5.1.15. TEM data: GIF file

This file is used to specify the transmitters and associated data for a Time-domain ElectroMagnetic (TEM) survey. The file is broken down based on the transmitters and requires all data types be present (although they may be filled with an ignore value; see below). The convention is z+down and x+ East and y+ North. Comment lines begin with !. The data line contains 27 columns (x, y, z, E, H, and dB/dt data with uncertainties), but may be filled with ignore flags to denote using only certain data types. Below is the general format:

Parameter definitions:

• flg: Any string/value that does not contain actual data. By default, GIFtools will export NaN as the ignore value. The flag IGNORE preceeds this input.

• ntx: Number of transmitters. The flag N_TRX preceeds this input.

• TRX_FLAG: The \(i^{th}\) transmitter. This line contains the specific transmitter flag and block defining the transmitter. See GIF EM transmitters for specifications on formatting different transmitters.

• nRec: Number of receivers for the \(i^{th}\) transmitter. The flag N_RECV preceeds this input.

• nTime: The number of time channels for the \(j^{th}\) receiver associated with the \({i^{th}\) transmitter. The flag N_TIMES preceeds this input.

• \(X_{[i,j,k]}\): Easting (m) of the \(j^{th}\) receiver at the \(k^{th}\) time for the \(i^{th}\) transmitter.

• \(Y_{[i,j,k]}\): Northing (m) of the \(j^{th}\) receiver at the \(k^{th}\) time for the \(i^{th}\) transmitter.

• \(Z_{[i,j,k]}\): Elevation (m) of the \(j^{th}\) receiver at the \(k^{th}\) time for the \(i^{th}\) transmitter.

• \(Time\): Time (sec) of the observation.

• Edata: 6 columns containing electric-field data aligning with the cartesian coordinate system and their uncertainties \(j^{th}\) receiver at the \(k^{th}\) time for the \(i^{th}\) transmitter (in order):

  • \(Ex\): Electric-field component in the Easting direction.

  • \(Ex_{stn}\): Standard deviation of the electric-field component in the Easting direction. This must be a positive, non-zero number.

  • \(Ey\): Electric-field component in the Northing direction.

  • \(Ey_{stn}\): Standard deviation of the electric-field component in the Northing direction. This must be a positive, non-zero number.

  • \(Ez\): Vertical component of the electric-field.

  • \(Ez_{stn}\): Standard deviation of the vertical component of the electric-field. This must be a positive, non-zero number.

• Hdata: 6 columns containing magnetic-field data aligning with the cartesian coordinate system and their uncertainties \(j^{th}\) receiver at the \(k^{th}\) time for the \(i^{th}\) transmitter (in order):

  • \(Hx\): Magnetic-field component in the Easting direction.

  • \(Hx_{stn}\): Standard deviation of the magnetic-field component in the Easting direction. This must be a positive, non-zero number.

  • \(Hy\): Magnetic-field component in the Northing direction.

  • \(Hy_{stn}\): Standard deviation of the magnetic-field component in the Northing direction. This must be a positive, non-zero number.

  • \(Hz\): Vertical component of the magnetic-field.

  • \(Hz{stn}\): Standard deviation of the vertical component of the magnetic-field. This must be a positive, non-zero number.

• dBdTdata: 6 columns containing \(\partial B / \partial t\) data aligning with the cartesian coordinate system and their uncertainties \(j^{th}\) receiver at the \(k^{th}\) time for the \(i^{th}\) transmitter (in order):

  • \(\partial B / \partial t_x\): Derivative the B-field in the Easting direction.

  • \(\partial B / \partial t_x^{stn}\): Standard deviation of the derivative the B-field in the Easting direction. This must be a positive, non-zero number.

  • \(\partial B / \partial t_y\): Derivative the B-field in the Northing direction.

  • \(\partial B / \partial t_y^{stn}\): Standard deviation of the derivative the B-field in the Northing direction. This must be a positive, non-zero number.

  • \(\partial B / \partial t_z\): Vertical component of the derivative the B-field.

  • \(\partial B / \partial t_z^{stn}\): Standard deviation of the vertical component of the derivative the B-field. This must be a positive, non-zero number.

5.1.15.1. Examples

Example 1: The following is an example with 2 vertical magnetic dipole transmitters, each with 1 receiver recording at 19 time channels. Only the \(\partial B / \partial t_z\) data and its uncertainty are given:

Example 2:: The second example is from a UTEM survey. The large loop is given by 20 locations, has 2 receivers recording at 9 time channels. Only the \(\partial B / \partial t_z\) data and its uncertainty are given and some early times are not recorded and thus would be ignored: