atmosisa

Use International Standard Atmosphere model

Syntax

[T,a,P,rho,nu,mu] = atmosisa(height)

[T,a,P,rho,nu,mu] = atmosisa(height,Name=Value)

Description

[T,a,P,rho,nu,mu] = atmosisa(height) implements the mathematical representation of the International Standard Atmosphere values for ambient temperature, T, pressure, P, speed of sound, a, density, rho, kinematic viscosity, nu, and dynamic viscosity mu, for the input geopotential altitude, height, between the sea level and the tropopause.

[T,a,P,rho,nu,mu] = atmosisa(height,Name=Value) specifies options using one or more name-value arguments. For example, to input geopotential altitude between -5000 meters and the mesopause, set extended to true.

Examples

Calculate International Standard Atmosphere at One Height

Calculate the International Standard Atmosphere at 1000 m.

[T, a, P, rho] = atmosisa(1000)

T = 
281.6500

a = 
336.4341

P = 
8.9875e+04

rho = 
1.1116

Calculate International Standard Atmosphere at Multiple Heights

Calculate the International Standard Atmosphere at 1000, 11,000, and 20,000 m with extended=true to implement the mathematical representation of the International Standard Atmosphere values to between -5000 meters and the mesopause.

[T, a, P, rho] = atmosisa([1000 11000 20000],extended=true)

T = 1×3

  281.6500  216.6500  216.6500

a = 1×3

  336.4340  295.0695  295.0695

P = 1×3
104 ×

    8.9875    2.2632    0.5475

rho = 1×3

    1.1116    0.3639    0.0880

Input Arguments

height — Geopotential heights

m-by-n array

Geopotential heights, specified as an m-by-n array.

Data Types: double

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and enclose Name in quotes.

Example: extended,false implements the mathematical representation of the International Standard Atmosphere values for ambient temperature, pressure, density, speed of sound, and kinematic viscosity for the input geopotential altitude between the sea level and the tropopause.

extended — Range of implementation

false or 'off' (default) | true or 'on'

Mathematical representation between sea level and tropopause, specified as false or true. Set extended to false or to 'off' to implement the mathematical representation of the International Standard Atmosphere values for ambient temperature, pressure, density, speed of sound, and kinematic viscosity for the input geopotential altitude between the sea level and the tropopause.

Set extended to true or 'on' to implement the mathematical representation of the International Standard Atmosphere values for ambient temperature, pressure, density, speed of sound, and kinematic viscosity for the input geopotential altitude between -5000 meters and the mesopause.

action — Function behavior

'Warning' (default) | 'None' | 'Error'

Function behavior when input heights are out of range, specified as one of these values.

Value	Description
'None'	Does not display warning or error. If the input is less than the lower limit of the range, the output is set to the lower limit. If the input is greater than the upper limit of the range, the output is set to the upper limit.
'Warning'	Warning in the MATLAB® Command Window indicating that the input height is out of range.
'Error'	MATLAB displays error and indicates that the required input heights are out of range.

Dependencies

The atmosisa function takes the action into account when 'extended' is set to 'true'.

Output Arguments

T — Temperatures

m-by-n array

Temperatures, returned as an m-by-n array, in kelvin.

a — Speeds of sound

m-by-n array

Speeds of sound, returned as an m-by-n array, in meters per second. The function calculates speed of sound using a perfect gas relationship.

P — Pressures

m-by-n array

Pressures, returned as an m-by-n array, in pascal.

rho — Densities

m-by-n array

Densities, returned as an m-by-n array, in kilograms per meter cubed. The function calculates density using a perfect gas relationship.

nu — Kinematic viscosity

m-by-n array

Kinematic viscosity, returned as an m-by-n array, in m²/s.

mu — Dynamic viscosity

m-by-n array

Dynamic viscosity, returned as an m-by-n array, in kilograms per meter second.

Limitations

Set upper and lower limits for geopotential altitudes using the 'extended' name-value argument.

• If the 'extended' flag is set to 'false', the function clips the output values below the geopotential altitude of 0 meters and above the geopotential altitude of the tropopause at 20,000 meters.

• If the 'extended' flag is set to 'true', the function limits the implementation to the geopotential altitude of -5000 meters (minimum) and the mesopause at 84,852 meters (maximum).

If the action input is 'error', an input geopotential height outside these limits results in error. If the action input is 'warning' or 'none', the outputs are held at the limits.

References

[1] U.S. Standard Atmosphere, 1976. U.S. Government Printing Office, Washington, D.C.

Version History

Introduced in R2006b

R2024a: atmosisa function Changes

Use the new atmosphere function updates to return dynamic viscosity using the optional atmosisa function output.

R2023a: atmosisa Function Changes

The atmosisa function now supports the ISA atmosphere model input geopotential altitude between -5000 meters and the mesopause. In previous releases, atmosisa supported input geopotential altitudes between sea level and the tropopause.

To support the new capability, the function has these changes:

• extended name-value argument, which lets you specify:

  • false or 'off' — atmosisa supports input geopotential altitudes between the sea level and the tropopause.

  • true or 'on' — atmosisa supports input geopotential altitudes between -5000 meters and the mesopause.

• nu output, which returns a numeric array of M-by-N values of kinematic viscosities in m²/s.

• 'action' name-value argument, which lets you specify the action for out-of-range input when 'extended' is set to 'true'.