5. Appendix: effect of GN

The power associated with each pixel of \(I_{GN}\) can be expressed as [RD4]:

(1)\[\begin{equation} |I_{GN}(r,a)|^2 = 2 \int \sigma(r,a,z)^2 [1 - \cos(k_z(r,a)\, z)]\, dz \tag{5.1} \end{equation}\]

where \(\sigma(r,a,z)^2\) is uncorrelated reflectivity density along \(z\), and \(k_z(r,a) = k_z(r,a,1) - k_z(r,a,2)\) is the interferometric pair vertical wavenumber.