Making measurements of surface weather conditions in oceanic regions is relatively
difficult, and yet these data are needed for many types of climatic and process
studies of air-sea interaction. Passive monitoring of the underwater sound field
offers a means to make these measurements, as several air-sea interaction processes
are responsible for the production and modification of underwater sound in the
ocean. In the frequency range from 500 Hertz to 50 kHz, natural sources of underwater
sound include breaking wind waves and precipitation. Unique characteristics of
these sound sources allow them to be identified and then quantified. Furthermore,
distortion of these acoustic signals by sub-surface ambient bubbles permits the
detection and quantification of the near-surface bubbles, a potential indication
of gas transfer and sea state conditions.
· Using
Ambient Sound to Passively Monitor Sea Surface Processes
(Keynote Paper: Pan Oceanic Remote Sensing
Conference (PORSEC 2002), Bali, Indonesia, September 2002)
· Listening to Raindrops (NASA
Earth Observatory Feature Story, June 2000)
o An
overview (Nystuen,
1999 - general overview talk from the John D. Nystuen Symposium, The University
of Michigan)
o An Acoustic Disdrometer
(Nystuen,
2001; Nystuen,
1996)
o Classification of Rainfall
(Nystuen
and Amitai, 2002)
· Acoustic
Rain Gauges (ARGs)
· ARGs on deep ocean moorings
o Acoustic Log from the South China Sea (Nystuen,
McPhaden and Freitag, 1990)
o Tropical Atmosphere
Ocean (TAO) array (http://www.pmel.noaa.gov/tao/)
o Acoustic Measurements of Precipitation
from Deep Ocean Mooring (Poster
from AGU Spring Meeting 2002)
· The latest results
o Comparing
ARG, RMY and TRMM rainfall estimates
