Re: Radar, sonar and more

G'day,

>No. 2 Will an abnormally loud aquatic environment
>prevent the effective use of sonar?

Massive chemical or temperature shifts inside the water column - they
act
as a barrier and you've got #@% of getting a correct return. I've seen
guys
track a single zooplankter (about 0.5mm) through the water column not a
problem and then bang hit the thermocline and they wouldn't be able to
find
a whale even if it was sitting there waving at them! The problem would
be
exascerbated if your pycnocline (density break-point) was either large
or
there were multiplte ones betwen water masses with different chemical
make-ups similarly with haloclines (salinity based break-points).
Biological swarms (even things as small as femtoplankton which is
0.00000001 m in diameter) can through it out if congregrating in huge
numbers in a bloom or what-not. This kinda problem is why there are
still
so many marine charts on Earth that have 'island' or 'shoals' marked on
them where there are none - the mapper was hitting either a
thermo/pycno/halocline or a group of fish. 

Hope that helps

Beth

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Elizabeth Fulton
c/o CSIRO Division of Marine Research
GPO Box 1538
HOBART 
TASMANIA 7001
AUSTRALIA
Phone (03) 6232 5018 International +61 3 6232 5018
Fax 03 6232 5053 International +61 3 6232 5053

email: beth.fulton@marine.csiro.au