Bahamas

Caption: Let to right and top to bottom, six-hour interval snapshots showing temperature and current vectors in the Bahamas model revealing the influence of the tide on the Bahamas shallow banks (for instance south and west of Andros...)

Caption: semi Lagrangian trajectories from active particles released from reef areas in the Outer Bahamas and the Florid Strait. Color shows the age in days of the particles.

Description:

The model domain is centered on the Bahamas Islands, and extends from the Abaccos to the south of Turk and Caicos. It resolves the transport through the Windward Passage, the Florida Strait, the Old Bahama Channel and the Northwest Providence Channel. On-line nested zooms are set-up on demand based on the focus of the study. Model output will be made available on-line through a thredds server.

Resolution:

The horizontal resolution is 5 km and the minimum depth is 8m because of steepness constraint in sigma coordinate models. Themodel has 25 vertical layers. With such resolution, and due to the steep slope next the the banks some topographic features are not present in the model topography. This could lead to some unrealistic current patterns in some areas although being accurate elsewhere. The topography used for this simulation is the 1' General Bathymetric Chart of the Oceans (GEBCO, http://www.gebco.net/), hand modified near some of the shallow banks. It is the most accurate topography publicly available for the Bahamas

A new simulation with twice the resolution has been started in order to resolve all the important shallow topographic features that force the flow. The new minimum depth is 3m, more consistent with the depth of the Bahamas banks.

Nested:

Yes. This is an off-line nesting within the outer model, which doesn't use the AGRIF package since both models are not run at the same time.

Initial conditions:

January 1^st 2005 Atlantic HYCOM simulation.

Outer conditions:

The model uses a weekly relaxation to the Atlantic HYCOM simulation at its boundaries for the period 2005-2006.

Tides:

Tides were set at the boundaries by the TPXO6 global tide model.

Forcing:

Monthly varying surface fluxes (wind, rain, solar, radiative heat fluxes, evaporation) were obtained from the Comprehensive Ocean Atmosphere Dataset COADS climatology. Wind stress were obtained from QuikSCAT scatterometer.

For the new simulation 4-times daily atmospheric forcing are obtained from theNavy Operational Global Atmospheric Prediction System (NOGAPS) and Coupled Ocean Atmosphere Mesoscale Prediction System (COAMPS). Bulk fluxes capability of the ROMS model will be used. We aimed to resolve diurnal cooling and heating on the shallow banks in order to simulate overflow from the banks to the deep basins.

Applications:

The main application of this simulation is for the Bahamas Biocomplexity Project in order to study:

(1) connectivity patterns and dispersal kernels for coral reefs organisms (Mumby et al., submitted)

(2) Marine protected areas connectivity

(3) Marine sponges population dynamics and connectivity under harvest pressure

(4) Lobster larvae connectivity in the Turk and Caicos

Contacts:

Laurent Cherubin - lcherubin@rsmas.miami.edu

Claire Paris - cparis@rsmas.miami.edu

Peter Mumby - P.J.Mumby@exeter.ac.uk