🚀 go-pugleaf

In <egeisler.764383985@qualcom>, egeisler@qualcomm.com (Eric Geisler) writes:
[Data from Weilgart and Whitehead posts previous.......]
>
>I am quite concerned that the following issue has not received the
>necessary publicity to lend itself to healthy dialog about this matter.
>I am referring to two extremely loud sound sources that are starting
>operation this month and next month, off 1) Kauai, Hawaii and 2) Pt. Sur,
>California, which is an especially productive area rich in marine mammal
>life.  The speakers are to be placed at a depth of about 700-800 m just off
>the coast of these two locations.  The intensity of these sound sources will
>be about 195 dB.  This is about 10,000,000 times 120 dB (dB is a logarithmic
>scale).  120 dB is the level of intensity at which even the comparatively
>acoustically insensitive grey whale avoids noise.  120 dB is also the threshold
>of pain for humans for airborne sound.

Do the authors have a problem with the vocalizations of blue, humpback,
minke and finback whales?  These inconsiderate species make calls with
source levels of 180 to 190 dB, and might also be disturbing grey whales.

120 dB is the threshold of *feeling* for humans and airborne sound, 140 dB
(or 100 times that level) is the threshold of pain.  That doesn't begin
to tell the story though.  The *reference levels* for underwater and
airborne sound are different.  For underwater sound, the conventional
reference is the micropascal, or 0.67E-18 watts per square meter.  For
airborne sound the reference LsubI (ISO standard) is 1.0E-12 watts per
square meter.  It is an egregious error at best, and deceptive at worst,
to compare sound levels in air and water without taking into account
the difference in reference levels (61 dB has to be added to the air
levels to convert to the same reference used in underwater sound).

[some material deleted]

>Many climatologists question whether ATOC
>is the best way to gauge global warming, especially as the source is located
>so far (800 m) below the ocean surface.

While the source is 800 meters below the ocean surface, the sound it
transmits "illuminates" the ocean from near the surface to the bottom
along the paths.  The measurements of travel times, and the subsequent
inversion to temperature, consider multiple acoustic paths and full
range of depths the sound traverses.  The temperature estimate provided
by this technique is an *AVERAGE* for the ocean along the path.  This
is precisely the type of measurement that is required to determine
*GLOBAL* warming.

>     Lindy Weilgart and Hal Whitehead


P.J. Rovero                   Internet: rovero@oc.nps.navy.mil
Code OC/Rv                    Packet:   kk1d@k6ly
Naval Postgraduate School
Monterey, CA 93943