CIRA-86 Atmosphere Model

Implement mathematical representation of 1986 CIRA atmosphere

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Libraries:
Aerospace Blockset / Environment / Atmosphere

Description

The CIRA-86 Atmosphere Model block implements the mathematical representation of the 1986 Committee on Space Research (COSPAR) International Reference Atmosphere (CIRA). The block provides values for mean temperature, pressure, and zonal wind speed for the input geopotential altitude.

The CIRA-86 Atmosphere Model block port labels change based on the input and output units selected from the Units list.

Limitations

• This block uses a corrected version of the CIRA data files provided by J. Barnett in July 1990 in ASCII format.

• This block has the limitations of the CIRA 1986 model.

• The CIRA 1986 model that CIRA-86 Atmosphere Model implements limits values to latitudes of 80 degrees S to 80 degrees N on Earth and geopotential heights of 0 to 120 kilometers. The CIRA-86 Atmosphere Model block clips output beyond these ranges.

  The CIRA 1986 model data also has missing data points.

  • In each monthly mean data set, the model omits values at 80 degrees S for 101,300 pascal or 0 meters, because these levels are within the Antarctic land mass.

  • In the annual mean data set for latitudes 70, 75, and 80 degrees S, the model also omits these values:

    • 101,300 and 78,895 pascal

    • 0 and 2,500 meters

  As a result of the missing data points, input for pressures above 61,441 pascal or geopotential heights below 5000 meters at these latitudes generate NaN output.

  For zonal mean pressure in constant altitude coordinates, pressure data is not available below 20 km. This value is the bottom level of the CIRA climatology.

  When the CIRA-86 Atmosphere Model block detects an out-of-range input, the block uses the Action for out-of-range input parameter to determine the block behavior.

Ports

Input

Port_1 — Latitude

array

Contains the latitude in degrees (limited to +/-80 degrees).

Data Types: double

Port_2 — Geopotential heights or pressures

array

Contains an m array of either:

• Geopotential heights in selected length units (Coordinate type is GPHeight)

• Pressures in selected pressure units (Coordinate type is Pressure)

Data Types: double

Output

Port_1 — Mean temperature

array

Mean temperature, specified as an array, in selected units.

Data Types: double

Port_2 — Pressures or geopotential heights

array

m array of either:

• Pressures in selected pressure units (Coordinate type is GPHeight)

• Geopotential heights in selected length units (Coordinate type is Pressure)

Data Types: double

Port_3 — Mean zonal winds

array

Mean zonal winds, specified as an array, in selected units.

Data Types: double

Parameters

Units — Units

Metric (MKS) (default) | English (Velocity in ft/s) | English (Velocity in kts)

Input and output units, specified as:

Units	Height	Temperature	Speed of Sound	Air Pressure	Air Density
Metric (MKS)	Meters	Kelvin	Meters per second	Pascal	Kilograms per cubic meter
English (Velocity in ft/s)	Feet	Degrees Rankine	Feet per second	Pound-force per square inch	Slug per cubic foot
English (Velocity in kts)	Feet	Degrees Rankine	Knots	Pound-force per square inch	Slug per cubic foot

Programmatic Use

Block Parameter: units

Type: character vector

Values: 'Metric (MKS)' | 'English (Velocity in ft/s)' | 'English (Velocity in kts)'

Default: 'Metric (MKS)'

Coordinate type — Coordinate type representation

Pressure (default) | GPHeight

Coordinate type representation, specified as:

• Pressure

  Indicates pressure in pascal.

• GPHeight

  Indicates geopotential height in meters.

Programmatic Use

Block Parameter: ctype

Type: character vector

Values: 'GPHeight' | 'Pressure'

Default: 'GPHeight'

Mean value type — Mean value types

Monthly (default) | Annual

Mean value types, specified as:

• Monthly

  Indicates monthly values. If you select Monthly, you must also set the Month parameter.

• Annual

  Indicates annual values. Valid when Coordinate type has a value of Pressure.

Dependencies

Setting this parameter to Monthly enables the Month parameter.

Programmatic Use

Block Parameter: mtype

Type: character vector

Values: 'Monthly' | 'Annual'

Default: 'Monthly'

Month — Month of mean value

January (default) | February | March | April | May | June | July | August | September | October | November | December

Month in which the mean values are taken.

Dependencies

This parameter is enabled when Mean value type is set to Monthly.

Programmatic Use

Block Parameter: month

Type: character vector

Values: 'January' | 'February' | 'March' | 'April' | 'May' | 'June' | 'July' | 'August' | 'September' | 'October' | 'November' | 'December'

Default: 'January'

Action for out-of-range input — Out-of-range block behavior

None (default) | Warning | Error

Out-of-range block behavior, specified as:

Action	Description
None	No action.
Warning	Warning in the Diagnostic Viewer, model simulation continues.
Error (default)	Error in the Diagnostic Viewer, model simulation stops.

Programmatic Use

Block Parameter: action

Type: character vector

Values: 'None' | 'Warning' | 'Error'

Default: 'Warning'

References

[1] Fleming, E. L., Chandra, S., Shoeberl, M. R., Barnett, J. J., Monthly Mean Global Climatology of Temperature, Wind, Geopotential Height and Pressure for 0-120 km, NASA TM100697, February 1988.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2007b

R2023b: CIRA-86 Atmosphere Model Block Update

The CIRA-86 Atmosphere Model block has been updated to take action when inputs to the function are outside the CIRA 1986 model limitations (see Limitations).