1. Select the Axis in the Contents window.
2. In the Properties window, click the Scaling tab.
3. Check the box in the Reverse axis field.

Surfer does not currently offer the ability to reverse the direction of a Z axis.  However, you can multiply the grid Z values by -1. To do this:

1. Click Grids | Calculate | Math. This opens the Grid Math dialog.
2. Click the Add Grids button, select the grid file, and click Open.
3. Enter A*-1 in the Enter a function... field.
4. Edit the Output Grid name and location as desired.
5. Determine whether to add the new grid to a new or existing map as a map layer.
6. Click OK.
7. If an Export Options dialog appears, choose the desired spatial reference file(s) to export, and click OK.
8. Click OK in the dialog telling you your new grid file has been created.

 If you would like to see the ability to reverse Z axes in Surfer, please let us know by emailing surfersupport@goldensoftware.com.

Updated November 1, 2021