Amplitudes are used to constrain refraction models. This study demonstrates that the refraction time section generated through the convolution of forward and reverse refraction traces together with a static shift facilitates the convenient recognition of amplitude variations related to changes in refractor wavespeed.
For large contrasts in wavespeeds between the upper layer and the refractor, the head coefficient is approximately proportional to the ratio of the specific acoustic impedances. Since the convolution operation effectively multiplies the amplitudes of the forward and reverse arrivals, the convolved amplitudes are proportional to the square of this ratio. In general, the higher the contrast in the refractor wavespeed and/or density, the lower the amplitude. The regions recognized in the wavespeed analysis function correlate with those determined with amplitudes, thereby providing an additional constraint on inversion with model-based approaches.