# atmositu

Use ITU reference atmospheres

## Syntax

``[T,P,wvden] = atmositu(h)``
``[T,P,wvden] = atmositu(___,Name,Value)``
``atmositu(___)``

## 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`, 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, 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 scaleAtmospheric pressure `P` versus altitude in logarithmic x-scaleAtmospheric 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. `ScaleHeight`applies 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
`atmositu`hectoPascals (hPa)kelvin (K)
`tropopl`hectoPascals (hPa)kelvin (K)
`gaspl`Pascals (Pa)Celsius (C)

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

Atmospheric 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