== Radiation Parameters ==
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Since r1551 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 are modularized in module [/browser/palm/trunk/SOURCE/radiation_model.f90 radiation_model_mod]. In this context, a new Fortran NAMELIST {{{radiation_par}}} was added, containing all radiation-related steering parameters. The radiation module is automatically activated when a {{{radiation_par}}} is set in the parameter file ({{{_p3d}}}).

\\\\\\\\\\\\
'''NAMELIST group name: radiation_par''' \\\\

||='''Parameter Name'''  =||='''[../fortrantypes FORTRAN Type]'''  =||='''Default Value'''  =||='''Explanation'''  =||
|----------------
{{{#!td style="vertical-align:top"
[=#albedo '''albedo''']
}}}
{{{#!td style="vertical-align:top"
R
}}}
{{{#!td style="vertical-align:top"
0.2
}}}
{{{#!td
Surface albedo (value of 0-1).
}}}
|----------------
{{{#!td style="vertical-align:top"
[=#day_init '''day_init''']
}}}
{{{#!td style="vertical-align:top"
I
}}}
{{{#!td style="vertical-align:top"
172
}}}
{{{#!td
Day of the year (1-365) at model start. The default value is 172 (June 21).
}}}
|----------------
{{{#!td style="vertical-align:top"
[=#dt_radiation '''dt_radiation''']
}}}
{{{#!td style="vertical-align:top"
R
}}}
{{{#!td style="vertical-align:top"
0.0
}}}
{{{#!td
Timestep of the radiation model (in s).
}}}
|----------------
{{{#!td style="vertical-align:top"
[=#lambda '''lambda''']
}}}
{{{#!td style="vertical-align:top"
R
}}}
{{{#!td style="vertical-align:top"
0.0
}}}
{{{#!td
Geographical longitude (in degrees). 

Note that the radiation scheme also requires information on the geographical latitude (see [wiki:doc/app/inipar#phi]).
}}}
|----------------
{{{#!td style="vertical-align:top"
[=#net_radiation '''net_radiation''']
}}}
{{{#!td style="vertical-align:top"
R
}}}
{{{#!td style="vertical-align:top"
0.0
}}}
{{{#!td
In case of [#radiation_scheme radiation scheme]{{{= 'constant'}}}, {{{net_radiation}}} gives the net radiation at the surface in W/m².
}}}
|----------------
{{{#!td style="vertical-align:top"
[=#radiation_scheme '''radiation_scheme''']
}}}
{{{#!td style="vertical-align:top"
C*10
}}}
{{{#!td style="vertical-align:top"
'clear-sky'
}}}
{{{#!td
Radiation scheme to be used.

The user can choose between the following schemes:

'' 'constant' ''

A constant net radiation at the surface is prescribed (see [#net_radiation]).


'' 'clear-sky' ''

A simple clear sky model is used to calculate the radiation fluxes at the surface (shortwave incoming, shortwave outgoing, longwave incoming, longwave outgoing) and consequently the net radiation at the surface. This scheme required the setting of [#albedo albedo], [#day_init day_init], [#lambda lambda], [wiki:doc/app/inipar#phi phi], [#time_utc_init time_utc_init].


('' 'rrtm' '': not yet implemented.)

}}}
|----------------
{{{#!td style="vertical-align:top"
[=#time_utc_init '''time_utc_init''']
}}}
{{{#!td style="vertical-align:top"
R
}}}
{{{#!td style="vertical-align:top"
43200.0
}}}
{{{#!td
UTC time (in s) at model start, The default value is {{{43200.0}}} (12 p.m., noon).
}}}