I have used the skimage find_contours on some velocity data but I am struggling to work out how to replot the contour outline onto a longitude latitude grid ?

I think it is some sort of transform in coordinates but I am struggling to work out how.
I have used the skimage find_contours on some velocity data but I am struggling to work out how to replot the contour outline onto a longitude latitude grid ?

I think it is some sort of transform in coordinates but I am struggling to work out how.