Aerospace Toolbox

atmosnonstd - Use climatic data from MIL-STD-210 or MIL-HDBK-310

Syntax

[T, a, P, rho] = atmosnonstd(h, atype, extreme, freq, extalt, action, spec)

Description

[T, a, P, rho] = atmosnonstd(h, atype, extreme, freq, extalt, action, spec) implements a portion of the climatic data of the MIL-STD-210C or MIL-HDBK-310 worldwide air environment to 80 km geometric (or approximately 262,000 feet geometric) for absolute temperature, pressure, density, and speed of sound for the input geopotential altitude.

Inputs for atmosnonstd are:

`h`	An array of `m` geopotential heights, in meters
`atype`	A string selecting the representation of `'Profile'` or `'Envelope'` for the atmospheric data. `'Profile'` is the realistic atmospheric profiles associated with extremes at specified altitudes. `'Profile'` is recommended for simulation of vehicles vertically traversing the atmosphere, or when the total influence of the atmosphere is needed. `'Envelope'` uses extreme atmospheric values at each altitude. `'Envelope'` is recommended for vehicles traversing the atmosphere horizontally, without much change in altitude.
`extreme`	A string selecting the atmospheric parameter which is the extreme value. Atmospheric parameters that can be specified are `'High temperature'`, `'Low temperature'`, `'High density'`, `'Low density'`, `'High pressure'` and `'Low pressure'`. `'High pressure'` and `'Low pressure'` are available only when `atype` is `'Envelope'`.
`freq`	A string selecting percent of time the extreme values would occur. Valid values for `freq` include `'Extreme values'`, `'1%'`, `'5%'`, `'10%`', and `'20%'`. `'Extreme values'`, `'5%'`, and `'20%'` are available only when `atype` is `'Envelope'`. When using `atype` of `'Envelope'` and `freq` of `'5%'`, `'10%`', and `'20%'`, only the `extreme` parameter selected (temperature, density, or pressure) has a valid output. All other parameter outputs are zero.
`extalt`	A scalar value, in kilometers, selecting geometric altitude at which the extreme values occur. `extalt` applies only when `atype` is `'Profile'`. Valid values for `extalt` include `5` (16404 ft), `10` (32808 ft), `20` (65617 ft), `30` (98425 ft), and `40` (131234 ft).
`action`	A string to determine action for out-of-range input. Specify if out-of-range input invokes a `'Warning'`, `'Error'`, or no action (`'None'`). The default is `'Warning'`.
`spec`	A string specifying the atmosphere model, MIL-STD-210C or MIL-HDBK-310: `'210c'` or `'310'`. The default is `'310'`.

Outputs calculated for the lapse rate atmosphere are:

`T`	An array of `m` temperatures, in kelvin
`a`	An array of `m` speeds of sound, in meters per second
`P`	An array of `m` air pressures, in pascal
`rho`	An array of `m` air densities, in kilograms per meter cubed

Examples

Calculate the nonstandard atmosphere profile with high density occurring 1% of the time at 5 kilometers from MIL-HDBK-310 at 1000 meters with warnings for out-of-range inputs:

[T, a, P, rho] = atmosnonstd( 1000,'Profile','High density','1%',5 )


T =

  248.1455


a =

  315.7900


P =

  8.9893e+004


rho =

    1.2620

Calculate the nonstandard atmosphere envelope with high pressure occurring 20% of the time from MIL-STD-210C at 1000, 11,000, and 20,000 meters with errors for out-of-range inputs:

[T, a, P, rho] = atmosnonstd([1000 11000 20000],'Envelope', ...
                              'High pressure','20%','Error','210c' )



T =

  0     0     0


a =

  0     0     0


P =

  1.0e+004 *
    9.1598    2.5309    0.6129


rho =

    0     0     0

Assumptions and Limitations

All values are held below the geometric altitude of 0 m (0 feet) and above the geometric altitude of 80,000 meters (approximately 262,000 feet). The envelope atmospheric model has a few exceptions where values are held below the geometric altitude of 1 kilometer (approximately 3281 feet) and above the geometric altitude of 30,000 meters (approximately 98,425 feet). These exceptions are due to lack of data in MIL-STD-210 or MIL-HDBK-310 for these conditions.

In general, temperature values are interpolated linearly and density values are interpolated logarithmically. Pressure and speed of sound are calculated using a perfect gas relationship. The envelope atmospheric model has a few exceptions where the extreme value is the only value provided as an output. Pressure in these cases is interpolated logarithmically. These envelope atmospheric model exceptions apply to all cases of high and low pressure, high and low temperature, and high and low density, excluding the extreme values and 1% frequency of occurrence. These exceptions are due to lack of data in MIL-STD-210 or MIL-HDBK-310 for these conditions.

A limitation is that climatic data for the region south of 60 degrees S latitude is excluded from consideration in MIL-STD-210 or MIL-HDBK-310.

This function uses the metric version of data from the MIL-STD-210 or MIL-HDBK-310 specifications. A limitation of this is some inconsistent data between the metric and English data. Locations where these inconsistencies occur are within the envelope data for low density, low temperature, high temperature, low pressure, and high pressure. The most noticeable differences occur in the following values:

For low density envelope data with 5% frequency, the density values in metric units are inconsistent at 4 km and 18 km and the density values in English units are inconsistent at 14 km.
For low density envelope data with 10% frequency, the density values in metric units are inconsistent at 18 km and the density values in English units are inconsistent at 14 km.
For low density envelope data with 20% frequency, the density values in English units are inconsistent at 14 km.
For high pressure envelope data with 10% frequency, the pressure values at 8 km are inconsistent.

References

Global Climatic Data for Developing Military Products (MIL-STD-210C), 9 January 1987, Department of Defense, Washington, D.C.