Transform from Magnetic Pole (TRFP)

Use the Transform from Magnetic Pole option to apply the transform-from-pole filter.

Transform from Magnetic Pole dialog options

Date (YYYY/MM/DD)	Enter the date when the survey was conducted to automatically calculate and populate the inclination and declination values. A Calculate button appears to the right of the date entry once a valid date is provided. This field is optional.
Inclination	Geomagnetic inclination I, in degrees measured from the horizon.
Declination	Geomagnetic declination D, in degrees azimuth.
Amplitude correction inclination	Amplitude correction inclination Ia, in degrees. Default values: +20° in the northern hemisphere –20° in the southern hemisphere

Application Notes

This filter is the mathematical inverse of the Reduction to the Pole (RTP) filter.

The amplitude correction is not strictly required, but it is retained to ensure exact recovery of the original grid. Refer to Reduce to Magnetic Pole (REDP) for additional details.

This filter is also a valuable educational tool for visualizing how magnetic anomalies would appear under different combinations of inclination and declination.

Reduction to Magnetic Pole Filter

Where:

I	Geomagnetic inclination (°).
D	Geomagnetic declination (° azimuth).
Ia	Inclination for amplitude correction (never less than I). Default = ±20°. If | Ia | is entered as less than | I |, it is set to I.

Wavenumber Domain Variable Definitions

The following variables are used in the wavenumber domain:
k	Wavenumber increment, used to depict a radially symmetrical variable.	Where: np: number of points cs: cell size
μ	X-component of the wavenumber.
v	Y-component of the wavenumber.
r	Radial component of the wavenumber.
θ	Angular (polar) component of the wavenumber.