|An update on the numerical simulation of oceanographic processes in the waters between Vancouver Island and the mainland: the GF8 model|
Stronach, J.A.; Backhaus, J.O.; Murty, T.S. (1993). An update on the numerical simulation of oceanographic processes in the waters between Vancouver Island and the mainland: the GF8 model. Oceanogr. Mar. Biol. Ann. Rev. 31: 1-86
In: Oceanography and Marine Biology: An Annual Review. Aberdeen University Press/Allen & Unwin: London. ISSN 0078-3218, more
Mathematical models; Simulation; Marine
|Authors|| || Top |
- Stronach, J.A.
- Backhaus, J.O.
- Murty, T.S.
The numerical simulation of oceanographic processes in the waters consisting of the Strait of Georgia, Juan de Fuca Strait and Puget Sound was described in an earlier review. In the present review, an extension of those numerical simulations is described, concerning the development and verification of a new three-dimensional baroclinic model of the system. The model is called GF8, and represents the eighth in a series of models described in Crean et al. GF8 is based on a model developed for the North Sea by J. O. Backhaus. The dynamics, geometry and stratification of the Georgia-Fuca system are quite different from the North Sea, and numerous changes were required to yield a model that computes currents and elevations in energetic channels where currents exceed 5 ms-1, and in numerous regions of rapidly changing bathymetry. The model is implicit as far as external gravity waves are concerned, so that relatively large time steps can be used. GF8 uses a 2 km horizontal grid, and a variable number of layers in the vertical. The simulations presented in this review used a time step of 600 s and eight vertical levels. The forcing terms for GF8 consist of tidal elevations applied along the open boundaries, surface wind stress derived from coastal light house data, and Fraser River inflow. The initial density field is determined from bottle cast data collected monthly in 1968 and 1969. Density profiles at the open boundaries were also prescribed from the 1968 and 1969 data. Under these conditions GF8's reproduction of tidal elevations and currents is excellent, and of similar accuracy to GF7, its barotropic precursor, which was carefully calibrated. GF8 was also found to respond to seasonal changes in density structure and to surface wind forcing in an intuitively correct manner, consistent with the observational data base, and to reproduce baroclinic/topographic interactions such as internal tides in Johnstone Strait correctly, in agreement with current meter observations. GF8 has been used for multi-year simulations, and also in other British Columbia coastal water bodies. In all cases, GF8 has provided reliable velocity and density calculations. It has thus been demonstrated that GF8 is a reliable and accurate baroclinic model for coastal water bodies, and its use for engineering and scientific studies is both justified and highly recommended.