Apply DC Shift in GM-SYS Profile Modelling

A constant or DC shift usually must be applied to the calculated gravity and/or magnetic data to match the observed data. For gravity, this is necessary because the calculated value is an absolute gravity calculation for the model extending to 30,000 km in the ±X and ±Y directions, and to some arbitrary depth (50 km by default). Observed data are generally corrected for the reference geoid, or referenced to some local datum. For the magnetic response, the calculated value is the deviation from the ambient earth field value, whereas another datum may have been used for the observed data.

In GM-SYS Profile Modelling, a DC Shift can be applied to the calculated curve to force the calculated curve and the observed curve to match.