How to plot Power spectral density vs. wavelength for a two dimensional data

I got a two dimensional spatial dataset. The data is a matrix of the size 50 X 50 with a distance of 100 km between data points. The task is to plot a curve of power spectral density versus wavelength. This topic is covered briefly in several geophysical articles for gravity and magnetic data interpretation, but it's never clear how can it be performed in a software. That's why I'm asking how is it possible to do it in Matlab, if it is possible at all? Thank you! Here I showed an example of the expected result.

[dpb]

How does the 2D come into the above plot?

I'm uncertain how one would take spatial data and define a wavelength from it...just what is the data at these points?

[Igor Ognev]

Hello!

The data represents a map of Bouguer gravity anomaly values. The wavelenght corresponds to the dimensions of anomalies on the map. It is certaintly possible and well described in the web how to plot radially averaged PSD vs. wavenumber:

1) It can be done either in Matlbab:

https://www.mathworks.com/matlabcentral/fileexchange/23636-radially-averaged-power-spectrum-of-2d-real-valued-matrix

2) Or Oasis Montaj's extention called MagMap.

But it is still unclear how to obtain the graph that I layed out here. Hope that math community will help us out with clarifing how to do that.

Thank you.

[dpb]

OK, so the 2D is smooshed into 1D; that explains the first Q? of what happened to the 2D data.

What's the problem, specifically, with plotting? Other than FFT transforms time into frequency and ergo distance into inverse distance (more precisely cycles/unit distance) so I guess the x-axis has been transformed into its inverse representation as well to be labelled in distance units it appears to be a very straightforward plotting exercise.

Is the plot from your data or some other paper? Reference if so such that somebody could try to reproduce? You could attach your dataset so somebody could at least try something with your data if were inclined.

[Bjorn Gustavsson]

Since, as dpb says, the wavelength is just the inverse of the wavenumber, you should be able to easily modify this sunspot example.