. Changes in the vertical arrival angle of sound
rays as they pass through a front can cause towed array
It is clear that any one of these effects can have a
significant impact on ASW operations. Together they
determine the mode and range of sound propagation and
thus control the effectiveness of both short- and
long-range acoustic systems. The combined effect of
these characteristics is so complex that it is not always
possible to develop simple rules for using ocean fronts
for ASW tactics. For example, the warm core of the
Gulf Stream south of Newfoundland will bend sound
rays downward into the deep sound channel, thereby
enhancing the receiving capability of a deep receiver.
The same situation with a slightly shallower bottom
south of Maine may create a bottom-limited situation,
and the receiving capability at the same hydrophore will
be impeded. In view of this, the acoustic effects of a
front must be determined for each particular situation
by using multiprofile (range-dependent environment)
acoustic models. The input for these models can come
from detailed oceanographic measurements, or from
historical data in combination with surface frontal
positions obtained from satellites.
DETERMINING FRONTAL POSITION
USING SATELLITE DATA
Most fronts exhibit surface-temperature signatures
that can be detected by satellite infrared (IR) sensors and
are used in determining frontal positions. Figure 9-17
is an example of a satellite IR image obtained by the
TIROS-N showing the location of the Gulf Stream and
formation of a warm ring. Because surface-temperature
gradients are not always reliable indicators of the
subsurface front, satellite images must be interpreted by
a skilled analyst, preferably in combination with data
from other sources such as BTs. Automatic
interpretation of satellite data is also being developed
using techniques generally known as automatic
imagery-pattern recognition or artificial intelligence.
Now lets discuss oceanographic effects on mine
warfare (MIW). Environmental Effects on Weapons
Systems and Naval Warfare (U), (S)RP1, provides
further detail on this subject.
LEARNING OBJECTIVES Recognize the
parameters affecting MIW operations. Identify
the various mine hunting sonars. Be familiar
with the procedures for obtaining MIW support
MIW is the strategic and tactical use of sea
mines and their countermeasures. MIW may
be offensive (mining to interfere with enemy
ship movement) or defensive (mining to defend
friendly waters [mine-countermeasures]) in nature.
Mine warfare is almost always conducted in
nearshore areas that present special environmental
conditions not usually encountered in open ocean areas,
. Sound speed that is highly dependent upon
salinity. Although salinity may be treated as constant
for open ocean areas, fresh water runoff creates strong
salinity gradients in nearshore areas.
l Ambient noise that is higher than normal.
l Biologic activity levels and diversity that are
. Nearshore areas that typically have a high level
of nonmilitary activity.
. Land runoff that generates much more turbidity
than for open ocean areas.
MINE WARFARE ENVIRONMENTAL
MIW planning (mining and mine countermeasures)
requires a considerable environmental input. The
following parameters should be considered for
discussion in any MIW environmental support
Physical properties of water column