Using interp2 on maps that have different longitude systems

Hello,

I am trying to use interp2 between A and B

A longitude spans 0 to 360

B longitude spans -180 to 180

If I use wrapTo180 on A, it is no longer monotonically increasing.

If I use wrapTo360 on B, it is no longer monotonically increasing.

If I use interp2 without wrapping either, I only get the interpolated data for longitudes 0+

What are my options for getting a full global interpolation with these different longitude systems?

Thank you,

Melissa

[Stephen23]

@Melissa: you have asked versions of this question several times, and received good explanations:

http://www.mathworks.com/matlabcentral/answers/216788-interpolation-problem-between-two-2d-global-datasets

http://www.mathworks.com/matlabcentral/answers/216909-using-interp2-on-maps-that-have-different-longitude-systems

http://www.mathworks.com/matlabcentral/answers/216774-find-nearest-grid-cell-between-two-2d-matrixes-of-different-resolution

Usually the answer seems to be Walter Roberson saying "...unwrap one of them and circshift as needed...". Have you tried that?

Answer 1

[Walter Roberson]

unwrap one of them and circshift as needed to make it and the referenced data monotonically increasing.

Blongwrap = wrapTo360(Blong);
crossingidx = find(diff(Blongwrap) < 0, 1);
Blongwrapshifted = circshift(Blongwrap(:),-crossgidx,1);
Bshifted = circshift(B, -crossingidx, 1);

This assumes that, as per your previous postings, longitude varies in the first dimension.

[Melissa]

Thank you so much! Sorry, I didn't see your comments from the other posts because it doesn't notify me :(