Research Issues on ICGEM (EIGEN-6C4)

Hello Everyone,
I have a question to ask about ICGEM gravity data set, I have downloaded the EIGEN-6C4 from the ICGEM website, however, the data end with the suffix .gfc which cannot be read when I tried to use GMT, am question is how can I extract the data set and convert it to regular grid set that can be read by GMT. e.g. *.grd and not *.gfc

You must start by telling us what is a .gfc data set. If it happens to be a set of spherical harmonics coefficients, then no, GMT has no means of calculating a grid out of them.

yes it is a set of spherical harmonics coefficients

On the ICGEM site, there is a calculator option to allow you to extract the data for a particular region (or globally) at different resolutions. The result is in XYZ (with a header), might be a simpler route although I think you are limited to 300,000 data points depending on the area/resolution selected.

many thanks got it. @Prof. Joaquim @arctica

Well, sph2grd is supposed to do that calculation.

I tried once, probably for the same purpose, and it had lot’s of issues. Don’t remember details, only that I gave up.