Changes between Version 29 and Version 30 of doc/app/radiation_parameters

Timestamp:

Sep 28, 2018 10:49:59 AM (7 years ago)

Author:

moh.hefny

Comment:

Further changes will follow upon the release of RTM vers. 3.0

doc/app/radiation_parameters

@@ -2 +2 @@
 [[TracNav(doc/app/partoc|nocollapse)]]
 
-For revision r1551 onwards, an interface for use of radiation models is available in PALM. Currently, PALM offers one built-in radiation model for clear-sky conditions, calculating the net radiation at the surface.
-
-All parts of the radiation code (and the interface of the radiation code) are modularized in module [/browser/palm/trunk/SOURCE/radiation_model.f90 radiation_model_mod]. In this context, a new Fortran NAMELIST {{{radiation_parameters}}} was added, containing all radiation-related steering parameters. The radiation module is automatically activated if a {{{radiation_parameters}}} is set in the parameter file ({{{_p3d}}}).
-
-When using the RRTMG radiation model, it is required to [wiki:doc/tec/radiation#Installation compile the radiation code] first as a library. Moreover, the use of netCDF is mandatory.
+PALM offers radiation simulation using a radiation model chosen by the user from these three integrated radiation models:
+* Constant radiation
+* Simple clear sky
+* RRTMG
+In addition to these radiation models, a Radiative Transfer Model (RTM) is implemented in PALM to describe the radiative transfer processes within the urban canopy layer, including multiple reflections between buildings and other surfaces located in the domain. The model treats direct and diffuse radiation separately.
+
+Current RTM (Version 2.0) involves the following processes
+* Calculation of the incoming/outgoing shortwave radiation components on each surface element in the domain
+* Estimation of longwave thermal emission/absorption for all surfaces
+* Reflections of shortwave and longwave radiation by all surfaces (finitely iterated)
+* Partial absorption of shortwave radiation by vegetation (trees)
+
+All parts of the radiation code (and the interface of the radiation code) are modularized in module radiation_model_mod. In this context, a new Fortran NAMELIST radiation_parameters was added, containing all radiation-related steering parameters. The radiation module is automatically activated if a radiation_parameters is set in the parameter file (_p3d). 
+
+When using the RRTMG radiation model, it is required to compile the radiation code first as a library. Moreover, the use of netCDF is mandatory.
 
 \\\\\\\\\\\\\\\\\\\\\\\\\\
@@ -268 +278 @@
 When using RRTMG, shortwave radiation calls can be switched off by setting {{{sw_radiation = .F.}}}. Note that shortwave radiation is automatically switched off during nighttime.
 }}}
+|----------------
+{{{#!td style="vertical-align:top"
+[=#unscheduled_radiation_calls '''unscheduled_radiation_calls''']
+}}}
+{{{#!td style="vertical-align:top"
+L
+}}}
+{{{#!td style="vertical-align:top"
+.T.
+}}}
+{{{#!td
+Parameter to allow additional calls of the radiation code.
+
+Usually the radiation is called each [#dt_radiation], however in case of fast changes in the skin temperature, it is recommended to update the radiative fluxes independently from the prescribed radiation call frequency to prevent oscillations. The value of the temperature threshold used is 0.2 °K. 
+}}}
+|----------------
+{{{#!td style="vertical-align:top"
+[=#max_raytracing_dist '''max_raytracing_dist''']
+}}}
+{{{#!td style="vertical-align:top"
+R
+}}}
+{{{#!td style="vertical-align:top"
+-999.0
+}}}
+{{{#!td
+Maximum distance for raytracing (in meters).
+
+It is used to set the maximum distance allowed to consider the radiative exchange between two surfaces. This limits the number of surfaces view factors (VF) and hence save much memory by neglecting the very small VF resulting from the mutually visible far surfaces. At the end of VF calculations, the values will be scaled so that energy is conserved.
+
+If not set, the model will assume a value equal to double the urban surface layer height. 
+
+Please note that the calculated FV needs to be higher than the threshold value set in [#min_irrf_value] in order to be considered.
+}}}
+|----------------
+{{{#!td style="vertical-align:top"
+[=#min_irrf_value '''min_irrf_value''']
+}}}
+{{{#!td style="vertical-align:top"
+R
+}}}
+{{{#!td style="vertical-align:top"
+1e-6
+}}}
+{{{#!td
+Minimum potential irradiance factor value for raytracing.
+
+It is used to set the threshold to consider any view factor (VF) calculated between two surfaces. This limits the number of VF and hence save much memory by neglecting the very small VF resulting from the low mutual visiblity. At the end of VF calculations, the values will be scaled so that energy is conserved.
+
+Please note that this parameter will neglect any VF smaller than [#min_irrf_value] even though the coressponing surfaces are within the [#max_raytracing_dist].
+}}}
+|----------------
+{{{#!td style="vertical-align:top"
+[=#nrefsteps '''nrefsteps''']
+}}}
+{{{#!td style="vertical-align:top"
+I
+}}}
+{{{#!td style="vertical-align:top"
+0
+}}}
+{{{#!td
+Number of reflection steps to be performed to accound for the refelcted short- and longwave between musually visible surfaces.
+
+Although the effect of reflection depends on the surface characteristics (albedo, emissivity, etc.), however for typical urban areas it is recommended to set {{{nrefsteps = 3}}} because the effect of reflection after 3 reflections is negligible.
+}}}
+|----------------
+{{{#!td style="vertical-align:top"
+[=#mrt_factors '''mrt_factors''']
+}}}
+{{{#!td style="vertical-align:top"
+L
+}}}
+{{{#!td style="vertical-align:top"
+.F.
+}}}
+{{{#!td
+Parameter to generate extra view factors for specific surfaces to calculate MRT during the post processing.
+
+Please note: if set to TRUE, then extra input file (MRT_TARGETS) is needed to set the ID of the surface as well as its coordinates. The model will write out unformated file contains all the mutually visible surfaces for each requested surface along with its type, coordinates, view factor, and transparency.
+}}}
+|----------------
+{{{#!td style="vertical-align:top"
+[=#rma_lad_raytrace '''rma_lad_raytrace''']
+}}}
+{{{#!td style="vertical-align:top"
+L
+}}}
+{{{#!td style="vertical-align:top"
+.F.
+}}}
+{{{#!td
+Parameter to use One-sided communication (MPI-RMA) to access LAD array for raytracing.
+
+For large domain it is recommended to use MPI-RMA to access LAD array for raytracing instead of allocating the global array for each processor. This saves memory and allow for simulations of large domains.
+
+Please note: For Intel compiler, if you observe performance degradation with an MPI application that utilizes the RMA functionality (i.e. {{{rma_lad_raytrace = .TRUE.}}}), you are recommended to set {{{I_MPI_SCALABLE_OPTIMIZATION = 0}}} to get a performance gain.
+}}}
+|----------------
+{{{#!td style="vertical-align:top"
+[=#surface_reflections '''surface_reflections''']
+}}}
+{{{#!td style="vertical-align:top"
+L
+}}}
+{{{#!td style="vertical-align:top"
+.T.
+}}}
+{{{#!td
+Parameter to consider surface-surface reflections.
+
+It is not recommended to set {{{surface_reflections = .F.}}} because When it switched to off, only the effect of building and tree shadows will be considered and all reflection processes will be disabled. However fewer no surface-surface VFs are caclulated and less memory requirement is expected.
+}}}
+|----------------
+{{{#!td style="vertical-align:top"
+[=#svfnorm_report_thresh '''svfnorm_report_thresh''']
+}}}
+{{{#!td style="vertical-align:top"
+R
+}}}
+{{{#!td style="vertical-align:top"
+1e21
+}}}
+{{{#!td
+thresholds of surface view factors normalization values to report.
+
+This array contains 30 values of the histogram steps of logged VF normalization values to show the VF distribution.
+}}}
+|----------------
+{{{#!td style="vertical-align:top"
+[=#radiation_interactions_on '''radiation_interactions_on''']
+}}}
+{{{#!td style="vertical-align:top"
+L
+}}}
+{{{#!td style="vertical-align:top"
+.T.
+}}}
+{{{#!td
+Parameter to force RTM activiation regardless to vertical urban/land surface and trees.
+
+RTM is usually set according to the existance of vertical urban/land surface or trees. If set to FALSE, no RTM is used even when there are vertical urban/land surface or trees in the domain. This simply means that all surfaces will receive radiation fluxes directly from the radiation model without considering other radiation processes such as reflections.
+}}}