SATURN observation network: the workings and output of a long term biogeochemical
observatory in the Columbia River estuary
Michael P Wilkin1, Katie E Rathmell1, Jo A Goodman1, Charles Seaton2, Sarah Riseman2, Paul J. Turner2,
Albert A Little3, Joe Needoba2, António M. Baptista2
1&2Center
1Oregon
for Coastal Margin Observation and Prediction (CMOP)
Health & Science University (OHSU), MERTS Campus, Astoria, OR 2 OHSU, Portland, OR
3Clatsop Community College, Astoria, OR
Overview:
Observatories in coastal and estuary waters are a compromise with many competing
concepts. A commercially developed area with a long history of development and use
presents even more challenges. Opportunities for stations are rarely available where the
science would like, and those that are available may force data collection methods to
vary making uniformity difficult to find. Making stations reliable enough to keep the
logistic challenges of maintenance achievable may mean reducing the sampling below
the ideal.
CORIE started as a physical oceanography observatory around the Columbia Estuary, the
Observatory developed over the years to become the SATURN biogeochemical observation network with NSF
funding from CMOP and Murdock Foundation funding for major novel instrumentation.
Ocean conditions are observed to the north with ocean gliders and to the south with observation buoys.
There are two concepts to the ocean observations, how the ocean effects the estuary and how the estuary
effects the ocean. River conditions are monitored up stream by stations at Beaver Army Terminal, Bonneville
Dam, and Willamette River (these are not described here).
SATURN-02:
Situated in the North Channel this station is an automated winched
profiler, essentially a ship’s CTD, attached to guide wires on pier 12 of
the Astoria-Meglar bridge in 18m of water at chart datum. The profiler
oscillates up and down travelling at ~10cm/s, a single profile (up or
down) takes 3 to 4 minutes depending on the tide, followed by loitering
at the end point until the next 5 minute point is reached when the
profiler moves on again.
The speed of the profiler is a careful balancing act, move too fast and
the sensor can’t respond quickly enough to characterize the water
column, move too slowly and the environment changes faster than the
repeat profiling time. The loitering at the end of the profile allows
slower responding instruments to collect data effectively in the surface
water and bottom water parts of the water column.
The rapidly alternating salt-fresh water caused by the profiler’s up and
down movement serves to keep the package remarkable clean for
subsea deployed sensors. However the active mechanical nature of the
system means that a weekly service visit is necessary.
SATURN-04:
Situated at one of the entrances to Cathlamet Bay, this
station is at the end of a 500m long pier at Tongue Pt. The
station is a pumped port system similar to SATURN-03. The
quieter nature of the station allows a float to be used as the
upper intake with the pump moving up and down with the
tide. A davit and winch system allows the recovery and
service of the float and any associated instrumentation. A
second intake is located at the seabed.
The station serves as a “proving ground” for instruments and
systems before they move to the more aggressive and
dynamic environment at SATURN-03
A coastal ocean observing buoy,
stationed about 8km south of the tip
of the South Jetty in 40m of water.
Above the water is a meteorological
station, an AIS beacon and solar
panels for power. Immediately
underneath and mounted to the
frame of the buoy are sensors for CT,
CDOM, DO, nitrate and a MultiExciter that incorporates chla and
turbidity. Also mounted to the buoy
is a down looking acoustic velocity
profiler that can detect currents also
to the seabed in 50cm bins.
Further down the mooring string are
a series of CT sensors, until finally a
combined CT and DO sensors as
close to the seabed as the mooring
configuration will allow.
Instruments: CT, DO, chla, turbidity, pH,
nitrate, pCO2, CDOM;
Remote seabed frame: ADP
SATURN-03:
Situated in the South (navigation)
Channel, this station is a pumped
port configuration. Water is
pumped from 3 levels; near
surface, mid-water and seabed.
Submersible pumps are located at
each level with a temperature
sensor (as the temperature of the
water may be changed as it passes
through the water layers and
atmosphere above), hoses lead to
instruments housed in the building
above water. A series of computer
operated selector valves select a
level alternating each minute, the
remaining levels are simply
discharged back to the river
using bypass valves. The water flows through the
series of sensor flow cells before reaching an airbreak at the highest point, and then being
discharged back into the river. This, push from below
always uphill to the air break, ensures a positive
pressure is maintained throughout minimizing the
formation of air bubbles.
The pumps run continuously keeping the water at
the valves current with the water at the intake, only
first 30 seconds of the sampling period is required
Once logistics have been worked out, usually at
SATURN-04, the station can play host to occasional
or experimental instruments; this has included an
ESP, APNA, SeaFlow & CycleP.
Baker Bay is broad and shallow, finding a spot that allows the buoy ‘s instruments to observe the
passing water while not stirring up the sediments with a mooring chain, limits where the buoy
can be placed.
She has been outfitted by CMOP with an in hull ADCP, flow-through
instrument system and a telemetry link. The instrumentation is
switched on as part of the standard ship’s start up procedures and
collects data on every outing regardless who is on board.
An oceanographic winch, a heavy lift winch and a crane are also
fitted. CMOP conduct regular CTD cruises, with the seamanship
students operating the deck equipment, to monitor the performance
of SATURN and other stations.
Outside term time, MV Forerunner is used to collect a variety of
Oceanographic data and samples in the Estuary and Coastal
Waters
Instruments: CT, DO, CDOM, PE, Multi-exciter (includes chla & turbidity)
Phoebe and Dione:
Slocum Ocean Gliders propelled by buoyancy engines, first Phoebe (sadly lost to the
ocean) and now Dione survey the waters off the Washington Coast. The glider is
deployed for a month a time covering about 500km in a horizontal zigzag pattern
from 10 to 30nm offshore, and a vertical see-saw from the surface down to 200m in
depth before returning to the point of deployment for recovery
Instruments: C, T, depth, DO, chla, turbidity, CDOM
Quality Assurance:
Many anti-fouling strategies have been developed, but the usual
trade off is how much of the time can the sensor be exposed to the
environment compared to it being hidden behind a copper shutter or
in an quiet antifouling chamber. The more dynamic the environment,
the more often the sensor needs to be exposed; the Columbia
Estuary is a very dynamic environment.
The station is also equipped with a remote seabed
mounted acoustic velocity profiler.
The Estuary’s lateral bays seem quiet backwaters, however the tide constantly pumping water in
and out, solar heating of the shallows, and even their quiet nature, make these bays
fundamental to the ecosystem of the estuary. A buoy has been established in Baker Bay to
observe the changing waters in the bay, and a kayak outfitted with a similar set of instruments is
paddled around the bay by volunteers on summer weekends, extending the understanding of
the variation beyond the single point that the buoy observes.
The mooring is generally deployed in
the spring and recovered in the fall.
MV Forerunner is also
used to deploy and
recover oceanographic
buoys in the Estuary and
in Coastal waters, as well
as the remote seabed
mounted Acoustic
Profiler frames at
SATURN-01, 03 and 04.
Place an instrument in the water and it will give you a simple reading
of that parameter. Leave the instrument in the water and rapidly the
quality of that reading will start to degrade as the instrument
becomes covered in marine growth. Add additional stations and
inter-instrument accuracy starts to show that despite the initial cost
and accuracy of the sensors far more work is going to be required to
produce a worthwhile data set that has both wide spatially coverage
and long duration.
to flush the flow cells before valid data is collected
from the instruments.
SATURN-07:
MV Forerunner:
A 50’ former trawler owned and operated by Clatsop Community
College for seamanship training as part of their USCG Training Ship
program. The vessel cruises the estuary 2-3 times per week during
term time.
The major SATURN described attempt to cover as much of the diversity and variation as
possible, the smaller CORIE stations fill in some gaps and outfitted vessels give some
indication of what may be happening in between
In between are the Estuary stations observing the interaction between the River and Ocean. Here though
there are still very different environments to observe. There are two main river channels, the South shipping
SATURN-01:
Instruments: C, T, DO, Chla,
turbidity, CDOM, PE, nitrate,
quantum yield;
Remote seabed frame ADP, CT
Channel, runs right through, but the North channel truncates just east of the AstoriaMegar Bridge. To the side are lateral bays; Baker, Grays, Cathlamet and Youngs. These
lateral Bays are fundamental to the ecosystem of the Estuary.
Quality assurance starts with testing instruments in the workshop
before and after deployment and, where possible, recovering
instruments periodically for mid-deployment tests. Instruments are
recovered in groups of the same parameter to allow as much cross
comparison as possible. For the pumped stations (SATURN-03 & 04)
DI water is pumped through the flow cells each week to check the
drift of the instruments “zero offset”. Alternate weeks MV
Forerunner is utilized to perform CTD casts at as many stations as
practical, to provide cross comparison between stations, as well as
between instruments. Finally, water samples are collected for
laboratory analysis.
Essentially, monitoring the instruments is as important as
monitoring the Estuary if a good data set is to be produced.
Station Locations:
SATURN stations (01, 02, 03, 04 & 07)
CORIE stations:
• ogi01: offshore buoy
• jetta: Jetty A
• sandi: East Sand Island
• dsdma: Desdemona Sands light
• ncbn1: North Channel bottom node
• tansy: Tansy Point
• am169: Astoria-Meglar Bridge pier 169
• grays: Grays Point
• cbnc3: Cathlamet Bay North Channel (light 3)
• eliot: Elliot Point
• woody: Woody Island
Data Access:
Wherever possible data is returned to shore via a telemetry system consisting of 900MHz spread
spectrum radios and a 2.4GHz SWAP (Ship’s Wireless Access Protocol) system. Many stations also
have local storage; these are downloaded periodically or on recovery and the data combined with
the real-time data to fill outages resulting from telemetry issues.
All collected data is then made available via a web interface at www.stccmop.org. Images of data
for the last 2, 7 and 15 days are available through the station pages. In addition, the “Data
Explorer” interface allows data from multiple sources to be combined and displayed graphically
for periods ranging from the entire history of a station to a single day. This system covers all
accessible data collected since the observatory’s inception. The selected data sets can be freely
downloaded and the graphs saved to the user’s local computer.
CMOP’s data policy ensures that all
collected Oceanographic and
Environmental data is freely and
publicly available at the earliest
opportunity. Selected variables are also
accessible through NANOOS (the
regional association of ocean observing
systems) and through NDBC (the
national data buoy center).
Acknowledgements:
This material is based upon work supported in part by the National Science Foundation
under cooperative agreement OCE-0424602.
Murdock Foundation (major instrumentation)
Oregon Department of Transport (SATURN-01)
Point Adams Packing Company (SATURN-03)
Tongue Point Job Corps Center (SATURN-04)
Quinault Nation (Phoebe & Dione)
Submitted to: Columbia River Estuary Workshop 2014, Astoria, OR
Quality Control:
Development is always ongoing…..
Quality assurance protocols are in place prior to data collection to maximize
the likelihood that the data will be of the highest possible quality. However,
the raw data must also be evaluated in order to determine its actual quality.
The observation network is very responsive to changing requirements and new technologies.
However, in order to produce long term time series a certain inertia is required, if we start
something we like to keep it going for a prolonged period. In the Estuary it is frequently a case
of finding “stations of opportunity” rather than being able to develop a new station exactly
where we would like it.
This quality control process is sensor-specific and generally includes:
automated thresholds; visual inspection of the data to identify periods of
sensor malfunction or suspect data; a review of the data in the context of
other SATURN stations, both currently and within a historical context. In
addition, corrections may be made for issues such as sensor drift, bias, or
other artifacts.
Ultimately, the quality controlled data are assigned to one of five final quality
levels. This quality determination, along with any corrections made, is
detailed in supporting documentation available through metadata and web
pages.
Quality assurance and quality control protocols are continuously being
improved and adapted as more information and results become available.
Lateral Bays are increasing an area of interest, to accommodate this a new SATURN station is
planned for the center of the New Youngs Bay Bridge.
MV Forerunner represents an excellent platform for data collection as she regularly cruises
the Estuary year round in her primary task of seamanship training. Further instruments are to
be added to her flow-through system that is active whenever she is at sea.
For the shallow waters of the lateral bays a kayak has been outfitted with an instrumentation
suite. This suite is being reconfigured to suit CMOP’s inflatable RHIB so that this instrument
package can be used more regularly and in different bays than was possible with the
volunteer propelled kayak.
SATURN-04 & SATURN-03 are available for test deployment of new or novel instrumentation.