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 Applications10 km wide island

10,000 km wide basin

DongMcWilliamsShchepetkin(2004)

ArangoHaidvogelWilkin(2003)

1,000 km long coastline

Gruber et al (2004)

Test Cases

1) Open channel flow

5) Estuarine circulation

2) Closed basin,

wind-driven circulation

Wind

H

L

W

4) Tidal flow around

a headland

3) Mixed layer deepening

rDm

http://woodshole.er.usgs.gov/project-pages/sediment-transport/

ROMS Grid

Vertical

HorizontalArakawa "C" grid

- masking- curvature- stretching

terrain following coordinates

xi

eta

Terrain following transformations

https://www.myroms.org/wiki/index.php/Vertical_S-coordinate

Vtransform

1

2

(Vtransform + Vstrectching)

Vstretch

1

2

3

4

Equations in Mass Flux form

Continuity

0ll lsz z zH H u H v

t mn n m s mn

ACC HA

St Stz z z z zH H u H v H u H v

u u u u ut mn n m n m

�������������� �

1

1

St st c

st Sts s zz z z s

z

Hfv fv v uu u H H H v

s mn s mn mn mn n n m

� ��������������

VA COR StCOR PG

us mn

����������������������������������������������������� ���� ������������������������������������������

' '

HVF

BF BA

ˆ w

uz z z

z

H H H D v uu w

mn mn mn s H s

�

�������������� �

F FF

+RA+BtSt+SuSt HM VM FCurv

����������������������������������������������������� ���� ������������������������������������������

xi-direction Momentum Balance

u, v, = Eulerian Velocityul, vl, = Lagrangian Velocity

ust, vst, = Stokes Velocityf = Coriolis parameterφ = Dynamic pressureHz = Grid cell thickness

= Non wave body force = Momentum mixing terms = Non-conservative wave force

, , ,l l St St u u u

eta-Direction Momentum Balance

ACC HA

St Stz z z z zH H u H v H u H v

v v v v vt mn n m n m

�������������� �

1

1St st cst Sts s z

z z z s

z

Hfu fu v uv v H H H u

s mn s mn mn mn m n m

� ��������������

VA COR StCOR PG

v

s mn

����������������������������������������������������� ���� ������������������������������������������

' '

BF BA+RA+BtSt

HVF

ˆ +w

vz z z

z

H H H D v vv w

mn mn mn s H s

�

�������������� �

F FF

+SuSt HM VM FCurv

������������������������������������������������������������������������������� ������ ��������������

Description of Terms ACC = Local AccelerationHA = Horizontal AdvectionVA = Vertical AdvectionCOR = Coriolis ForceStCOR = Stokes-Coriolis ForcePG = Pressure GradientHVF = Horizontal Vortex ForceBF = Body ForceBA+RA+BuSt+SuSt = Breaking Acceleration+ Roller Acceleration+

Bottom Streaming+ Surface StreamingHM = Horizontal MixingVM = Vertical MixingFcurv = Curvilinear 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-processor 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 coupling and only produces one exe COAWSTM.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 Hwave to

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 NESTING 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/Include/cppdefs.h

See cppdefs for a complete list of ROMS options

This list goes on for many many more pages …..

Application example: Sandy1) roms grid

2) masking

3) bathy

4) child grid

5) 3D: BC's (u,v,temp,salt), init, and climatology

6) 2D: BC's (ubar, vbar, zeta) = tides

7) Surface forcing (heat and momentum fluxes)

8) sandy.h and ocean_sandy.in

9) coawst.bash

10) run it- Handout ends here

- More in the online ppt- Classroom tutorial will now follow:

Projects/Sandy/create_sandy_application.m

1) Grid generation tools

Seagrid - matlabhttp://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.mfunction 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 toolssee WRF grid netcdf_load('wrfinput_d01')

figurepcolorjw(XLONG,XLAT,double(1-LANDMASK))hold on% pick 4 corners for roms parent grid% start in lower left and go clockwisecorner_lon=[ -82 -82 -62 -62];corner_lat=[ 28 42 42 28];plot(corner_lon,corner_lat,'g.','markersize',25)%%pick the number of points in the new roms gridnumx=80;numy=64;%% make a matrix of the lons and latsx=[1 numx; 1 numx]; y=[1 1; numy numy];%z=[corner_lon(1) corner_lon(2) corner_lon(4) corner_lon(3)];F = TriScatteredInterp(x(:),y(:),z(:));[X,Y]=meshgrid(1:numx,1:numy);lon=F(X,Y).';%z=[corner_lat(1) corner_lat(2) corner_lat(4) corner_lat(3)];F = TriScatteredInterp(x(:),y(:),z(:));lat=F(X,Y).';plot(lon,lat,'g+')

select 4 corners

1) Grid generation tools%% Call generic grid creation%roms_grid='Sandy_roms_grid.nc';

rho.lat=lat;rho.lon=lon;rho.depth=zeros(size(rho.lon))+100; % for now just make zerosrho.mask=zeros(size(rho.lon)); % for now just make zerosspherical='T';projection='mercator';save temp_jcw33.mat

eval(['mat2roms_mw(''temp_jcw33.mat'',''',roms_grid,''');'])

2) masking – first base it on WRFF = TriScatteredInterp(double(XLONG(:)),double(XLAT(:)), ... double(1-LANDMASK(:)),'nearest');roms_mask=F(lon,lat);figurepcolorjw(lon,lat,roms_mask)ncwrite(roms_grid,'mask_rho',roms_mask);

2) Masking – get coastlineMay also need a coastline, can obtain this here:

http://www.ngdc.noaa.gov/mgg/coast/

lon=coastline(:,1);lat=coastline(:,2);

save coastline.mat lon lat

45

25

-60-84

2) Maskinguse COAWST/Tools/mfiles/mtools/editmask m file

(from Rutgers, but I changed it to use native matlab netcdf)editmask('USeast_grd.nc','coastline.mat')

3) bathymetrymany sources

ETOPO2

LIDAR

Coastal Relief Model

3) bathymetryInterpolate bathy to the variable 'h' located at your grid rho points (lon_rh, lat_rho).load USeast_bathy.matnetcdf_load(roms_grid)h=griddata(h_lon,h_lat,h_USeast,lon_rho,lat_rho);h(isnan(h))=5;figurepcolorjw(lon_rho,lat_rho,h)ncwrite(roms_grid,'h',hnew);

- Bathymetry can be smoothed usinghttp://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

4) Child grid

ref_ratio=3;roms_child_grid='Sandy_roms_grid_ref3.nc';

F=coarse2fine('Sandy_roms_grid.nc','Sandy_roms_grid_ref3.nc', ... ref_ratio,Istr,Iend,Jstr,Jend);Gnames={'Sandy_roms_grid.nc','Sandy_roms_grid_ref3.nc'};[S,G]=contact(Gnames,'Sandy_roms_contact.nc');

4) Child grid

Redo Bathymetry:load USeast_bathy.matnetcdf_load(roms_grid)h=griddata(h_lon,h_lat,h_USeast,lon_rho,lat_rho);figurepcolorjw(lon_rho,lat_rho,h)ncwrite(roms_grid,'h',hnew);

Redo masking% recompute child mask based on WRF masknetcdf_load('wrfinput_d02');F = TriScatteredInterp(double(XLONG(:)),double(XLAT(:)), ... double(1-LANDMASK(:)),'nearest');roms_mask=F(lon_rho,lat_rho);figurepcolorjw(lon_rho,lat_rho,roms_mask)

5) 3D BC's (u,v,temp,salt), init, and clima. Projects/Sandy/roms_master_climatology_sandy.m

This works for multiple days.

Needs nctoolbox to acess data via thredds

server.

http://code.google.com/p/nctoolbox/

5) 3D BC's (u,v,temp,salt), init, and clima.

% I copied Tools/mfiles/roms_clm/roms_master_climatology_coawst_mw.m

% to Projects/Sandy/roms_master_climatology_sandy.m and ran it:

roms_master_climatology_sandy

% this created three files:

% merged_coawst_clm.nc

% merged_coawst_bdy.nc

% coawst.ini.nc

% I renamed those to Sandy_clm.nc, Sandy_bdy.nc, and Sandy_ini.nc.

%

5) For child grid need init and clim.

- Init for child you can use

create_roms_child_init

For child clim you can use

create_roms_child_clm

6) 2D: BC's (ubar, vbar, zeta) = tides

6) 2D: BC's (ubar, vbar, zeta) = tides 1) Get the tidal data atsvn checkout https://coawstmodel.sourcerepo.com/coawstmodel/data .2) edit Tools/mfiles/tides/create_roms_tides

6) 2D: BC's (ubar, vbar, zeta) = tides

netcdf_load('Sandy_roms_grid.nc')pcolorjw(lon_rho,lat_rho,squeeze(tide_Eamp(:,:,1)))

M2 tidal amplitude

7) Surface forcings (wind stress only)- narr2romsnc.m

COAWST/Tools/mfiles/mtools/narr2romsnc creates netcdf

forcing files for ROMS.

Many others tools available.

Can also use ana_functions.

7) Surface forcings (heat + momentum) create_roms_forcings.m

COAWST/Tools/mfiles/mtools/create_roms_forcings creates

netcdf forcing files for ROMS.

Many others tools available.

8) sandy.h

8) sandy_ocean.in

8) sandy_ocean.in

8) sandy_ocean.in

8) sandy_ocean.in

8) sandy_ocean.in

8) sandy_ocean.in

8) sandy_ocean.in

9) coawst.bash

9) coawst.bash

10) run_file

Output

It’s that easy. I don’t understand why people have problems.

sustr temp (surface)