Generating contour plot from two sets of XY pairs

I have two sets of XY data, representing distance and intensity, and I wish to add the intensities to make an XYZ contour plot.

This is the way I've been thinking about it: I have a 2D plot of intensity vs distance on the x-axis, which I would like to propagate along the orthogonal y-axis, so that I end up with a sort of "tunnel" along the y-axis. Then, I also have a 2D plot of intensity vs distance on the y-axis, which I would like to propagate along the x-axis in the same fashion as before. I would like the z-components of each data set to add to a new z value at each xy data point, to give me the composite 3D surface.

I have been trying to figure out how to do this by creating 3D waves by concatenation, but in the matrix addition operation, I only want the z components to sum.

If someone could point me in the right direction for those propagation steps, I think the matrix addition would work out, and give me a composite 3D matrix from which I could generate a contour plot.

As always, many thanks for your advice!

-Kevin