“…Here the observations are radar measurements, the unknown parameters are those that describe the atmospheric refractivity, and the nonlinear function is the differential equation governing radio frequency wave propagation. Often, the search space is too vast Most inverse methods that have been applied to-date involve use of sea clutter data to inversely determine various aspects of the refractivity (Douvenot et al, 2010;Fountoulakis & Earls, 2016;Gerstoft et al, 2003Gerstoft et al, , 2004Karimian et al, 2013;Rogers et al, 2000Rogers et al, , 2005Yardim et al, 2009;Zhao et al, 2017;Zhau & Huang, 2012). One of the difficulties in using sea clutter to perform refractivity inversions is that backscatter from the sea surface is not completely understood (Ward et al, 1990); thus, determining the proper reflection coefficients for the prediction of backscatter is challenging and likely introduces error into the inversion process for those approaches that utilize a backscatter model.…”