polarMotion

Calculate Earth polar motion

Syntax

polarmotion = polarMotion(utc)

[polarmotion,polarmotionError] = polarMotion(utc)

polarmotion = polarMotion(utc,Name,Value)

[polarmotion,polarmotionError] = polarMotion(utc,Name,Value)

Description

polarmotion = polarMotion(utc) calculates the movement of the rotation axis with respect to the crust of the Earth for a specific Coordinated Universal Time (UTC), specified as a modified Julian date. By default, this function uses a prepopulated list of IAU 2000A Earth orientation (IERS) data. This list contains measured and calculated (predicted) data supplied by the IERS. The IERS measures and calculates this data for a set of predetermined dates.

[polarmotion,polarmotionError] = polarMotion(utc) calculates the error for the movement of the rotation axis with respect to the crust of the Earth.

polarmotion = polarMotion(utc,Name,Value) calculates the movement of the rotation axis with respect to the crust of the Earth using additional options specified by one or more Name,Value pair arguments.

[polarmotion,polarmotionError] = polarMotion(utc,Name,Value) calculates the error for the movement of the rotation axis with respect to the crust of the Earth.

Examples

Calculate Polar Motion

This example shows how to calculate the polar motion for December 28, 2015.

mjd = mjuliandate(2015,12,28)

mjd = 
57384

polarmotion = polarMotion(mjd)

polarmotion = 1×2
10-5 ×

    0.0289    0.1233

Calculate Polar Motion and Error Using IERS Data

Calculate the polar motion and polar motion error for December 28, 2015 and January 10, 2016 using the aeroiersdata.mat file. Use the mjuliandate function to calculate the date as a modified Julian date.

mjd = mjuliandate([2015 12 28;2016 1 10])
[polarmotion,polarmotionErr] = polarMotion(mjd,'Source','aeroiersdata.mat')

mjd =
       57384
       57397

polarmotion =
   1.0e-05 *
    0.0289    0.1233
    0.0174    0.1304

Input Arguments

utc — Coordinated Universal Time

M-by-1 array

Array of UTC dates, specified as an M-by-1 array, represented as modified Julian dates. Use the mjuliandate function to convert the UTC date to a modified Julian date.

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: 'Source','aeroiersdata.mat'

Source — Custom list of Earth orientation data

aeroiersdata.mat (default) | MAT-file

Custom list of Earth orientation data, specified in a MAT-file.

action — Out-of-range action

Warning (default) | action

Out-of-range action, specified as a string.

Action to take in case of out-of-range or predicted value dates, specified as a string:

• Warning — Displays warning and indicates that the dates were out-of-range or predicted values.

• Error — Displays error and indicates that the dates were out-of-range or predicted values.

• None — Does not display warning or error.

Data Types: string

Output Arguments

polarmotion — Movement of the rotation axis with respect to the crust of the Earth

M-by-2 array

Movement of the rotation axis with respect to the crust of the Earth, M-by-2 array, in radians.

polarmotionError — Error for movement of the rotation axis with respect to the crust of the Earth

M-by-2 array

Error for movement of the rotation axis with respect to the crust of the Earth, specified as an M-by-2 array, in radians.

Version History

Introduced in R2018b

R2020b: Updated aeroiersdata.mat file

The contents of the aeroiersdata.mat file have been updated. Correspondingly, the output of this function will have different results when using the default value ('aeroiersdata.mat') as the value of Source. The results reflect more accurate external data from the International Earth Rotation and Reference Systems Service (IERS).