4.1.5.2. MT Data Manipulation Menu

4.1.5.2.1. Rotate impedance tensors

This functionality is used to rotate the impedance tensor in the case that the primary direction (X) does not lie along the Northing. This functionality can be accessed through:

• Data manipulation → Calculate → Rotate impedance tensor

The user will enter the amount of degrees clockwise they would like to rotate the impedance tensor data. For example, let us assume the data are defined such that X is towards the Northwest and Y is towards the Northeast. If we enter a value of 45, the impedance tensor data will be rotated to UBC-GIF convention (X = Northing and Y = Easting); assume that Z is +ve downward.

4.1.5.2.2. Convert between impedance data and apparent resistivity and phase data

This functionality either:

• generates apparent resistivity and phase data from impedance data, or

• generates impedance data from apparent resistivity and phase data

This functionality can be accessed through:

• Data manipulation → Create new item → Convert to apparent resistivity and phase data (APPdata)

• Data manipulation → Create new item → Convert to impedance data (IMPdata)

Some things to note about this functionality:

• A new data object is created when this functionality is used

• To compute \(\rho_{xy}\) and \(\phi_{xy}\) from Re[ \(\! Z_{xy} \!\) ] and Im[ \(\! Z_{xy} \!\) ], you must set the associated data headers. Some goes for the reverse operation.

• This functionality works regardless of whether data use a time-dependency of \(e^{i\omega t}\) or \(e^{-i\omega t}\).