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Regional Ocean Modeling System. Free surface, hydrostatic ocean model Finite-difference 3D Reynolds-averaged Navier-Stokes equations Horizontal orthogonal curvilinear Arakawa C grid Vertical stretched terrain-following Sigma coordinates
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Regional Ocean Modeling System • Free surface, hydrostatic ocean model • Finite-difference 3D Reynolds-averaged Navier-Stokes equations • Horizontal orthogonal curvilinear Arakawa C grid • Vertical stretched terrain-following Sigma coordinates • Wide range of advection schemes: (e.g. 3rd-order upstream-biased, 4th-order) • Wide range of open boundary conditions: (e.g. Radiation, clamped, nudged) • CF-compliant NetCDF I/O • Wide range of vertical mixing schemes (k-epsilon, k-omega, MY2.5, KPP, GLS) • Ice models • Biological modules • Model adjoint for data assimilation • Fortran 90; Runs on Unix, Mac, and Windows • Parallel code in MPI and OpenMP
ROMS wiki - lots of good information https://www.myroms.org/wiki http://www.people.arsc.edu/~kate/ROMS/manual_2012.pdf
Wide Range of realistic Applications 10 km wide island 1,000 km long coastline DongMcWilliamsShchepetkin(2004) 10,000 km wide basin ArangoHaidvogelWilkin(2003) Gruber et al (2004)
W r Dm Wind L H Test Cases • Open channel flow 3) Mixed layer deepening 2) Closed basin, wind-driven circulation 4) Tidal flow around a headland 5) Estuarine circulation http://woodshole.er.usgs.gov/project-pages/sediment-transport/
ROMS Grid - masking - curvature - stretching terrain following coordinates Horizontal Arakawa "C" grid Vertical eta xi
Terrain following transformations (Vtransform + Vstrectching) Vtransform 1 2 https://www.myroms.org/wiki/index.php/Vertical_S-coordinate
Vertical stretching Vstretch 1 IF (Vstretching(ng).eq.1) THEN ! Original vertical strectching function, Song and Haidvogel (1994), defined as: ! ! C(s) = (1 - b) * [SINH(s * a) / SINH(a)] + ! b * [-0.5 + 0.5 * TANH(a * (s + 0.5)) / TANH(0.5 * a)] ! ELSE IF (Vstretching(ng).eq.2) THEN ! A. Shchepetkin vertical stretching function. This function was improved further to allow ! bottom refiment (see Vstretching=4). This vertical stretching function is defined as ! ! C(s) = [1.0 - COSH(theta_s * s)] / [COSH(theta_s) - 1.0] ! ELSE IF (Vstretching(ng).eq.3) THEN ! R. Geyer stretching function for high bottom boundary layer resolution. This stretching ! function is intended for very shallow coastal applications, like gravity sediment flows. ! ! At the surface, C(s=0)=0 ! C(s) = - LOG(COSH(Hscale * ABS(s) ** alpha)) / ! LOG(COSH(Hscale)) ! ! At the bottom, C(s=-1)=-1 ! C(s) = LOG(COSH(Hscale * (s + 1) ** beta)) / ! LOG(COSH(Hscale)) - 1 ! ELSE IF (Vstretching(ng).eq.4) THEN ! A. Shchepetkin improved double vertical stretching functions with bottom refiment. ! This vertical stretching function is defined as ! ! C(s) = [1.0 - COSH(theta_s * s)] / [COSH(theta_s) - 1.0] ! 2 3 4
Vstretch 1 2 3 4
Equations in Mass Flux form u, v, = Eulerian Velocity ul, vl, = Lagrangian Velocity ust,vst, = Stokes Velocity f = Coriolis parameter φ = Dynamic pressure Hz = Grid cell thickness = Non wave body force = Momentum mixing terms = Non-conservative wave force Continuity xi-direction Momentum Balance
eta-Direction Momentum Balance ACC = Local Acceleration HA = Horizontal Advection VA = Vertical Advection COR = Coriolis Force StCOR = Stokes-Coriolis Force PG = Pressure Gradient HVF = Horizontal Vortex Force BF = Body Force BA+RA+BuSt+SuSt = Breaking Acceleration+ Roller Acceleration+ Bottom Streaming+ Surface Streaming HM = Horizontal Mixing VM = Vertical Mixing Fcurv = Curvilinear terms Description of Terms Kumar, N., Voulgaris, G., Warner, J.C., and M., Olabarrieta (2012). Implementation of a vortex force formalism in a coupled modeling system for inner-shelf and surf-zone applications. Ocean Modelling, 47, 65-95.
Solution techniques- mode splitting Shchepetkin, A. F., and J. C. McWilliams, 2008: Computational kernel algorithms for fine-scale, multi-process, long-time oceanic simulations. In: Handbook of Numerical Analysis: Computational Methods for the Ocean and the Atmosphere, eds. R. Temam & J. Tribbia, Elsevier Science, ISBN-10: 0444518932, ISBN-13: 978-0444518934.
Numerical algorithms Advection schemes - 2nd order centered - 4th order centered - 4th order Akima - 3rd order upwind -MPDATA many choices, see manual for details. ……
How do we select different schemes • c pre -procssor definitions (list them in *.h file) • during compilatoin, F f90s • compiles f90's into objects • compiles objects to libs • ar the libs to make 1 exe • for coupling, it makes wrf, roms, and/or swan as libs, then pull them together for couplingand only produces one exe.
COAWST cpp options • #define ROMS_MODEL if you want to use the ROMS model • #define SWAN_MODEL if you want to use the SWAN model • #define WRF_MODEL if you want to use the WRF model • #define MCT_LIB if you have more than one model selected and you want to couple them • #define UV_KIRBY compute "depth-avg" current based on Hwaveto be sent from the ocn to the wav model for coupling • #define UV_CONST send vel = 0 from the ocn to wave model • #define ZETA_CONST send zeta = 0 from the ocn to wave model • #define ATM2OCN_FLUXES provide consistent fluxes between atm and ocn. • #define MCT_INTERP_WV2AT allows grid interpolation between the wave and atmosphere models • #define MCT_INTERP_OC2AT allows grid interpolation between the ocean and atmosphere models • #define MCT_INTERP_OC2WV allows grid interpolation between the ocean and wave models • #define REFINED_GRID allows grid refinement in roms or in swan • #define COARE_TAYLOR_YELLAND wave enhanced roughness • #define COARE_OOST wave enhanced roughness • #define DRENNAN wave enhanced roughness + …………..
ROMS Application example:US East Coast 1) grid 2) bathy 3) masking 4) 3D: BC's (u,v,temp,salt), init, and climatology 5) 2D: BC's (ubar, vbar, zeta) = tides 6) Surface forcing (heat and momentum fluxes) 7) roms input file 8) coawst.bash 9) run it
1) Grid generation tools • Seagrid - matlab http://woodshole.er.usgs.gov/operations/ modeling/seagrid/ (needs unsupported netcdf interface) • gridgen - command line http://code.google.com/p/gridgen-c/ • EASYGRID
1) Grid generation tools • COAWST/Tools/mfiles/mtools/wrf2roms _mw.m function wrf2roms_mw(theWRFFile, theROMSFile) Generates a ROMS grid from a WRF grid. • COAWST/Tools/mfiles/mtools/create_roms_xygrid.m intended for simple rectilinear grids • or any other method that you know
1) Grid generation tools May also need a coastline, can obtain this here: http://www.ngdc.noaa.gov/mgg/coast/ save as coastline.dat
1) Grid generation tools US_eastgrd19.nc - generated from matlab tools (seagrid I think, but here is a quick way ) lonx=[-93.50 -101.75; -53.25 -60.75]; laty=[11.75 30.75; 30.50 48.50]; rho.lon=interpn(lonx,7); rho.lat=interpn(laty,7); rho.lon=rho.lon(:,10:end); rho.lat=rho.lat(:,10:end); rho.depth=rho.lon*0; rho.mask=rho.lon*0+1; spherical='T'; projection='mercator'; save grid.mat mat2roms_mw('grid.mat','Useast_grd.nc') netcdf_load('USeast_grd.nc') % now plot the grid coastline=load('coastline.dat'); figure plot(coastline(:,1),coastline(:,2)) hold on plot(lon_psi(1:5:end, 1:5:end),lat_psi(1:5:end,1:5:end),'k') plot(lon_psi(1:5:end, 1:5:end)',lat_psi(1:5:end,1:5:end)','k') r2 r1 c2 c1 Matlab (row, col)
2) bathymetry many sources Coastal Relief Model ETOPO2 LIDAR
2) bathymetry - You need to interpolate bathy to the variable 'h' located at your grid rho points (lon_rh, lat_rho). - Bathymetry can be smoothed using http://drobilica.irb.hr/~mathieu/Bathymetry/index.html
Grid Parameters Beckman & Haidvogel number (1993) Haney number (1991) should be < 0.2 but can be fine up to ~ 0.4 determined only by smoothing should be < 9 but can be fine up to ~ 16 in some cases determined by smoothing AND vertical coordinate functions If these numbers are too large, you will get large pressure gradient errors and Courant number violations and the model will typically blow up right away
3) masking 1) first create a matlab coastline file lon=coastline(:,1); lat=coastline(:,2); save coastline.matlonlat 2) use COAWST/Tools/mfiles/mtools/editmask m file (from Rutgers, but I changed it to use native matlabnetcdf) editmask('USeast_grd.nc','coastline.mat')
4) 3D BC's (u,v,temp,salt), init, and clima. COAWST/Tools/mfiles/roms_clm/roms_master_climatology_coawst_mw.m This works for 1 time step. Needs nctoolbox to acess data via thredds server. Future release will have this capaiblity in matlab and not require this toolbox. http://code.google.com/p/nctoolbox/
4) 3D BC's (u,v,temp,salt), init, and clima. can use Tools/mfiles/roms_clm/roms_combine_clm_bdy.m to combine the BC and climatology files. (needs a few modifications for more generality)
5) 2D: BC's (ubar, vbar, zeta) = tides This uses the older netcdf interface.
5) 2D: BC's (ubar, vbar, zeta) = tides 1) Get the tidal data at svncheckout https://coawstmodel.sourcerepo.com/coawstmodel/data . 2) edit Tools/mfiles/tides/create_roms_tides
5) 2D: BC's (ubar, vbar, zeta) = tides can also use the analytical functions, such as ana_fsobc ana_m2obc An example of this will be shown tomorrow.
6) Surface forcings (heat + momentum) COAWST/Tools/mfiles/mtools/ narr2romsnc creates netcdf forcing files for ROMS. Many others tools available. Can also use ana_functions.
6) Surface forcings (heat + momentum) COAWST/Tools/mfiles/mtools/ create_roms_forcings creates netcdf forcing files for ROMS. Many others tools available.
