Abstract:
Impacts of submesoscale processes on transport are investigated numerically in an energetic mesoscale flow with an ocean model run at two horizontal resolutions, 1 and 5 km. The focus is the northwestern Gulf of Mexico, where the Loop Current eddies are surrounded by smaller vortices. By increasing the horizontal resolution, the number and strength of submesoscale eddies and vorticity filaments within the mixed layer increase dramatically and with them the vertical velocities. Inside the coherent eddies and at their peripheries, increased vertical velocities for increasing resolution are associated to near inertial motions and they are not limited to the mixed layer, but are found at all depths. Horizontal velocities, on the contrary, are similar. Lagrangian isobaric tracers are deployed close to the surface and at 100 m, and three-dimensional, neutrally buoyant particles are released close to the surface, at the base of the mixed layer and at 100 m. The modeled horizontal dispersion curves for each deployment depth are independent of the kind of particles and of horizontal resolution. Close to the ocean surface, however, convergence zones, generated by submesoscale ageostrophic motions and resolved at 1 km resolution, influence the details of the tracer distributions. Vertical dispersion increases by several folds for increasing resolution at all depths explored, with the largest differences found close to the surface.
Data Parameters and Units:
gom1km-bry-20050401.nc -- theta_s, S-coordinate surface control parameter (non-dimensional) theta_b, S-coordinate bottom control parameter (non-dimensional) Tcline, S-coordinate surface/bottom layer width (meter) hc, S-coordinate parameter, critical depth (meter) sc_r, S-coordinate at RHO-points (non-dimensional) [-1 0] Cs_r, S-coordinate stretching curves at RHO-points (non-dimensional) [-1,0] bry_time, time for boundary data (day) temp_south, southern boundary potential temperature (Celsius) salt_south, southern boundary salinity (PSU) u_south, southern boundary u-momentum component (meter/second) v_south, southern boundary v-momentum component (meter/second) ubar_south, southern boundary vertically integrated u-momentum component (meter/second) vbar_south, southern boundary vertically integrated v-momentum component (meter/second) zeta_south, southern boundary sea surface height (meter) temp_east, eastern boundary potential temperature (Celsius) salt_east, eastern boundary salinity (PSU) u_east, eastern boundary u-momentum component (meter/second) v_east, eastern boundary v-momentum component (meter/second) ubar_east, eastern boundary vertically integrated u-momentum component (meter/second) vbar_east, eastern boundary vertically integrated v-momentum component (meter/second) zeta_east, eastern boundary sea surface height (meter) dye_east_01, dye concentration eastern boundary condition (kilogram/meter^3) dye_south_01, dye concentration southern boundary condition (kilgram/meter^3) dye_east_02, dye concentration eastern boundary condition (kilogram/meter^3) dye_south_02, dye concentration southern boundary condition (kilogram/meter^3) gom1km-frc-nudg.nc -- sst_time, sea surface temperature time (day) SST, sea surface temperature (Celsius) dQdSST, surface net heat flux sensitivity to SST (Watts/{meter^2*Celsius}) sss_time, sea surface salinity time (day) SSS, sea surface salinity (PSU) gom1km-frc-shf-200504-6hrly.nc -- shf_time, surface heat flux time (day) shflux, surface net heat flux (Watts/meter^2) gom1km-frc-srf-200506-6hrly.nc -- srf_time, solar shortwave radiation time (day) swrad, solar shortwave radiation (Watt/meter^2) (downward/upward flux, heating/cooling) gom1km-frc-swf-200504-6hrly.nc -- swf_time, surface freshwater flux time (day) swflux, surface freshwater flux (E-P) (centimeter/day) (net evaporation/precipitation) gom1km-frc-wind-200506-6hrly.nc -- sms_time, surface momentum stress time, (day) sustr, surface u-momentum stress (Newton/meter^2) svstr, surface v-momentum stress (Newton/meter^2) gom1km-grid-new.nc -- xl, domain length in the XI-direction (meter) el, domain length in the ETA-direction (meter) depthmin, Shallow bathymetry clipping depth (meter) depthmax, Deep bathymetry clipping depth (meter) spherical, Grid type logical switch refine_coef, Grid refinment coefficient grd_pos, Subgrid location in the parent grid: psi corner points (imin imax jmin jmax) angle, angle between xi axis and east (degree) h, Final bathymetry at RHO-points (meter) hraw, Working bathymetry at RHO-points (meter) alpha, Weights between coarse and fine grids at RHO-points f, Coriolis parameter at RHO-points (1/second) pm, curvilinear coordinate metric in XI (1/meter) pn, curvilinear coordinate metric in ETA (1/meter) dndx, xi derivative of inverse metric factor pn (meter) dmde, eta derivative of inverse metric factor pm (meter) x_rho, x location of RHO-points (meter) x_u, x location of U-points (meter) x_v, x location of V-points (meter) x_psi, x location of PSI-points (meter) y_rho, y location of RHO-points (meter) y_u, y location of U-points (meter) y_v, y location of V-points (meter) y_psi, y location of PSI-points (meter) lon_rho, longitude of RHO-points (degrees East) lon_u, longitude of U-points (degrees East) lon_v, longitude of V-points (degrees East) lon_psi, longitude of PSI-points (degrees East) lat_rho, latitude of RHO-points (degrees North) lat_u, latitude of U-points (degrees North) lat_v, latitude of V-points (degrees North) lat_psi, latitude of PSI-points (degree North) mask_rho, mask on RHO-points (land, water) mask_u, mask on U-points (land, water) mask_v, mask on V-points (land, water) mask_psi, mask on PSI-points (land, water)
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