COMPARISON OF THE LEAST-SQUARES CRITERION AND THE CAUCHY CRITERION IN FREQUENCY-WAVE-NUMBER INVERSION

One alternative to the least-squares inversion technique is the use of a Cauchy error criterion. We show how inversion algorithms of the Gauss-Newton type based on the least-squares method can be modified to handle the Cauchy norm. A criterion for the lower bound of the scale parameter in the Cauchy norm is given. We compare the least-squares and Cauchy error criteria by inverting synthetic data corrupted by random noise and weather noise. The data are transformed to the frequency-wavenumber domain before the inversion starts. The numerical examples show that the algorithm based on the Cauchy criterion is more robust in the presence of the noise tested here. Per iteration, the computer costs of the two algorithms are approximately the same.