       This scheme requires the use of [#momentum_advec momentum_advec] = [#scalar_advec scalar_advec] = '' 'pw-scheme'.'' Please refer to the documentation on PALM's time integration schemes (28p., in German) for further details.\\\\
 '' 'runge-kutta-2' ''\\\
+'' 'runge-kutta-2' ''\\\\
       Second order Runge-Kutta scheme.\\
       For special features see '''timestep_scheme''' = '' 'runge-kutta-3'.''\\\\
 '' 'leapfrog' ''\\\
+'' 'leapfrog' ''\\\\
       Second order leapfrog scheme.\\
       Although this scheme requires a constant timestep (because it is centered in time), it is even applied in case of changes in timestep. Therefore, only small changes of the timestep are allowed (see [#dt dt]). However, an Euler timestep is always used as the first timestep of an initial run. When using the Bott-Chlond scheme for scalar advection (see [#scalar_advec scalar_advec]), the prognostic equation for potential temperature will be calculated with the Euler scheme, although the leapfrog scheme is switched on.\\
       The leapfrog scheme must not be used together with the upstream-spline scheme for calculating the advection (see [#scalar_advec scalar_advec] = '' 'ups-scheme' '' and [#momentum_advec momentum_advec] = '' 'ups-scheme' '').\\\\
 '' 'leapfrog+euler' ''\\\
+'' 'leapfrog+euler' ''\\\\
       The leapfrog scheme is used, but after each change of a timestep an Euler timestep is carried out. Although this method is theoretically correct (because the pure leapfrog method does not allow timestep changes), the divergence of the velocity field (after applying the pressure solver) may be significantly larger than with '' 'leapfrog'.''\\\\
 '' 'euler' ''\\\
+'' 'euler' ''\\\\
       First order Euler scheme.\\
       The Euler scheme must be used when treating the advection terms with the upstream-spline scheme (see [#scalar_advec scalar_advec] = '' 'ups-scheme' '' and [#momentum_advec momentum_advec] = '' 'ups-scheme' '').\\\\
 …
 {{{#!td
 Parameter to steer the treatment of the subgrid-scale vertical fluxes within the diffusion terms at k=1 (bottom boundary).\\\\
 By default, the near-surface subgrid-scale fluxes are parameterized (like in the remaining model domain) using the gradient approach. If '''use_surface_fluxes''' = ''.TRUE.,'' the user-assigned surface fluxes are used instead (see [#surface_heatflux surface_heatflux], [#surface_waterflux surface_waterflux] and [#surface_scalarflux surface_scalarflux]) or the surface fluxes are calculated via the Prandtl layer relation (depends on the bottom boundary conditions, see [#bc_pt_b bc_pt_b], [#bc_q_b bc_q_b] and [#bc_s_b bc_s_b]).\\\\
 '''use_surface_fluxes''' is automatically set ''.TRUE.,'' if a Prandtl layer is used (see [#prandtl_layer prandtl_layer]).\\\\
+By default, the near-surface subgrid-scale fluxes are parameterized (like in the remaining model domain) using the gradient approach. If '''use_surface_fluxes''' = ''.T.,'' the user-assigned surface fluxes are used instead (see [#surface_heatflux surface_heatflux], [#surface_waterflux surface_waterflux] and [#surface_scalarflux surface_scalarflux]) or the surface fluxes are calculated via the Prandtl layer relation (depends on the bottom boundary conditions, see [#bc_pt_b bc_pt_b], [#bc_q_b bc_q_b] and [#bc_s_b bc_s_b]).\\\\
+'''use_surface_fluxes''' is automatically set ''.T.,'' if a Prandtl layer is used (see [#prandtl_layer prandtl_layer]).\\\\
 The user may prescribe the surface fluxes at the bottom boundary without using a Prandtl layer by setting '''use_surface_fluxes''' = ''.T.'' and [#prandtl_layer prandtl_layer] = ''.F.''. If , in this case, the momentum flux (u,,*,,^2^) should also be prescribed, the user must assign an appropriate value within the user-defined code (see [[chapter 3.5]]).
 }}}
 …
 {{{#!td
 Parameter to steer the treatment of the subgrid-scale vertical fluxes within the diffusion terms at k=nz (top boundary).\\\\
 By default, the fluxes at nz are calculated using the gradient approach. If '''use_top_fluxes''' = ''.TRUE.,'' the user-assigned top fluxes are used instead (see [#top_heatflux top_heatflux], [#top_momentumflux_u top_momentumflux_u], [#top_momentumflux_v top_momentumflux_v], [#top_salinityflux top_salinityflux]).\\\\
 Currently, no value for the latent heatflux can be assigned. In case of '''use_top_fluxes''' = ''.TRUE.,'' the latent heat flux at the top will be automatically set to zero.
+By default, the fluxes at nz are calculated using the gradient approach. If '''use_top_fluxes''' = ''.T.,'' the user-assigned top fluxes are used instead (see [#top_heatflux top_heatflux], [#top_momentumflux_u top_momentumflux_u], [#top_momentumflux_v top_momentumflux_v], [#top_salinityflux top_salinityflux]).\\\\
+Currently, no value for the latent heatflux can be assigned. In case of '''use_top_fluxes''' = ''.T.,'' the latent heat flux at the top will be automatically set to zero.
 }}}
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 …
 {{{#!td
 Parameter to restrict the mixing length in the vicinity of the bottom boundary (and near vertical walls of a non-flat topography).\\\\
 With '''wall_adjustment''' = ''.TRUE.,'' the mixing length is limited to a maximum of  1.8 * z. This condition typically affects only the first grid points above the bottom boundary.\\\\
+With '''wall_adjustment''' = ''.T.,'' the mixing length is limited to a maximum of  1.8 * z. This condition typically affects only the first grid points above the bottom boundary.\\\\
 In case of  a non-flat topography the respective horizontal distance from vertical walls is used.
 }}}
 …
 Humidity gradient(s) of the initial humidity profile (in 1/100 m).\\\\
 This humidity gradient holds starting from the height level defined by [#q_vertical_gradient_level q_vertical_gradient_level] (precisely: for all uv levels k, where zu(k) > q_vertical_gradient_level, q_init(k) is set: q_init(k) = q_init(k-1) + dzu(k) * '''q_vertical_gradient''') up to the top boundary or up to the next height level defined by q_vertical_gradient_level. A total of 10 different gradients for 11 height intervals (10 intervals if q_vertical_gradient_level(1) = 0.0) can be asigned. The surface humidity is assigned via [#q_surface q_surface].\\\\
 '''Example:'''\\\
+'''Example:'''\\\\
       '''q_vertical_gradient''' = ''0.001,'' ''0.0005,''\\
       [#q_vertical_gradient_level q_vertical_gradient_level] = ''500.0,'' ''1000.0,''\\\\
 …
 Convention for defining the topography grid.\\\\
 Possible values are\\\\
 '' 'cell_edge' ''\\\
+'' 'cell_edge' ''\\\\
       The distance between cell edges defines the extent of topography. This setting is normally for generic topographies, i.e. topographies that are constructed using length parameters. For example, [#topography topography] = '' 'single_building' '' is constructed using [#building_length_x building_length_x] and [#building_length_y building_length_y]. The advantage of this setting is that the actual size of generic topography is independent of the grid size, provided that the length parameters are an integer multiple of the grid lengths [#dx dx] and [#dy dy]. This is convenient for resolution parameter studies.\\\\
 '' 'cell_center' ''\\\
+'' 'cell_center' ''\\\\
       The number of topography cells define the extent of topography. This setting is normally for rastered real topographies derived from digital elevation models. For example, [#topography topography] = '' 'read_from_file' '' is constructed using the input file [../iofiles#TOPOGRAPHY_DATA TOPOGRAPHY_DATA]. The advantage of this setting is that the rastered topography cells of the input file are directly mapped to topography grid boxes in PALM.\\\\
 The example files {{{example_topo_file}}} and {{{example_building}}} in trunk/EXAMPLES/ illustrate the difference between both approaches. Both examples simulate a single building and yield the same results. The former uses a rastered topography input file with '' 'cell_center' '' convention, the latter applies a generic topography with '' 'cell_edge' '' convention.\\\\
 …
 }}}
 {{{#!td
 Switch for the plant_canopy_model.\\\\
+Switch for the plant canopy model.\\\\
 If '''plant_canopy''' is set ''.T.'', the plant canopy model of Watanabe (2004, BLM 112, 307-341) is used.\\
 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!).\\