Response to
"Comment on 'The Hdroacoustics of a Raindrop Impact'
by H.C. Pumphrey"

Jeffrey A. Nystuen

Cooperative Institute for Marine and Atmospheric Studies
Rosenstiel School of Marine and Atmospheric Sciences
University of Miami
Miami, Florida

Abstract: Two components of the underwater pressure signal of a raindrop impact are identified. An initial single cycle impulse lasting less than 0.1ms is attributed to an acoustic "water hammer" of the raindrop onto the water surface. The second feature, a "plateau" pressure signal with a time scale over 1 ms, is associated with the nearly incompressible hydrodynamic flow of the drop splash. The radiated sound field from the impacts is dominated by the impulse component and produces a broad spectral peak near 15-20 kHz as previously reported.

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search issues. The relationship between equivalent reflectivity and rainfall rate, the Z-R diagram, is partitioned acoustically showing that parts of this diagram are occupied by rainfall containing specific drop populations. Rainfall type can be classified acoustically. And because of its relatively large catchment area, high temporal resolution analysis of rainfall is possible. This technique has inherent application in remote oceanic regions where measurements of rainfall are needed to help establish knowledge of the global distribution and intensity of rainfall.