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Jack Barth (Moderator), Richard Dewey (Moderator), and Jent Campbell (Rapporteur)
Science Challenge and Why Orion
Processes occurring over the continental shelves generally occur on short time and space scales compared with processes in the open ocean, and event-scale phenomena often have a critical impact. This calls for more concentrated measurements in time and space. In particular, there is lack of understanding and quantification of spatial gradients of dynamic physical, chemical and biological properties near the interfaces:
Why do we need to know this? Gradients (both horizontal and vertical) are critical for estimating advective fluxes which can dominate local change. There are often enhanced responses (e.g. primary production, prey concentration) at these interfaces that may be orders-of-magnitude larger than the background and thus have a pronounced effect on the mean. These responses may be unaccounted for in large-scale estimates and models. ORION will provide fixed and moveable assets in the coastal ocean and overlying atmosphere to make the necessary fine-resolution, continuous, multi-parameter observations to quantify spatial (horizontal and vertical) gradients at appropriate scales.
EXAMPLES OF ORION EXPERIMENTS
What are the fluxes of energy and materials across continental margins and how do these fluxes vary in space and time? The science strategy for this question requires quantification of the mixing and elemental exchanges at the system boundaries. Given a rigorous budget, efforts focus on understanding the transformation of material on the continental shelves. Specific focuses include:
Shelf-deep ocean exchange and margin mixing: How and where does boundary mixing influence maintenance of the oceanic thermocline structure, vertical mixing of nutrients, and horizontal transport of these properties into the interior?
What we know: we can observe the vertical density structure of the ocean and know how to explain density in terms of heat input from above warming the surface layer, which mixes with deep cold water. The mystery is why the density structure looks like it does. Calculations of the mixing “coefficient” would indicate that there is not enough mixing (due to eddy diffusion processes) to explain the deep thermocline. Where does the mixing come from?
Bottom boundary layer/benthic-pelagic coupling: Despite agreement that benthic processes are important to continental shelf ecosystems, there has not been a means to effectively benthic-pelagic coupling coupling of ecologically relevant temporal and spatial scales. Observatories open a new window to the sea floor. When located on the shelf or slope, they will allow us to answer questions such as:
Exchanges in high-gradient regions of inner shelf ~10 km (ocean and air): Given the high turbulence in this environment, there is a need for fine-scale resolution to measure gradients in this region. The range of scales that need to be resolved are 100 m to 10 km for shelf-wide circulation models, and smaller 10-100 m for solitons and internal waves. Questions that need to addressed include:
Atmospheric inputs to the surface ocean cannot be measured from shore because the chemistry is altered over the ocean. This calls for surface sensors (not just bottom arrays) to measure physical and chemical properties of the marine boundary layer (MBL). ORION would provide the backbone for those sensors.
In river-dominated environments, episodic events can be very important (e.g., DOM from one major rain event can represent major portion of annual flux). The quantification of the significance of plumes requires a rapid response capability to alert scientists of event that is beginning to occur. Feature-tracking capabilities allowing scientists to stay within a feature such as a plume, front, eddy, bloom, etc. (e.g., smart floats) is also a key need. Use of mobile devices (e.g., gliders, AUVs) can sample shallow waters or get into places that can’t be sampled by other means.
For understanding the ecosystem dynamics and broad observational array ios required. This array would be used to calculate seasonal events. This includes quantifying the timing of the spring bloom which is central to the biogeochemistry and foodweb dynamics central to the transformation rates on the shelf. Additionally the spatial time series from the ORION infrastructure would provide the capacity to document regime shifts that are known to occur in which the biological community structure (note not necessarily at all trophic levels) changes dramatically over a short (~1-2 year) period. What are the causes of regime shifts?
To arrive at answers to the driving scientific questions will require different experimental designs for different regions/boundary locations. Observation System Simulation Experiments (OSSEs) can be used to determine the placement of fixed and moveable assets for a particular coastal region. Spacing will vary depending on the gradients, and this calls for a nested approach.
In general, horizontal spatial scales will range from 100 m (sharp horizontal fronts, internal soliton convergence zones, and nearshore) to 100 km (east-coast shelf width, several wavelengths alongshore of baroclinic instability waves/eddies). Vertical scales will range from 1 to 1000 m. Time scales range over a wide spectrum: from minutes (internal soliton periods); to hours (resolve tides); daily (diel cycle); episodic (days to weeks, e.g. storms, wind events, blooms); seasonal (net annual production); interannual (El Nino/La Nina); interdecadal (modulation by Pacific Decadal Oscillation, Naorth Atlantic Oscillation, etc.)
To sample at appropriate spatial and temporal scales calls for a nested approach with higher spatial resolution in the inner shelf (~10km) and at the shelfbreak, and higher vertical resolution in surface and bottom boundary layers within the ocean, and in the atmospheric MBL above the surface. The goal is to resolve exchange across interfaces on shoreward side of shelf and at the shelfbreak (both enhanced vertical mixing near-bottom on upper slope and subsequent advection along-isopycnal and horizontal exchange across shelfbreak separating shelf from adjacent deep ocean).
Horizontal array design: Fine-spatial resolution (1-5 km) near coastal feature of interest is required (river/estuary mouth, cape, etc.). Cross-shelf spacing of fixed assets (moorings telemetering to shore) on central line (the line intersecting the feature) should be 1-5 km. Similar spacing in the alongshore direction extending out to about +/- 20 km. Fine cross-shelf spacing around shelfbreak (a few to 5 km) is recommended. Coarser alongshore spacing to far field (~10 km over entire ~100 km region). These arrays should be complemented with mobile assets (e.g., gliders) in far field (i.e., to set offshore and alongshore boundary conditions). Also use mobile assets to better define short spatial scales (100 m to a few kilometers) within study region and to track features and their edges. Use HF land-based radar to get hourly maps of high-spatial resolution surface currents (2-3 km in inner nest; 8-10 km to far field).
Vertical array design: Vertical array design should be optimized to investigate benthic-pelagic coupling, mid-shelf benthic-estuary/nearshore coupling and air-sea interaction. The resolution should be: 1 m over entire water column for T, S, chlorophyll fluorescence, and bio-optical properties; 2 m over entire water column < 100 m deep for velocity; 20-50 cm for velocity in surface and bottom boundary layers. A Vertical Profiling System (VPS) capable of 25-50 cm/s speed can cover 200 m in 400-800 s (6.6-13.3 minutes) and thus repeat the cycle every ½-1 hour. The VPS should be minimally capable of operating in 2 knot (1 m/s) currents and year-round wave conditions (up to 30 feet for PNW).
Atmospheric sensors should resolve the MBL (order 200-500 m thick), especially near the coastal barrier, i.e. within about 10-20 km of the coast. Atmospheric parameters to be measured include temperature, humidity, wind speed and direction, chemical concentrations (e.g., CO2, DMS, etc.), and aerosols. (Note: the AERONET is a worldwide network of aerosol monitoring sensors used to monitor air quality and provide input for interpreting satellite observations. Recently, a few such sensors have been located on platforms offshore, and this trend should continue).
Lagrangian Techniques: We recommend that the observatory network be complemented with lagrangian floats (constant pressure, isopycnal, constant elevation above bottom, with behavior to mimic larvae), smart tags/sensors, and dyes as tracers during focused process studies.
Bottom Boundary Layer Needs: The bottom boundary layer can be sampled with profilers (AUVs, gliders) (“bouncers”), rovers capable of conducting experiments in sediments (“creepers”, “diggers”), and platforms capable of constant elevation above bottom (“cruisers”, “helicopters”). Inexpensive bottom pressure sensors should be developed to be placed everywhere to measure bottom pressure gradients.
Table xx. Episodic processes on continental shelves that require an ocean observatory.
emote Sensing Techniques: A geostationary coastal satellite with visible and infrared sensors would provide superior time resolution as compared with current polar-orbiting satellites. Hyperspectral color measurements might make it possible to resolve concentrations of materials with complex spectral signatures as well as solar-induced fluorescence. In-situ sensors in the coastal ocean will provide calibration and validation measurements to complement the satellite remote sensor systems. Aircraft-based remote sensing platforms (viewed as “facilities”) would provide superior spatial resolution.
The proposed array represents a nested observation network that would provide spatial time series. The sampling resolution (time and space) will be sufficiently high so that episodic events can be resolved within the annual and seasonal cycles. These episodic events represent quantitatively significant features within the annual cycles; however traditional sampling techniques do a poor job in resolving them. Fundamental to ORION is developing the network to study these events. The actual design of the array will of course be dependent on the specific process being studied (Table XX). Designing the array will require up front planning and it is recommended that an “event template” be developed for designing and operating the arrays during the episodic events (See Box XX).
Where to place Pioneer Arrays? These features of interest should be chosen through a competitive peer review process. Selection should also cover a wide range of conditions that would facilitate focused process experiments and facilitate comparative studies. These research sites should include interesting features such as river/estuary mouths, a range of coastal topographies (capes, islands, areas of local intensification), bottom topography (banks, canyons), biogeographic boundaries, biological hot spots, and exclusion zones (fishing).
Instrument and Sensor Technology
BAS: Bio-Acoustic Spectroscopy. From vertical moorings, equipped with low level transmitters (200-10 kHz, 170 dB), and arrays of receivers, one can detect and map out the bio-mass distribution using “forward scatter resonance”. Mooring separation is 2-5 km. (Figure contributed by ? Orest Diachok email@example.com)
hysical Oceanography has a suite of mature ocean sensors that are easily adapted for observatory deployments (CTD, ADCP). Chemical Oceanography has laboratory and specialized/delicate sensors that will need to be modified and tested for long-term deployment on observatories. Research into more advanced anti-fouling techniques for optical and chemical sensors is a high priority. Biological Oceanography is significantly behind both PO and CO in sensor development. A major effort is required to advance biological sensor technology up to the standards of physical ocean sensors. The use of acoustics and video may be initial avenues of pursuit.
Autonomous and lagrangian platforms (ALPS) will be key components to a coastal observatory, providing essential spatial mapping and event detection. Remote programming and command and control of fleets of “flyers”, both in the water and above will allow researchers to “respond” to events detected by moored sensors. Sensors on ALPS will include all disciplines (physical, chemical and bio-acoustics). Observatories with Eulerian data alone will limit and frustrate our ability to take advantage of the real-time, continuous nature of observatory information.
Exciting new sensors that are under development include: bio-acoustic absorption spectroscopy (see figure); phytoplankton identification sensors on AUVs (flow cytometers, FlowCam, HPLC, fluorescence, excitation/emission fluo.); bar-coded fish tags; other smart sensor tags that record environmental variables as well as position; feature tracking devices.
Education and Outreach
The coastal ocean is engaging to the public -- even for audiences in non-coastal states. Processes such as HABs, storms, winds and waves are of widespread interest. The observing data acquired by ORION needs to be converted into “information products” (value added), and there needs to be “portals” created to take these products to the public. The COSEE centers could serve this purpose, particularly for educators and students. Displays at museums and aquariums would reach the non-formal education audiences. Television and radio “ocean weather” reports would also be a means of broadcasting results. All this will require dedicated personnel involving scientists, educators, and other user groups, and adequate funding.
The goal for education should be to change how students view science from “science is something that is done by others for you to learn about” to “science is something that is happening now that you can participate in.” Education materials should emphasize what scientists don’t know as much as what they know, since the mysteries of science are often more compelling than learning a collection of facts or rules. However, care must be taken not to give the idea that well-accepted facts are subject to varying interpretations.
It would be worthwhile for ORION to develop an inexpensive “tool box” to enable students to design their own observing system – e.g., to engage in shore-based sampling programs – and provide them with computer models and data. Working with scientists, data and models can be used in the development of curricula. Data mining over the Internet is an easily implemented inquiry-based activity, but teachers need training to learn about the availability of data archives and how to access them. Training should be provided to preservice (undergrad) teachers as well as to practicing teachers. There should be plenty of follow-up with teachers after formal training sessions (e.g., summer workshops). Follow-up would include occasional meetings to get teachers together during the school year following a summer workshop, and email and telephone assistance to answer questions that arise throughout the year.
Successful activities should be presented at National Science Teacher Associate conferences and other such venues. Activities should be peer-reviewed by scientists and educators for accuracy and effectiveness.
One of the major concerns is that academic scientists who participate in outreach and education activities are often not recognized or rewarded (e.g., when promotion and tenure decisions are made). There should be a cultural shift to value these activities. Can NSF play a role in this?
For expanding out the footprint of the OIRION community leveraging off a range of other scientific programs may be useful. For example, the EPSCOR program might be used to help bring Puerto Rico into ORION.
Experiments for Now and Future
The Kick-off Experiment:
“Kick-off” experiments would be subject to the usual NSF criteria (scientific merit, broad impact). Other criteria should be: (1) select areas with high knowledge of processes and their scales (time and space) to maximize the chance to capture an event/feature of interest; (2) build on existing infrastructure; (3) don’t select an extreme environment first.
The goal is to produce an immediate success story through a significantly improved understanding of an event-scale phenomenon (e.g., HABs, blooms, etc.). By measuring over 1-2 years, the experiment will observe 25-50 realizations of events lasting 2 weeks. Group recommends:
Experiments 5-Years from now will employ:
Experiments 20-Years from now will employ:
Potential River-Shelf Sites:
Mississippi River (features which could be studied include: hypoxia, sediment, canyon, Loop Eddies, nutrients, climate impacts, infrastructure, industrial impacts, watersheds)
Columbia River (salmon, micronutrients like iron, low nutrient ecosystems, ENSO, PDO, thin layers, infrastructure, microbial community)
Hudson River (human impacts, hypoxia, canyon-plume interactions, heavy metals and ecosystems, NAO)
Chesapeake Bay (watershed, high human interest/impact, biogeochemical processes inside estuary< NAO)
Southeast Alaska (“natural” environment, sediment, nitrogen cycle, salmon, line source, non-estuary, PDO)
Potential Margin mixing/shelfbreak exchange:
Middle Atlantic Bight (climate signal via NAO, shelfbreak jet conduit from upstream, instabilities, eddies, Gulf Stream ring interactions, historical data, infrastructure, internal tide generation especially as influenced by presence of shelfbreak front/jet)
South Atlantic Bight (western boundary current, shallow and wide shelf, high benthic production, groundwater inputs, infrastructure)
West Florida Shelf (Loop Current, HABs)
West coast (Vancouver Island, PNW, California, Baja) (separated jets, strong wind-driven upwelling/downwelling, flow-topography interaction, ENSO, PDO, internal tide generation, infrastructure)
Southeast Alaska (buoyancy-driven front, nutrient exchange, sediment exchange, presence of Alaska Stream)
Miscellaneous Concerns, Issues and Recommendations:
Members and Affiliations:
Jack Barth, Oregon State University
Richard Dewey, University of Victoria
Janet Campbell, University of New Hampshire
Amy Cline, University of New Hampshire
Curtiss Daviss, Naval Research Laboratory
Orest Diachok, NRL
Glen Gawarkiewicz, WHOI
Rick Jahnke, Skidaway
Barbara Kirkpatrick, Mote Marine Lab.
Gary Kirkpatrick, Mote Marine Lab.
Dave Maier, OHSU
Carrie McDougall, NOAA Office of Education
Maia McGuire, Florida Sea Grant
Jay Pinckney, TAMU
Dana Savidge, Skidaway
Larry Smarr, UC San Diego
Amos Winter, Marine Geol. & Geoph., NSF
Plate Dynamics Working Group Report
Mark Zumberge (Moderator), Del Bohnenstiehl (Rapporteur)
Science Challenge and Why Orion.
What drives plate tectonics? Is it from pressure developed at spreading centers, traction along the base of the plate from moving asthenosphere, or traction from subduction slabs?
Marine geophysicists have long recognized that detailed examination of episodic events (e.g., earthquakes at spreading centers, transform boundaries, and subduction zones; volcanic eruptions, diking), and of pre- and post- episode conditions, would lead to a far better understanding of what drives plate tectonics. By “capturing” plate boundary ‘events’ it should be possible to determine cause and effect relationships between major processes. Important short-term goals are to:
A longer term goal is to understand the plate boundary energy budget and determine the temporal and spatial scales of various deformation processes. With ORION infrastructure, we could gain understanding of:
ORION will provide the power and communications necessary for deploying suites of continuously recording instruments and sensors to capture events and bring us to an understanding of the role such events play in longer-term boundary deformation.
To capture events at a range of plate boundaries will require a number of suites of instruments to be deployed in specific areas. Three examples (at a spreading center, at a subduction zone, and within a plate) are described.
Instrument and Sensor Technology
The marine geophysics community has suites of mature instruments and sensors to be used to continuously monitor activity if power, bandwidth, and communications are provided by ORION.
Core sensor suite
In the model for a cabled observatory, or a buoy supported observatory, a series of nodes or “junction boxes” is envisaged. The following suite of instruments should be included at each node:
Sensors for specific sites or experiments
In many cases, focused studies will be undertaken at specific well defined sites:
1. Area crossing a spreading center axis that has shown recent (in the last decade) magmatic activity -
Sensors to be deployed densely across a spreading center include:
Closely spaced geophones (1Hz) crossing the ridge axis
Strong motion seismometers
Fluid, chemical, and biological sensors
Strainmeters (e.g., acoustic or fiber optic)
Optical sensors (acoustic Doppler imaging, cameras)
Sensors to be deployed by ROV or air-dropped in response to an event include:
Rapidly deployable hydrophones
Water column sampling
Less time-critical responses to an event would include:
Repeat reflection seismology
2. At a subduction zone to examine the potential rupture area for subduction zone megathrust earthquakes, how it varies along the subduction zone, and what the seismic hazard is from a large megathrust event, e.g., along Cascadia margin -
The figure on the left shows a 2-D elastic model of deformation for a locked subduction zone; the figure on the right shows the geographic location of the locked zone. When the fault zone is locked the overriding plate is flexed upward. The seaward limit of the locked zone, which is a primary control on tsunami size, is not constrained by land geodetic data. Long-term geophysical observations in the ocean, specifically seafloor geodetic data, are required to extend profiles based on data collected on-land offshore and accurately model this deformation. The landward limit of the locked zone, which is critical for determining the dimensions of the rupture zone and predictions of earthquake shaking, is also located offshore and ocean observations (both seismic and geodetic) will be required to better constrain the landward limit of the locked zone. Other sensors on the seafloor and in boreholes are needed to measure fluid flow and pore fluid pressures - fluid pressures, for example, may affect fault rupture potential.
3. Long-term studies of intraplate deformation -
A plate-scale geophysical observatory (e.g., Juan de Fuca Ridge) can be used to investigate plate boundary interactions. It is now clear from recent studies on land that stress transfer is a fundamental mechanism controlling fault interaction and aftershock clustering. There are also hints from recent studies that oceanic plates can transmit stresses rapidly over 100s of km. For example, the 400-km long band of intense mid-plate seismicity observed in the Gorda plate in 1991-1992, and shown here in the figure on the left, ceased following a magnitude 7.2 earthquake in the Cape Mendocino region, in this area. As shown by the figure on the right seismicity levels on the Gorda plate decreased dramatically in the years after this event. It has been proposed that the Cape Mendocino event relieved stress in the Gorda plate by triggering movement in the adjacent subduction zone along here.
Efforts to “capture” events and their consequences will require existing and new instrumentation for basic nodes in a cabled observatory and specialized equipment for specific experimental work targeted at individual sites or phenomena. There are also requirements for new instrumentation needed for rapid responses to events.
Education and Communications
Projects to monitor and “capture” events should have a required outreach component. The ORION Office could provide a central easily identified contact for PIs, and well-designed templates (geared to teachers, students, and the public) for PIs to use with their project and with the type of data they will be collecting (e.g., an easy to use “plug and play” template).
The ORION Office could also maintain a network of teachers who are interested in going to sea and who can/or are trained to produce educationally useful materials for web sites or other materials and who are tasked with riding herd on PIs during and after the project. These people need to be partners with the PIs throughout the planning stage after funding (or even before if the PI requests).
For education efforts, the details of providing such things as how lesson plans meet national education standards (this could be for an expedition, instrument development, monitoring effort or event response) need to be provided for the PI.
Media involvement should be encouraged in the form of documentaries.
A number of hands-on involvement opportunities are envisioned (e.g., contests for instrument and or equipment/experiment design).
Direct involvement of undergraduates through internships should be a priority.
EXPERIMENTS FOR NOW AND FUTURE
Five year goals
The Nootka Fault zone extending southwest from Victoria Island, and accessible from the cable planned for NEPTUNE Canada, could conceivably produce a significant earthquake area within five years, ORION participants should seek collaborations to begin studies there.
ORION infrastructure should also be emplaced to detect and monitor after effects of events:
Plans should be made to:
Twenty year goals
After the ORION program has been ongoing for two decades, we would hope to:
While the plates are defined by similar characteristics and boundary types, there are important differences among them. These include fast versus slow spreading, different types of subduction zones, and different overall sizes. Clearly there is an advantage to studying the plates in a variety of these settings and over a variety of scales.
Site selection, as witnessed by the recent RIDGE 2000 process, can be an arduous and contentious task. Our breakout group was able to agree on a fairly short list of sites taking into account current and past research activity and ongoing programs that would mesh well with seafloor observatories. Sites that are high on the priority list of the Plate Dynamics group are:
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