Seasonal temperature gradients within a sandy seafloor: implications for acoustic propagation and scattering

Seafloor temperatures measured during the SAX99 experiment off Fort Walton Beach, Florida, included sharp decreases in response to the passage of cold fronts. Sediment pore water temperatures exhibited an increasing temperature (3-4o Cm) with depth in the sediment. By fitting a heat conduction model to the gradient data, the thermal diffusivity of the sediment was estimated to be 0.006 cms. The effects of seasonal variations of sediment thermal gradients on reflection and scattering from the sediment-water interface are found to be significant at frequencies near 1 kHz but diminish at higher frequencies.