Conclusions

• The intensity of a 200 kHz signal decreased during a large storm.

• But - subsequent structural failure raises questions of alignment, path obstruction, etc.

• Ascribing the attenuation to Rayleigh scattering by sand particles requires M*d^3 = (30 g/l)*(200 microns)^3 - unrealistic.

• Strong interference between direct and surface-reflected ray complicates coherent detection for measuring time delays.