# atmositu

Use ITU reference atmospheres

Since R2021a

## Description

example

[T,P,wvden] = atmositu(h) calculates the International Telecommunication Union (ITU) standard atmospheric model known as the Mean Annual Global Reference Atmosphere (MAGRA) and returns the atmospheric temperature T, dry air pressure P, and water-vapor density wvden. MAGRA approximates the U.S. Standard Atmosphere 1976 with insignificant relative error.

example

[T,P,wvden] = atmositu(___,Name,Value) returns the atmospheric temperature, dry air pressure, and water-vapor density with additional options specified by one or more name-value pairs. For example, 'LatitudeModel','High' specifies a reference model for latitudes greater than 45°.

example

atmositu(___) with no output arguments plots:

• Atmospheric temperature T versus altitude in linear scale

• Atmospheric pressure P versus altitude in logarithmic x-scale

• Atmospheric water-vapor density wvden versus altitude in logarithmic x-scale

## Examples

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Compute the atmospheric temperature, pressure, and water vapor density at a height of 5 km at high latitudes in summer. Use default parameters.

h = 5e3;
[T,P,wvden] = atmositu(h)
T = 255.6755

P = 540.4828

wvden = 0.6156

Compute the atmospheric temperature, pressure, and water-vapor density for a mid-latitude area during winter. Specify an altitude range between 2 km and 88 km.

h = (2:88).*1e3;

[T,P,wvden] = atmositu(h,'LatitudeModel','Mid','Season','Winter');

Display the first 6 values of temperature, pressure, and water vapor density.

disp([T(1:6)',P(1:6)',wvden(1:6)'])
264.7771  789.5947    1.7601
260.2759  689.4528    1.1320
255.4229  598.9723    0.6829
250.2181  518.1532    0.3875
244.6615  446.9955    0.2074
238.7531  385.4992    0.1049

Plot the atmospheric temperature, pressure, and water-vapor density profiles for the same model.

atmositu(h,'Latitude','Mid','Season','Winter')

## Input Arguments

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Geometric heights corresponding to the altitude above mean sea level (MSL), specified as a row vector. The atmositu function returns NaN's for any input value outside of the interval [0,100000]. Units are in meters.

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: atmositu(h,'LatitudeModel','Mid','Season','Winter') specifies the mid-latitude model during winter.

Standard ground-level water-vapor density in g/m3, specified as a scalar. VaporDensity applies only when LatitudeModel is set to the default 'Standard' model.

Data Types: double

Scale height in meters, specified as a scalar. ScaleHeightapplies only when LatitudeModel is set to the default 'Standard' model. For a dry atmosphere, set ScaleHeight to 6000.

Data Types: double

Reference latitude model, specified as:

• 'Standard' — This is the Mean Annual Global Reference Atmosphere (MAGRA) model that reflects the mean annual temperature and pressure averaged across the world.

• 'Low' — Use this model for latitudes lower than 22°, with little seasonal variation.

• 'Mid' — Use this model for latitudes between 22° and 45° that have seasonal profiles for summer and winter. You can specify a seasonal profile using the Season name-value pair.

• 'High' — Use this model for latitudes greater than 45° that have seasonal profiles for summer and winter. You can specify a seasonal profile using the Season name-value pair.

Seasonal profile, specified as 'Summer' or 'Winter'. This argument is valid only when LatitudeModel is set to 'Mid' or 'High'.

## Output Arguments

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Atmospheric temperature in Kelvin, returned as an M-length row vector.

Note

The atmositu, gaspl, and tropopl functions use different units for pressure and temperature.

Pressure and Temperature Units

FunctionPressure UnitsTemperature Units
atmosituhectoPascals (hPa)kelvin (K)
tropoplhectoPascals (hPa)kelvin (K)
gasplPascals (Pa)Celsius (C)

One hPa equals 100 Pa and K = C + 273.15. Use caution when combining the use of these three functions.

Atmospheric dry air pressure in hectoPascals, returned as an M-length row vector.

Atmospheric water-vapor density in g/m3, returned as an M-length row vector.

## References

[1] International Telecommunication Union (ITU). "Reference Standard Atmospheres". Recommendation ITU-R P.835-6, P Series, Radiowave Propagation, December 2017.

## Version History

Introduced in R2021a