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FVCOM is a prognostic, unstructured grid, finite-volume, free-surface, three-dimensional (3-D) primitive equations ocean model developed by Chen et al. (2003a). The original version of FVCOM consists of momentum, continuity, temperature, salinity and density equations and is closed physically and mathematically using the Mellor and Yamada level 2.5 turbulent closure scheme for vertical mixing and the Smagorinsky turbulent closure scheme for horizontal mixing. The irregular bottom topography is represented using a σ-coordinate transformation, and the horizontal grids are comprised of unstructured triangular cells. FVCOM solves the governing equations in integral form by computing fluxes between non-overlapping horizontal triangular control volumes. This finite-volume approach combines the best of finite-element methods (FEM) for geometric flexibility and finite-difference methods (FDM) for simple discrete structures and computational efficiency. This numerical approach also provides a much better representation of mass, momentum, salt, and heat conservation in coastal and estuarine regions with complex geometry. The conservative nature of FVCOM in addition to its flexible grid topology and code simplicity make FVCOM ideally suited for interdisciplinary application in the coastal ocean.

The initial development of FVCOM was started by a team effort led by C. Chen in 1999 at the University of Georgia with support from the Georgia Sea Grant College Program. This first version was designed to simulate the 3-D current and transports within the estuary/tidal creek/inter-tidal salt marsh complex and was written in Fortran 77 in 2001. In 2001, C. Chen moved to the School of Marine Science and Technology at the University of Massachusetts-Dartmouth (SMAST/UMASS-D) and established the Marine Ecosystem Dynamics Modeling (MEDM) Laboratory where work on FVCOM has continued with funding from several sources under Chen’s leadership. The scientific team led by C. Chen and R. C. Beardsley built the original structure of FVCOM and conducted a series of model validation experiments. G. Cowles joined the MEDM group in 2003 and directly contributed to converting FVCOM to Fortran 90/95, modularized the coding structure and added the capability for parallel computation. The present version of FVCOM includes a nudging data assimilation module added by H. Liu, an improved 3D wet/dry point treatment module modified and tested by J. Qi, several choices for freshwater discharge and groundwater input and turbulence modules by C. Chen, H. Liu and G. Cowles, a tracer-tracking module by Q. Xu, and a 3-D Lagrangian particle tracking code (originally written by C. Chen and L. Zheng, modified by H. Liu to fit the FVCOM, and corrected by G. Cowles). A spherical coordinate version of FVCOM is also available for a basin or global scale application. The conversion from the local Cartesian coordinates to the spherical coordinates was first made based on the original Fortran 77 code of FVCOM by J. Zhu, a visiting scholar from the East China Normal University in Shanghai, P.R. China in 2002, and was subsequently migrated to Fortran 90/95 by Q. Xu and J. Qi and to a parallel version by G. Cowles in 2004.

In the early stage of the FVCOM development, D. Chapman at the Wood Hole Oceanographic Institution (WHOI) gave many valuable suggestions and comments on the code structure and model validation. F. Dupont (while a postdoctoral investigator at the Bedford Institute of Oceanography (BIO) added an ice formation model into FVCOM. J. Pringle at the University of New Hampshire (UNH) was one of the first users and contributed to including the wind-induced water transport input at the upwind open boundary condition in the model application to the Gulf of Maine/Georges Bank region. Many people in the MEDM group have contributed to FVCOM validations and applications, including the Mount Hope Bay (Massachusetts) modeling by L. Zhao, the Okatee Estuary (South Carolina) by H. Huang, the Satilla River (Georgia) by J. Qi, the Ogeechee River (Georgia) by H. Lin and J. Qi, the South China Sea by Q. Xu and H. Lin, and dye experiments on Georges Bank by Q. Xu. Several types of companion finite-volume biological models have been developed and coupled into FVCOM by the MEDM ecosystem model team led by C. Chen. They include: a) a nutrient-phytoplankton-zooplankton (NPZ) model developed by Franks and Chen (1996; 2001), b) an 8-component phosphorus-limited, lower trophic level food web model (nutrients, two sizes of phytoplankton, two sizes of zooplankton, detritus and bacteria: NPZDB) developed by Chen et al. (2002), c) a state-of the art water quality model with inclusion of the benthic flux developed by Zheng and Chen (Zheng et al. 2004), and d) a 9-component coastal ocean NPZD model developed by Ji and Chen (Ji, 2003). A 3-D sediment model developed by Zheng and Chen (Zheng et al., 2003b) was also added into FVCOM. As the FVCOM development team leader, Dr. Changsheng Chen reserves all rights of this product. The University of Massachusetts-Dartmouth and the Georgia Sea Grant Program share the copyright of the software of this model. All copyrights are reserved. Unauthorized reproduction and distribution of this program are expressly prohibited. This program is only permitted for use in non-commercial academic research and education. The commercial use is subject to a fee charge. Modification is not encouraged for users who do not have a deep understanding of the code structures and finite-volume numerical methods used in FVCOM. Contributions made to correcting and modifying the program will be credited, but not affect copyrights. For public use, all users should name this model as "FVCOM". In any publications with the use of FVCOM, acknowledgement must be included.

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