Abstract:

Model output of circulation, water mass and dynamical properties (currents, temperature, salinity, and sea level) for the Mississippi Bight and Mississippi Sound region of the northern Gulf of Mexico. The model application was developed as part of the GOMRI-funded CONCORDE consortium and has been configured with 400 m horizontal spatial resolution and 24 vertical layers. Observed freshwater input derived from available tide gauge stations are applied as riverine forcing, and Naval Research Laboratory-Naval Coastal Ocean Model (NRL-NCOM) output at 1km was used as outer boundary condition forcing. Surface atmospheric forcing is a low-passed (24-hour filtered) version of the 1km hourly product that was also developed as part of the CONCORDE consortium’s modeling component (the CONCORDE Meteorological Analysis- CMA). This filtering removes high-frequency meteorological forcing, such as diurnal sea breeze, allowing for scenario testing that reveals the impact of high-frequency winds on estuarine – shelf exchange. The model output in this dataset provides a daily resolution of physical parameters (currents, temperature, salinity, water levels) for the time frame around the Summer 2016 sampling campaign of the CONCORDE observational teams (2016-07-14 to 2016-10-11). The output provided also has seven regions of Eulerian dye tracer releases. The dye was released over the entire water column with a concentration of 1 for each of the regions: seaward of the Mississippi-Alabama Barrier Islands, seaward of the Chandeleur Barrier Islands, Mississippi Sound, Mississippi Bight, seaward of the Mississippi-Alabama Barrier islands that include the mouth of Mobile Bay, the Chandeleur Sound, and Mobile Bay. The dye was released as a passive tracer whose transport equation is the same as for salt-balance equation involving advective and diffusive transport and source-sink terms and does not influence the density field.

Suggested Citation:

Courtney Bouchard, Mike Dinniman, Brandy Armstrong, Jerry Wiggert. 2020. Physical Model of the Mississippi Sound and Bight from 2016-07-14 to 2016-10-11 with Low-Passed Meteorological Forcing and Eulerian Dye Tracer Releases for Residence Time Assessment. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/RXGWHKG3

Purpose:

The model output for this time frame from the CONCORDE synthetic model has been generated with the explicit purpose of providing environmental context to support the interpretation of the ship-based field measurements and biogeochemical signatures of submarine groundwater discharge obtained during the Summer field campaign of the CONCORDE consortium.

Data Parameters and Units:

Key parameters are Time (ocean_time [seconds elapsed since 2014-01-01 00:00:00]), latitude (lat_rho at the center of grid faces, lat_u at u velocity points, lat_v at v velocity_points, and lat_psi at grid nodes [decimal degrees N]), longitude (lon_rho at the center of grid faces, lon_u at u velocity points, lon_v at v velocity_points, and lon_psi at grid nodes [decimal degrees W]), u, u_eastward, and ubar (quasi-zonal, zonal, and vertically-integrated zonal velocity, [m/s]), v, v_northward, and vbar (quasi-meridional, meridional, and vertically-integrated meridional velocity, [m/s]), zeta (height of the free surface [m]), w (vertical velocity [m/s]), temp (potential temperature [degrees C]), salt (salinity), sustr (zonal surface momentum stress [N/m^2]), svstr (meridional momentum stress [N/m^2]), h (bathymetry [m]), s_rho (s-coordinate values at the rho-points [0:-1]), s_w (s-coordinate values at the w-points [0:-1]), and seven dye fields released: dye_01, dye_02, dye_03, dye_04, dye_05, dye_06, and dye_07 [kg/m^3] . Other included variables are the Coriolis parameter, wet/dry masks at all defined points, all parameters needed to convert s-coordinates to other vertical coordinate systems, the background diffusion coefficients, including switches for tracers, sources, sponge layers, climatology processing, and momentum field processing; time steps and intervals for histories, grid descriptions; diffusion and mixing coefficient fields; drag coefficients; surface and bottom roughness; and the angle between the grid coordinates and physical zonal/meridional coordinates.

Methods:

A COAWST-ROMS (Coupled Ocean Atmosphere Wave Sediment Transport-Regional Ocean Modeling System) model configured to the Mississippi Bight was used to simulate dynamics the Mississippi Sound and Mississippi Bight. Dye releases were modeled in seven regions of the Gulf of Mexico to help evaluate residence time, and low-pass (24-hour) filtered meteorological forcing allowed assessment of the effects of high-frequency winds on estuarine-shelf exchange. The original COAWST code is publicly available at https://www.usgs.gov/software/coupled-ocean-atmosphere-wave-sediment-transport-coawst-modeling-system.

Individual Files: