harmonica.total_field_anomaly

harmonica.total_field_anomaly(magnetic_field, inclination, declination)

The total field anomaly from the anomalous magnetic field.

Compute the total field anomaly from the anomalous magnetic field given the regional field direction.

Note

Inclination is measured positive downward from the horizontal plane and declination is measured with respect to North and it is positive east.

Parameters:

magnetic_fieldtuple of floats or tuple of arrays

Three component vector of the anomalous magnetic field.

inclinationfloat or array

Inclination angle of the regional field. It must be in degrees.

declinationfloat or array

Declination angle of the regional field. It must be in degrees.

Returns:

total_field_anomalyfloat or array

The magnetic total field anomaly in the same units as the magnetic_field.

Notes

Given the magnetic field, \(\mathbf{B}\), the regional field, \(\mathbf{F}\), the total field anomaly can be computed as:

\[\Delta T = \mathbf{B} \cdot \mathbf{\hat{F}}\]

where \(\mathbf{\hat{F}}\) is the unit vector in the same direction as the regional field.

Examples

>>> tfa = total_field_anomaly([0, 0, -50e3], 90.0, 0.0)
>>> print(tfa)
50000.0