202 AlIan R. Robinson and Jurgen SelIschopp
In military operations, there is room for improvement by REA (Sellschopp,
1999). In many cases, overt REA operations may be carried out without antagonist
interference. To give an example: In an oceanographically active region, the saf est
route may be found by REA to bring a convoy across. Survey results will be kept
secret for a few weeks, positions of survey deployments not. In a not totally unrealistic scenario, navy units are sent to an area that is close to a focus of mischief.
Good knowledge of the littoral environment is eminent and can be obtained via
REA, the results of which need not be c1assified.
In denied areas one would not deploy survey ships. Remote sensing from satellites and aircraft is primarily useful for the investigation of surface features. Except
for visible light, electromagnetic waves are not appropriate for illumination below
the sea surface. Surf ace signatures are, however, often caused by subsurface features, such as the transformation of surface waves by currents or bathymetry.
Air deployed autonomous systems are an alternative for ship measurements.
Buoys may be moored or drift through a denied area and from time to time transmit
data to an aircraft or satellite. For several weeks of continuous operation, a bottom
deployed trawl-safe system can collect water column data; it can use a small popup buoy with an antenna to send the data at programmed intervals. Autonomous
underwater vehicles are becoming increasingly important for underwater research
and surveying. Their appropriateness for denied areas is coupled with high
expenses for bridging the range from the deployment position. In summary, REA is
aggravated but still feasible in a hostile military environment.
11.1.3 Civilian REA
At tirst glance it might seem that rapidity is not an issue in civilian environmentaI assessment except for standard products such as storm surge prediction. But
there are scenarios, that would compel REA operations. An appropriate reaction to
natural disasters or accidents might be impeded by lack of knowledge about environmental parameters such as mixing rates or time variable current fields. With an
REA capability in place, it could be possible to close the knowledge gap in a timely
manner. REA methodology should also be applied when management plans at-sea
events such as byproduct dumping. Dnce an ocean area is sufficient1y precisely
mode1ed, variations of forcing fields will cost effective1y yield the potential impact
of the management event on the environment.
11.2 Nowcasting and Forecasting the Physics
The water column physical state variables associated with the circulation and its
variabilities play a central role in the prediction ofmany REA parameters ofinterest. The fundamental physical state variables (velocity components, pressure, temperature, salinity, density) evolve in time according to the coupled conservation
laws for momentum, mass, heat and salt, and the equation of state. We will treat
those scales and phenomena whose dynamics are adequate1y approximated explic-
In military operations, there is room for improvement by REA (Sellschopp,
1999). In many cases, overt REA operations may be carried out without antagonist
interference. To give an example: In an oceanographically active region, the saf est
route may be found by REA to bring a convoy across. Survey results will be kept
secret for a few weeks, positions of survey deployments not. In a not totally unrealistic scenario, navy units are sent to an area that is close to a focus of mischief.
Good knowledge of the littoral environment is eminent and can be obtained via
REA, the results of which need not be c1assified.
In denied areas one would not deploy survey ships. Remote sensing from satellites and aircraft is primarily useful for the investigation of surface features. Except
for visible light, electromagnetic waves are not appropriate for illumination below
the sea surface. Surf ace signatures are, however, often caused by subsurface features, such as the transformation of surface waves by currents or bathymetry.
Air deployed autonomous systems are an alternative for ship measurements.
Buoys may be moored or drift through a denied area and from time to time transmit
data to an aircraft or satellite. For several weeks of continuous operation, a bottom
deployed trawl-safe system can collect water column data; it can use a small popup buoy with an antenna to send the data at programmed intervals. Autonomous
underwater vehicles are becoming increasingly important for underwater research
and surveying. Their appropriateness for denied areas is coupled with high
expenses for bridging the range from the deployment position. In summary, REA is
aggravated but still feasible in a hostile military environment.
11.1.3 Civilian REA
At tirst glance it might seem that rapidity is not an issue in civilian environmentaI assessment except for standard products such as storm surge prediction. But
there are scenarios, that would compel REA operations. An appropriate reaction to
natural disasters or accidents might be impeded by lack of knowledge about environmental parameters such as mixing rates or time variable current fields. With an
REA capability in place, it could be possible to close the knowledge gap in a timely
manner. REA methodology should also be applied when management plans at-sea
events such as byproduct dumping. Dnce an ocean area is sufficient1y precisely
mode1ed, variations of forcing fields will cost effective1y yield the potential impact
of the management event on the environment.
11.2 Nowcasting and Forecasting the Physics
The water column physical state variables associated with the circulation and its
variabilities play a central role in the prediction ofmany REA parameters ofinterest. The fundamental physical state variables (velocity components, pressure, temperature, salinity, density) evolve in time according to the coupled conservation
laws for momentum, mass, heat and salt, and the equation of state. We will treat
those scales and phenomena whose dynamics are adequate1y approximated explic-