atmosnonstd

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

Syntax

[T, a, P, rho] = atmosnonstd(height, atmosphericType, extremeParameter, frequency, extremeAltitude, action, specification)

Description

[T, a, P, rho] = atmosnonstd(height, atmosphericType, extremeParameter, frequency, extremeAltitude, action, specification) 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). This implementation provides absolute temperature, pressure, density, and speed of sound for the input geopotential altitude.

This function holds all values below the geometric altitude of 0 m (0 feet) and above the geometric altitude of 80,000 m (approximately 262,000 feet). The envelope atmospheric model has exceptions where values are held below the geometric altitude of 1 km (approximately 3281 feet). It also has exceptions above the geometric altitude of 30,000 m (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, this function interpolates temperature values linearly and density values logarithmically. It calculates pressure and speed of sound using a perfect gas relationship. The envelope atmospheric model has exceptions where the extreme value is the only value provided as an output. In these cases, the function interpolates pressure logarithmically. These envelope atmospheric model exceptions apply to all cases of high and low pressure, high and low temperature, and high and low density. These exceptions exclude 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 MIL-STD-210 and MIL-HDBK-310 exclude from consideration climatic data for the region south of 60 degrees S latitude.

This function uses the metric version of data from the MIL-STD-210 or MIL-HDBK-310 specifications. A limitation 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. In addition, 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. In addition, 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.

Input Arguments

height

Array of m-by-1 geopotential heights, in meters.

atmosphericType

Representation of 'Profile' or 'Envelope' for the atmospheric data:

`'Profile'`	Is the realistic atmospheric profiles associated with extremes at specified altitudes. Use `'Profile'` for simulation of vehicles vertically traversing the atmosphere, or when you need the total influence of the atmosphere.
`'Envelope'`	Uses extreme atmospheric values at each altitude. Use `'Envelope'` for vehicles traversing the atmosphere horizontally, without much change in altitude.

extremeParameter

Atmospheric parameter that is the extreme value. Atmospheric parameters that you can specify are:

'High temperature'

'Low temperature'

'High density'

'Low density'

'High pressure', available only if atmosphericType is 'Envelope'

'Low pressure', available only if atmosphericType is 'Envelope'

frequency

Percent of time that extreme values would occur. When using atmosphericType of 'Envelope' and frequency of '5%', '10%', and '20%', only the extreme* parameter that you specify (temperature, density, or pressure) has a valid output. All other parameter outputs are zero.

'Extreme values', available only if atmosphericType is 'Envelope'

'1%'

'5%', available only if atmosphericType is 'Envelope'

'10%

'20%', available only if atmosphericType is 'Envelope'

extremeAltitude

Scalar value, in kilometers, selecting geometric altitude at which the extreme values occur. extremeAltitude applies only when atmosphericType is 'Profile'.

`5`	16404 ft
`10`	32808 ft
`20`	65617 ft
`30`	98425 ft
`40`	131234 ft

action

Action for out-of-range input:

'Error'

'Warning' (default)

'None'

specification

Atmosphere model:

`'210c'`	MIL-STD-210C
`'310'`	MIL-HDBK-310 (default)

Output Arguments

`T`	Array of `m`-by-1 temperatures, in kelvin. This function interpolates temperature values linearly.
`a`	Array of `m`-by-1 speeds of sound, in meters per second. This function calculates speed of sound using a perfect gas relationship.
`P`	Array of `m`-by-1 pressures, in pascal. This function calculates pressure using a perfect gas relationship.
`rho`	Array of `m`-by-1 densities, in kilograms per meter cubed. This function interpolates density values logarithmically.

Examples

Calculate the nonstandard atmosphere profile. Use high density occurring 1% of the time at 5 km from MIL-HDBK-310 at 1000 m 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. Assume that high pressure occurs 20% of the time from MIL-STD-210C at 1000, 11,000, and 20,000 m 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