Precipitation in the Canadian Atlantic storms program: Measurements of the acoustic signature

Abstract

The Canadian Atlantic Storms Program (CASP) provided an opportunity for comparing two quite different remote‐sensing approaches to the detection of precipitation: radar backscatter and ambient ocean sound. Several of the gales passing the observation area during CASP produced substantial precipitation with the periods of radar backscatter showing close coincidence with simultaneous acoustic signals. The ambient sound record most readily yields an indication of precipitation from shifts in spectral slope. An important result of the experiment is the demonstration that an identifiable precipitation signal occurs even in strong wind conditions. The surface bubble layer formed during strong winds only partially attenuates the higher frequency acoustic components generated by precipitation. During rain‐free periods the attenuation can be interpreted in terms of the bubble size distribution.