2
and telemetry, battery storage capacity, and electronic 3-D navigation have equally
improved. Availability of novel primary transducers together with these advances
has led to the development of robust, miniaturized, field deployable instruments.
The advent of electro-optical devices has revolutionized the capability for detecting
and measuring a wide range of chemical and biological variables and processes.
These advances have now reached the point of allowing sustained, widely distributed collection of environmental data by compact, autonomous instrument systems. Wide band dual communications allow remote operation of these networks
with ever-increasing capabilities. Hart and Martinez (2006) define such integrated
systems as environmental sensor networks where these capabilities are integrated
into systems providing multilayered, data-dense views of spatial and temporal variability of environmental conditions.
In the field of ocean science, expeditionary oceanographic research aboard
manned vessels provided an important testbed for the design and development of
such instrument systems. Today, instruments recording temperature and salinity and
other variables routinely operate at data sampling rates up to 24 Hz. Vertically operated profiling instruments known as CTDs (for conductivity (C), temperature (T)
and depth (D)), descending at rates up to 60 m.min
−1
thus achieve sampling densities up to 24 data points per meter or 120,000 data points for a full ocean depth cast
to 5000 m.
Instrumental Data: Then and Now
Fifty years ago a vertical hydrographic wire cast from a ship sampling to full
ocean depth would have sampled 24 data points using reversing mercury
thermometers for temperature measurement mounted on bottle samplers for
subsequent laboratory salinity and oxygen analyses making a total of 86 data
records including depth, derived from temperature anomalies of protected
versus non-protected thermometer pairs. Bottles were affixed sequentially to
a weighted wire rope and then tripped by means of bronze messengers
(weights sequentially traveling down the wire rope) to invert the thermometers and simultaneously trip the bottle to capture a water sample. Paired thermometers were read at sea (through a handheld magnifying glass) upon
retrieval of the array and salinity was determined with bench salinometers in
the laboratory. Dissolved oxygen and a few other variables were measured in
the laboratory using wet chemical techniques. The same cast today, performed
with sensor-based electronic instrumentation, obtains 5000 times more coupled depth, temperature, salinity and oxygen data points with real-time graphical representation, electronic readout, and digital data recording. Data density
may be increased severalfold by addition of various optical, bio-optical, and
opto-chemical sensor devices to the instrument package.
1 Introduction to Coastal Ocean Observing
and telemetry, battery storage capacity, and electronic 3-D navigation have equally
improved. Availability of novel primary transducers together with these advances
has led to the development of robust, miniaturized, field deployable instruments.
The advent of electro-optical devices has revolutionized the capability for detecting
and measuring a wide range of chemical and biological variables and processes.
These advances have now reached the point of allowing sustained, widely distributed collection of environmental data by compact, autonomous instrument systems. Wide band dual communications allow remote operation of these networks
with ever-increasing capabilities. Hart and Martinez (2006) define such integrated
systems as environmental sensor networks where these capabilities are integrated
into systems providing multilayered, data-dense views of spatial and temporal variability of environmental conditions.
In the field of ocean science, expeditionary oceanographic research aboard
manned vessels provided an important testbed for the design and development of
such instrument systems. Today, instruments recording temperature and salinity and
other variables routinely operate at data sampling rates up to 24 Hz. Vertically operated profiling instruments known as CTDs (for conductivity (C), temperature (T)
and depth (D)), descending at rates up to 60 m.min
−1
thus achieve sampling densities up to 24 data points per meter or 120,000 data points for a full ocean depth cast
to 5000 m.
Instrumental Data: Then and Now
Fifty years ago a vertical hydrographic wire cast from a ship sampling to full
ocean depth would have sampled 24 data points using reversing mercury
thermometers for temperature measurement mounted on bottle samplers for
subsequent laboratory salinity and oxygen analyses making a total of 86 data
records including depth, derived from temperature anomalies of protected
versus non-protected thermometer pairs. Bottles were affixed sequentially to
a weighted wire rope and then tripped by means of bronze messengers
(weights sequentially traveling down the wire rope) to invert the thermometers and simultaneously trip the bottle to capture a water sample. Paired thermometers were read at sea (through a handheld magnifying glass) upon
retrieval of the array and salinity was determined with bench salinometers in
the laboratory. Dissolved oxygen and a few other variables were measured in
the laboratory using wet chemical techniques. The same cast today, performed
with sensor-based electronic instrumentation, obtains 5000 times more coupled depth, temperature, salinity and oxygen data points with real-time graphical representation, electronic readout, and digital data recording. Data density
may be increased severalfold by addition of various optical, bio-optical, and
opto-chemical sensor devices to the instrument package.
1 Introduction to Coastal Ocean Observing