(color online) The inversion results and comparisons with the observed data, where the left column compares the inverted refractivity profiles (red) with the helicopter observed profiles (blue), and the right column compares the inverted clutter strength (red) and helicopter-based profiles (blue) with the radar clutter strength (black). To eliminate the influence of the uncertainty value of σ on the helicopter-based clutter strength, all the clutter data were modified by subtracting each mean value.