200
UWE SEND
In many applications, temporal resolution much higher than with
satellites, floats, and repeat ship sections is needed, as well as measurement
of a wider range of variables. This requires timeseries observations in fixed
locations, and for operational purposes a sustained mode of sampling is a
prerequisite. This leads to the useage of moored sensors or bottom-mounted
systems. The more generic modern expression is “ocean observatories”.
Sampling is possible, depending on sensors, from minutes to years, and from
the surface to the ocean bottom. There are “subsurface” and “surface”
moorings, depending on where the top buoy is located.
Moorings can carry heavy sensors and thus observe, in case an
autonomous instrument exists, nearly everything. Apart from physical
sensors for T, S, currents, there now are optical sensors (for radiation
measurements, chlorophyll fluorescence, oxygen), optical plankton counting
and video instruments, chemical sensors (analyzers with wet reagants, or
samplers), acoustic instruments for zooplankton backscatter or long-range
tomography transmissions, and more.
Mooring networks are a special case and provide high time resolution at
a set of fixed locations covering an ocean region. For dense networks like
the tropical TAO/TRITON array in the Pacific, spatial gradients are sought,
while more widely spaced systems sometimes only intend to contrast
differences between areas or to occupy different parts of an ocean region.
Application:
Since moorings can only be installed and maintained in a discrete
number of selected locations, the rationale normally is to use them in
locations with critical ocean processes or in places that are expected to be
representative of larger areas of an ocean basin. Examples are water mass
formation regions, where the location of the deep mixing process is well
known, and where a single mooring with sensors for water mass properties
(T, S, etc) and possibly vertical currents (ADCP sensor) is sufficient.
Similarly, flows and transports through important straits and passages, like
Denmark Strait, the Indonesian Passages, or the Strait of Gibraltar, could be
monitored by fixed observatories. Observing the uptake of CO 2 on the global
scale is also a crucial type of information, which can be provided by a
network of moorings with CO 2 sensors in the major regions of uptake or
release by the ocean. The concept of ecological ocean provinces (Longhurst
1995) helps to identify locations which may be representative of larger areas
in terms of chlorophyll and nutrient concentrations/distributions, mixedlayer depth, and other aspects. Maintaining observatories in each of these
global provinces might enable the detection of variability or regime shifts in
the different ecosystems.
In obtaining in-situ chlorophyll data, moorings will become an important
complement to satellite chlorophyll estimates, which are very difficult to
determine and have an accuracy of 30% in the best of cases. In addition,
UWE SEND
In many applications, temporal resolution much higher than with
satellites, floats, and repeat ship sections is needed, as well as measurement
of a wider range of variables. This requires timeseries observations in fixed
locations, and for operational purposes a sustained mode of sampling is a
prerequisite. This leads to the useage of moored sensors or bottom-mounted
systems. The more generic modern expression is “ocean observatories”.
Sampling is possible, depending on sensors, from minutes to years, and from
the surface to the ocean bottom. There are “subsurface” and “surface”
moorings, depending on where the top buoy is located.
Moorings can carry heavy sensors and thus observe, in case an
autonomous instrument exists, nearly everything. Apart from physical
sensors for T, S, currents, there now are optical sensors (for radiation
measurements, chlorophyll fluorescence, oxygen), optical plankton counting
and video instruments, chemical sensors (analyzers with wet reagants, or
samplers), acoustic instruments for zooplankton backscatter or long-range
tomography transmissions, and more.
Mooring networks are a special case and provide high time resolution at
a set of fixed locations covering an ocean region. For dense networks like
the tropical TAO/TRITON array in the Pacific, spatial gradients are sought,
while more widely spaced systems sometimes only intend to contrast
differences between areas or to occupy different parts of an ocean region.
Application:
Since moorings can only be installed and maintained in a discrete
number of selected locations, the rationale normally is to use them in
locations with critical ocean processes or in places that are expected to be
representative of larger areas of an ocean basin. Examples are water mass
formation regions, where the location of the deep mixing process is well
known, and where a single mooring with sensors for water mass properties
(T, S, etc) and possibly vertical currents (ADCP sensor) is sufficient.
Similarly, flows and transports through important straits and passages, like
Denmark Strait, the Indonesian Passages, or the Strait of Gibraltar, could be
monitored by fixed observatories. Observing the uptake of CO 2 on the global
scale is also a crucial type of information, which can be provided by a
network of moorings with CO 2 sensors in the major regions of uptake or
release by the ocean. The concept of ecological ocean provinces (Longhurst
1995) helps to identify locations which may be representative of larger areas
in terms of chlorophyll and nutrient concentrations/distributions, mixedlayer depth, and other aspects. Maintaining observatories in each of these
global provinces might enable the detection of variability or regime shifts in
the different ecosystems.
In obtaining in-situ chlorophyll data, moorings will become an important
complement to satellite chlorophyll estimates, which are very difficult to
determine and have an accuracy of 30% in the best of cases. In addition,