atmoshwm

Implement horizontal wind model

Syntax

wind = atmoshwm(latitude,longitude,altitude)

wind = atmoshwm(latitude,longitude,altitude,Name,Value)

Description

wind = atmoshwm(latitude,longitude,altitude) implements the U.S. Naval Research Laboratory Horizontal Wind Model (HWM™) routine to calculate the meridional and zonal components of the wind for one or more sets of geographic coordinates: latitude, longitude, and altitude.

wind = atmoshwm(latitude,longitude,altitude,Name,Value) uses additional options specified by one or more Name,Value pair arguments.

Examples

Calculate the Total Horizontal Wind Model

This example shows how to calculate the total horizontal wind model for a latitude of 45 degrees south, longitude of 85 degrees west, and altitude of 25,000 m above mean sea level (msl). The date is the 150th day of the year, at 11 am UTC, using an Ap index of 80. The horizontal model version is 14.

w = atmoshwm(-45,-85,25000,'day',150,'seconds',39600,'apindex',80,'model','total', 'version', '14')

w = 1×2

    3.2874   25.8735

Calculate the Quiet Horizontal Wind Model

Calculate the quiet horizontal wind model for a latitude of 50 degrees north, two altitudes of 100,000 m and 150,000 m above msl, and a longitude of 20 degrees west. The date is midnight UTC of January 30. The default horizontal model version is 14.

w = atmoshwm([50;50],[-20;-20],[100000;150000],'day',[30;30])

w = 2×2

  -42.9350  -40.3693
   29.1106    0.6253

Calculate a Disturbed Horizontal Wind Model

Calculate the disturbed horizontal wind model for an altitude of 150,000 m above msl at latitude 70 degrees north, longitude 65 degrees west. The date is midnight UTC of June 15. The default horizontal model version is 14.

dw = atmoshwm(70,-65,150000,'day',166,'model','disturbance')

dw = 1×2

    1.7954   -1.7130

Input Arguments

latitude — Geodetic latitude

scalar | M-by-1 array

Geodetic latitudes, in degrees, specified as a scalar or M-by-1 array.

Example: -45

Data Types: double

longitude — Geodetic longitude

scalar | M-by-1 array

Geodetic longitudes, in degrees, specified as a scalar or M-by-1 array.

Example: -85

Data Types: double

altitude — Geopotential height

scalar | M-by-1 array

Geopotential heights, in meters, within the range of 0 to 500 km, specified as a scalar or M-by-1 array. Values are held outside the range 0 to 500 km.

Example: 25000

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: 'apindex',80,'model','total' specifies that the total horizontal wind model be calculated for an Ap index of 80.

apindex — Ap index

M-by-1 array of zeroes (default) | scalar | M-by-1 array

Ap index for the Coordinated Universal Time (UTC) at which atmoshwm evaluates the model, specified as an M-by-1 array of zeroes, a scalar, or an M-by-1 array. M is the number of requested geographic coordinates. Select the index from the NOAA National Geophysical Data Center, which contains three-hour interval geomagnetic disturbance index values. If the Ap index value is greater than zero, the model evaluation accounts for magnetic effects.

Specify the Ap index as a value from 0 through 400. Specify an Ap index value for only the disturbance or total wind model type.

Data Types: double

day — Day of year

M-by-1 array of ones (default) | scalar | M-by-1 array

Day of year in UTC. Specify the day as a value from 1 through 366 (for a leap year), specified as an M-by-1 array of zeroes, a scalar, or an M-by-1 array. Values are wrapped to within 1 to 366 days.

Data Types: double

seconds — Elapsed seconds

M-by-1 array of zeroes (default) | scalar | M-by-1 array

Elapsed seconds since midnight for the selected day, in UTC, specified as specified as an M-by-1 array of zeroes, a scalar, or an M-by-1 array.

Specify the seconds as a value from 0 through 86,400. Values are wrapped to within 0 to 86400 seconds.

Data Types: double

model — Horizontal wind model type

'quiet' (default) | 'disturbance' | 'total'

Horizontal wind model type for which to calculate the wind components. This setting applies to all the sets of geophysical data in M.

• 'quiet'

  Calculates the horizontal wind model without the magnetic disturbances. Quiet model types do not account for Ap index values. For this model type, do not specify an Ap index value.

• 'disturbance'

  Calculates the effect of only magnetic disturbances in the wind. For this model type, specify Ap index values greater than or equal to zero.

• 'total'

  Calculates the combined effect of the quiet and magnetic disturbances. for this model type, specify Ap index values greater than or equal to zero.

Data Types: char | string

action — Function behavior

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

Function behavior when inputs are out of range, specified as one of these values. This type applies to all the sets of geophysical data in M.

Value	Description
'None'	No action.
'Warning'	Warning in the MATLAB® Command Window, model simulation continues.
'Error'	MATLAB returns an exception, model simulation stops.

Data Types: char | string

version — Horizontal wind model version

'14' (default) | '07'

Implements specified horizontal wind model type.

• '14'

  Horizontal Wind Model 14.

• '07'

  Horizontal Wind Model 07.

Data Types: char | string

Output Arguments

wind — Meridional and zonal wind components

M-by-2 array

Meridional and zonal wind components of the horizontal wind model, returned as an M-by-2 array, in m/s.

Version History

Introduced in R2016b

R2021b: atmoshwm Function Possible Changed Returned Values

The atmoshwm function now:

• Accepts day decimal input values.

• Limits altitude input values to 500 km.

As a result, the output values from this function might change from previous releases.