Methods and systems disclosed herein relate generally to ocean modeling, and more specifically to solving for advection diffusion reaction of dissolved or particulate tracers in aquatic environments.
The currents and action of fluid motion are constant environmental perturbations to the wide range of chemical and biological interactions that occur in the ocean. Physical ocean computer models take atmospheric forcing as input and attempt to calculate the future trend of the ocean's physical state, e.g., current speed and direction, turbulence, wave heights, ocean salinity and temperature. These physical model forecasts can help in the scientific study and potentially the forecasting of dissolved and particulate materials in the oceans, coastal domains and estuaries. Biogeochemical modeling takes advantage of the ability of physical ocean models to properly describe and forecast fluid motions. The underlying basis to biogeochemical models is that a simulated field (an array of point material concentrations over a multi-dimensional grid) of some set of biological or chemical constituents is subject to physical transport in ocean currents, that the physical model will adequately describe the advection and diffusion of the materials, and additional terms can be added to describe biological interactions or chemical reactions. Hence biogeochemical models are essentially a description of time-dependent advection diffusion-reaction (ADR) for specified ocean constituents. Dispersion is the action or process of distributing materials over a wide area—specific to fluid dynamics this refers to the combined action of advection and diffusion of dissolved and suspended particulate materials that results in a change in the three-dimensional distribution of these materials over time. It is fundamental to the ADR calculation that the ocean physics is represented, and so the physical ocean circulation models are an integral component of any potential ADR system. A direct way to construct a coupled ADR computer model is to integrate the advection and diffusion of a biological/chemical tracer field directly into the physical ocean computer model software. An additional set of tracers can be added to advection and diffusion computations for temperature and salinity. Additional software code can be added to describe the reactions and interactions of these additional field properties. Direct coupling can present practical concerns to investigations focused on the “reaction” portion of the ADR simulation such as, for example, but not limited to, the fact that biological and ecosystem interactions tend to be both complex and poorly constrained by either first principles or direct observation. As a practical matter, work towards development of prognostic ADR equations requires multiple iterations of various “R” formulations, often with excessively large parameter lists. Setting the complexity of ecosystems aside, even the decay rates for certain dissolved chemical materials may be very poorly constrained. Research in these areas using ADR simulations can require that multiple or “ensemble” sets of computer simulations will be performed. Re-calculating the ocean physics for each simulation can be wasteful and superfluous. Also, source code and forcing fields for the physical ocean model may not be available, and only the results from the physical model (in the form of velocity fields) can be accessible to the investigator. It also may be the case that the extensive computational resources required to execute the physical ocean model are only intermittently available. In these situations, the direct ADR coupling method may not be a pragmatic solution.
An offline coupler of the prior art performs a two-dimensional advection computation (surface only) based on ocean circulation model results, but does not solve for continuity or obey mass conservation. Thus, the offline coupler introduced spurious artifacts into the ADR solution and diminished the apparent quality and utility of the forecast products.
What is needed is a system by which the results from a single execution of an ocean circulation model may be used to drive a separate ADR computer simulation and compute a tracer forecast. What is further needed is a system that does not require that the velocity fields are from an ocean circulation model, they could be analysis fields derived from some other source, such as high frequency RADAR observations or satellite-based surface ocean velocity inversion/detection methods.
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