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The coastal ocean has a number of unique physical and meteorological processes that promote high biological productivity, active sedimentary processes, dynamic chemical transformations and intense air-sea interactions. In addition to being an area of great scientific interest, the coastal ocean is a region of the global hydrosphere that has special societal importance. Key societal issues include coastal navigation, coastal hazards such as flooding and erosion, the utilization of renewable resources (e.g. fisheries) and nonrenewable resources (e.g. minerals, sand, and petroleum), while minimizing environmental damage. As more of the world’s population shifts towards coastal areas, human impacts on the coastal ocean in terms of pollution, waste disposal and recreation continue to increase. Sensible management decisions require greater fundamental comprehension of how the coastal ocean system functions.
Coastal Ocean Processes (CoOP) is a program that seeks to plan and implement multi-investigator, interdisciplinary research in the coastal ocean. CoOP encompasses the disciplines of Biological, Chemical, Geological and Physical Oceanography, plus Marine Meteorology. CoOP defines the coastal ocean as extending from the surf zone to the edge of the continental rise, an area generally ranging from 100 to 1000 km offshore. CoOP’s definition of the coastal ocean also includes large inland bodies of water (the Great Lakes) that exhibit processes similar to those in the ocean.
The goal of CoOP is to obtain a new level of quantitative understanding of the processes that dominate the transports, transformations and fates of biologically, chemically and geologically important matter on continental margins. This active transport links geophysical processes at work near the coast to those operating over the continental shelf and beyond. CoOP’s underlying scientific planning assumption is that a series of well designed, interdisciplinary processes studies will provide significant new information to advance our understanding of coastal oceans that will have applicability to the continental margins around the world. Coupled process studies and modeling are the core of CoOP research programs. Primary support of CoOP comes from the National Science Foundation. In addition, both NOAA and the Office of Naval Research have funded CoOP planning activities as well field process studies.
CoOP RESEARCH PLANS
The CoOP research plan is to conduct process and modeling studies on shelves which differ in the dominant physical processes which influence cross margin transport. CoOP studies will thus attempt to isolate the key processes that have some global generality and to study these in detail on margins where effects can be isolated with a maximum degree of confidence. Modeling studies will be integrated with the process studies and used as a means to synthesize and generalize study results. Five shelf types that CoOP will study are:
Wind-driven Transport - The defining characteristic of this shelf type is that current fluctuations are predominantly driven by winds (either locally or remote) on time scales longer than a day. A subset of these shelves are those where seasonal upwelling occurs, such as off the California and Oregon coasts as well as shelves of Portugal, Southwest Africa and western South America. The broader category of wind-driven transport would include all of the U.S. continental shelves.
Tidally-driven Transport - In areas such as Georges Bank and the Bering Sea, strong tides can determine mixing processes and mean flows. High tidal amplitudes are generally the result of a wave resonance in a "cavity", so that tidally dominated regions tend to be in or near areas with complex coastlines.
Buoyancy-driven Transport - Fresh water discharge from rivers creates an alongshore flow. In areas where the freshwater discharge is relatively low (Middle Atlantic Bight) buoyancy- driven transport is limited to the inner shelf. However, in areas of heavy precipitation such as the south coast of Alaska and off Norway, buoyancy-driven flows can dominate the entire shelf.
Western Boundary Current (WBC) shelves - Cross margin transport on these shelves can be influenced by strong ocean offshore currents such as the Gulf Stream and Kuroshio as well as eddies that originate from strong boundary currents. This category would thus include all of the Atlantic seaboard as well as the Gulf of Mexico (due to the Loop Current).
Ice-covered Shelves - In the Great Lakes and Northern Alaska there are seasonally ice-covered shelves. Ice formation and brine rejection can result in the formation of deep or intermediate water mass formation which can contribute to cross-shelf transport. Once ice is formed, it can strongly mitigate exchanges of heat and momentum between the ocean and atmosphere.
CoOP STUDIES
Inner Shelf Dynamics - The first CoOP study was initiated off Duck, NC in 1992 in response to a call for proposals to study transport on inner shelves. This region has not been widely studied because the strong wave activity on the inner shelf makes it is difficult to maintain moorings and to operate ships. The interdisciplinary CoOP project focused on the suspension and cross-shelf transport of sediments and the planktonic larvae of inner shelf benthic invertebrates. The investigators used both a cross-shelf array and ship surveys to study the physics, sediments and plankton of the inner shelf. Conditions of both upwelling and downwelling favorable winds during the study period resulted in different water property characteristics as well as larval concentrations. The patterns of larval abundance are a consequence of habitat affinities of the different taxa as well as wind-driven cross-shelf transport.
Coastal Air-Sea Chemical Fluxes - In order to develop a quantitative, mechanistic understanding of how gases are transported between the coastal atmosphere and ocean, CoOP initiated a program to improve our ability to estimate chemical fluxes in coastal regions. In 1995 a cooperative program was developed between CoOP and the Office of Naval Research (ONR) sponsored Marine Boundary Layer Research Initiative and the Minerals Management Service (MMS). CoOP investigators focused on air-sea gas exchange; MMS studied surface flux and Langmuir circulation dynamics; and, ONR’s research effort focused on exchange of momentum, heat aerosols, and the dynamics of the atmosphere and oceanic boundary layers. CoOP investigators developed both new both underway mapping systems and moored in situ sensors to measure gases.
Great Lakes Processes Studies - In 1997 CoOP in collaboration with the NOAA Coastal Ocean Program began interdisciplinary process studies on cross-margin transport in the Great Lakes. The study of Episodic Events: Great Lakes Experiment (EEGLE) will focus on the role of the annually recurrent southern Lake Michigan plume in transporting material across the margins of Lake Michigan. Mooring arrays, ship surveys, drifter studies and radar sites will be used to track the plume, surface currents and the particle field. Another CoOP Great Lakes project is The Keweenaw Interdisciplinary Transport Experiment in Superior (KITES). The Keweenaw Current forms a semi-permeable barrier along the coast that inhibits shore and river derived material from crossing the central basin of Lake Superior. Water movement in this current is the primary means for transport of material from the western to eastern lake basin and is therefore likely to be important in dictating productivity throughout the whole lake.
CoOP PLANS
Wind-driven Transport Study - In 1998 CoOP will solicit proposals for an interdisciplinary process study of wind-driven transport. The focus area of the study will be the U.S. west coast off Oregon and California where both upwelling and downwelling can occur and the upwelling front varies in it’s distance from shore. The wind-driven transport shelves of the NE Pacific have high biological production, strong air-sea interactions and are important in particle and solute transport The central focus of this planned study is to determine the processes that control the cross-margin (inshore to offshore) transport of biological, chemical and geological materials in a strongly wind-driven system. CoOP is currently funding a modeling study to investigate the effects of three-dimensional wind-forced circulation processes on ecosystem dynamics under both upwelling and downwelling conditions.
Buoyancy-Driven Transport - In the fall of 1998 CoOP will conduct an open workshop to develop a Science Plan for a buoyancy-driven transport study. It is anticipated that planning efforts will lead to a CoOP process study of buoyancy-driven transport.
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