global_environment

global_environment … end_global_environment
global_environment
   land_cover ...
   land_formation ...
   sea_state ...
   wind_speed ...
   wind_direction ...

   wind_table
      <altitude-value> <wind-direction-value> <wind-speed_value>
      ...   // wind_table data sets in order of increasing altitudes.
      ...
   end_wind_table

   cloud_altitude_limits ...
   cloud_water_density ...

   rain_altitude_limit ...
   rain_rate ...

   central_body
     polar_offset_angles
   end_central_body

end_global_environment

Overview

The global_environment block defines the attributes of the global environment. Various objects make use of data defined in this block.

Commands

land_cover <land-cover-type>

Specify the land cover for the receiver clutter model. Valid values are:

  • ::general

  • ::urban

  • ::agricultural

  • ::rangeland_herbaceous

  • ::rangeland_shrub

  • ::forest_deciduous

  • ::forest_coniferous

  • ::forest_mixed

  • ::forest_clear_cut

  • ::forest_block_cut

  • ::wetland_forested

  • ::wetland_non_forested

  • ::desert

Default general

land_formation <land-formation-type>

Specify the land formation for the receiver clutter model. Valid values are:

  • ::level

  • ::inclined

  • ::undulating

  • ::rolling

  • ::hummocky

  • ::ridged

  • ::moderately_steep

  • ::steep

  • ::broken

Default level

sea_state <value>

Specify the sea state for the receiver clutter model. Valid values are 0 - 6.

Degree

Height (m)

Description

0

no wave

Calm (Glassy)

1

0 - 0.10

Calm (Rippled)

2

0.10 - 0.50

Smooth

3

0.50 - 1.25

Slight

4

1.25 - 2.50

Moderate

5

2.50 - 4.00

Rough

6

4.00 - 6.00

Very Rough

Default 0

wind_speed <speed-value>

Specify the wind speed.

Default 0 m/s

wind_direction <angle-value>

Specify the wind direction.

Default 0 deg

Note

WSF wind direction is the direction to which the wind flows; not from where it comes.

wind_table … end_wind_table

Specify wind-value-data sets using 3 parameters per entry (from lowest altitude to highest): :altitude <length-value> wind direction <angle-value> wind speed <speed-value>.

        wind_table
               0 ft    90 deg   20 kts
            5000 ft    95 deg   25 kts
           10000 ft   100 deg   30 kts
           15000 ft   100 deg   35 kts
           20000 ft   120 deg   40 kts
           25000 ft   125 deg   45 kts
           30000 ft   125 deg   50 kts
           35000 ft   130 deg   55 kts
           40000 ft   130 deg   60 kts
        end_wind_table

**Default** If no wind_table, then WSF defaults to values assigned to wind_speed_ and wind_direction_.

.. note::
   WSF wind direction is the direction to which the wind flows; not from where it comes.

.. note::
   Insert altitudes in order from lowest to highest.
cloud_altitude_limits <length-value> <length-value>

Specify the minimum and maximum altitude extent in which clouds are defined to occur. This is used by some attenuation models.

Default 0 m 0 m (no clouds)

cloud_water_density <mass-density-value>

Specify the density of water within the cloud. This is used by some attenuation models.

Default 0 kg/m^3

rain_altitude_limit <length-value>

Specify the altitude below which rain is present. This is used by some attenuation models.

Default 0 m

rain_rate <speed-value>

Specify the rainfall accumulation rate. This is used by some attenuation models.

Default 0 m/s

central_body … end_central_body
central_body <central-body-type>
   polar_offset_angles
end_central_body

Specify the central body and related ellipsoid model to be used by simulation platforms. Options for <central body type> are the following:

  • earth_wgs72 (Earth World Geodetic System 1972): The central body ellipsoid is defined according to the WGS-72 standard.

  • earth_wgs84 (Earth World Geodetic System 1984): The central body ellipsoid is defined according to the WGS-84 standard.

  • earth_egm96 (Earth Gravity Model 1996): The central body ellipsoid is defined according to the EGM-96 standard.

  • moon: The central body ellipsoid is defined according to published lunar parameters.

  • sun: The central body ellipsoid is defined according to published solar parameters.

  • jupiter: The central body ellipsoid is defined according to published Jovian parameters.

Default earth_wgs84

polar_offset_angles <angle-value> <angle-value>

Specify the central_body’s polar offset angles (x_p and y_p, respectively) of the Celestial Intermediate Pole (CIP) with respect to the WCS (ITRS) coordinate system. Providing these values (of the order of tenths of arc-seconds) enables very highly accurate conversions between ECI and WCS coordinates.

Default 0.0 rad 0.0 rad

Note

WCS->LLA conversions are affected by central body choice, as well as sidereal motion transforms calculated in inertial (ECI) coordinate conversions.

polar_offset_angles <angle-value> <angle-value>

Specify the central_body’s polar offset angles (x_p and y_p, respectively) of the Celestial Intermediate Pole (CIP) with respect to the WCS (ITRS) coordinate system. Providing these values (of the order of tenths of arc-seconds) enables very highly accurate conversions between ECI and WCS coordinates.

Default 0.0 rad 0.0 rad