How to create smooth and stable waves using MagFields?

Hi, I'm trying to replicate the effect show in this image:

I've created a field of points and then manipulated their z-movement based on the strength of the mag-field at those points. However, the center of each "wave" is not smooth or consistent, like here:

I've tried bumping the DPI of the underlying grid thinking it was a problem with that, but it just makes the problem more acute. The other option I have considered is cutting the centers out and re-modeling them separately, either by hand or a different definition, but that would be my absolutely last resort.

I'm attaching my definition, and any help you guys can give me would be greatly appreciated.