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 |http://swan.tudelft.nl].
Elements from the SWAN input file are refered to by INPUT*, elements from the SWAN Fortran code swanmain.for are referred to by OV*IVTYPE.

{toc}

h3. SWAN netCDF-CF CDL scheme 

{code}
// A working draft proposal for CF compliance for netCDF output for SWAN
NetCDF SWAN.nc {

// proposal for CF and SWAN meta data in SWAN

dimensions:
	time      = 1; // time:		also put time in for single times
	mx        = 2; // yx:		(mxc+1) for 2D grids
	my        = 3; // xc:		(myc+1) for 2D grids
	md direction  = 4; // nd: (mdc+1) directions, now called nf90_def_dim
	ms frequency  = 5; // ms: (msc+1) frequencies
	locpoints    = 6; // points:	for 1D grids, for UNSTRUC and for squeezed [mx by my] grids

variables:
// dimensions consistent with ncBrowse, not with native MATLAB netcdf package.
// ----------------- COORDINATES -----------------
// Options:
// * like SWAN use same variable for CARTESIAN and SPHERICAL, but change attributes
// * use different variables for CARTESIAN and SPHERICAL, but change attributes
// if INPUT.CGRID.REGular
	double mx(mx), shape        = [2]
		 ;
		mx(mx):swan_xpc     = // INPUT value: optional for input, implemented in output
		mx(mx):swan_xlenc   = // INPUT value: optional for input, implemented in output
		mx(mx):swan_alpc    = // INPUT value: optional for input, implemented in output
		mx(mx):swan_comment = "mxc+1"
		mx(mx):_FillValue   = // INPUT.CGRID.xexc or OVEXCV{IVTYPE}
		mx:actual_range     = [~ ~]
		// if INPUT.CGRID.CARTESIAN
		mx:standard_name    = "projected_x_coordinate"
		mx:units            = "m"
		mx(mx):grid_mapping = "projected_coordinate_system"
		// elseif INPUT.CGRID.SPHERICAL
		mx:standard_name    = "longitude"
		mx:units            = "degrees_east"
		mx(mx):grid_mapping = "wgs84"
		// end
		...
	double my(my), shape        = [3] ;
		my(my):swan_ypc     = // INPUT value: optional for input, implemented in output
		my(my):swan_ylenc   = // INPUT value: optional for input, implemented in output
		my(my):swan_alpc    = // INPUT value: optional for input, implemented in output
		my(my):swan_comment = "myc+1"
		my(my):_FillValue   = // INPUT.CGRID.yexc or OVEXCV{IVTYPE}
		my:actual_range     = [~ ~]
		// if INPUT.CGRID.CARTESIAN
		my:standard_name    = "projected_y_coordinate"
		my:units            = "m"
		my(my):grid_mapping = "projected_coordinate_system"
		// elseif INPUT.CGRID.SPHERICAL
		my:standard_name    = "latitude"
		my:units            = "degrees_north"
		my(my):grid_mapping = "wgs84"
		// end
		...
// - - - - - - - - - - - - - - - - - - - - - - - - - - -
// elseif INPUT.CGRID.CURVilinear
	double XP(mxxc,myyc), shape = [2] ;
		// idem
		...
	double YP(mxxc,myyc), shape = [3] ;
		// idem
		...
// - - - - - - - - - - - - - - - - - - - - - - - - - - -
// elseif INPUT.CGRID.UNSTRUCtured
	double XPx(locpoints), shape = [6] ;
		// idem
		...
	double YPYyP(locpoints), shape = [6] ;
		// idem
		...
// end
// ----------------- DIRECTIONS -----------------
	double CDIRspread_1d(md), shape = [4] ;
		CDIRspread_1d:standard_name    = ""
		CDIRspread_1d:units            = "degrees_true"
		CDIRspread_1d:longstandard_name        = "spectral Cartesian direction"
		CDIR.dir1sea_surface_wave_from_direction" // sea_surface_wave_to_direction
		spread_1d:nautical         =    =1 // INPUTor value:0
 optional for input, implemented in output
		CDIR.dir2  spread_1d.dir1             = // INPUT value: optional for input, implemented in output
		CDIR:swan_commentspread_1d.dir2      = "mdc+1"
		...
	double NDIR(), shape = [4]
		NDIR:standard_name  = // = ""
		NDIR:units      INPUT value: optional for input, implemented in output
		spread_1d:swan_comment      = "degrees_truemdc+1"
		CDIR:long_name        = "spectral nautical direction"
		NDIR.dir1...
// ----------------- FREQUENCY -----------------
	double frequency(ms) ;
		frequency:standard_name    = "wave_frequency"
		frequency:long_name        = "frequencies" // absolute vs relative, see attribute 'relative_to_current' of energy
		frequency:units            = "s-1"
		frequency.swan_flow        = // INPUT value: optional for input, implemented in output
		NDIR.dir2  frequency.swan_fhigh           = // INPUT value: optional for input, implemented in output
		NDIRfrequency:swan_comment     = "mdcmsc+1"
		...
// ----------------- FREQUENCYCOORDINATE SYSTEMS -----------------
	double AFREQ(), shape = [5]
		AFREQ:standard_name    = ""
		AFREQ:long_name        = "absolute frequencies"
		AFREQ:units            = "degrees_true"
		AFREQ.swan_flow        = // INPUT value: optional for input, implemented in output
		AFREQ.swan_fhigh       = // INPUT value: optional for input, implemented in output
		AFREQ:swan_comment     = "msc+1"
		...
	double NFREQ(), shape = [5]
		NFREQ:standard_name    = ""
		NFREQ:long_name        = "relative frequencies"
		NFREQ:units            = "degrees_true"
		NFREQ.swan_flow        = // INPUT value: optional for input, implemented in output
		NFREQ.swan_fhigh// The projected_coordinate_system information could optionally be added to
// either SWAN input or in a post-processing step.
// if INPUT.CGRID.CARTESIAN
//	int32 projected_coordinate_system() ;
//		projected_coordinate_system:name = "Amersfoort / RD New"
//		projected_coordinate_system:epsg = 28992
//		projected_coordinate_system:epsg_name = "Oblique Stereographic"
//		projected_coordinate_system:grid_mapping_name = " "
//		projected_coordinate_system:semi_major_axis = 6.3774e+006
//		projected_coordinate_system:semi_minor_axis = 6.35608e+006
//		projected_coordinate_system:inverse_flattening = 299.153
//		projected_coordinate_system:latitude_of_projection_origin = 52.0922
//		projected_coordinate_system:longitude_of_projection_origin = 5.23155
//		projected_coordinate_system:false_easting = 155000
//		projected_coordinate_system:false_northing = 463000
//		projected_coordinate_system:scale_factor_at_projection_origin = 0.999908
//               = // INPUToptional value:PROJ4 optionalREQUIRED for input, implemented in output
		NFREQ:swan_comment     = "msc+1"
		...
// ----------------- COORDINATE SYSTEMS -----------------
// The projected_coordinate_system information could optionally be added to
// either SWAN input or in a post-processing step.
// if INPUT.CGRID.CARTESIAN
//	int32 projected_coordinate_system([]), shape = [1]
//		epsg:name = "Amersfoort / RD New"
//		epsg:epsg = 28992
//		epsg:epsg_name = "Oblique Stereographic"
//		epsg:grid_mapping_name = " "
//		epsg:semi_major_axis = 6.3774e+006
//		epsg:semi_minor_axis = 6.35608e+006
//		epsg:inverse_flattening = 299.153
//		epsg:latitude_of_projection_origin = 52.0922
//		epsg:longitude_of_projection_origin = 5.23155
//		epsg:false_easting = 155000
//		epsg:false_northing = 463000
//		epsg:scale_factor_at_projection_origin = 0.999908
//FOR ADAGUC.KNMI.NL
//		projected_coordinate_system:proj4_params = "+proj=sterea +lat_0=52.15616055555555 +lon_0=5.38763888888889 +k=0.999908 +x_0=155000 +y_0=463000 +ellps=bessel +units=m +towgs84=565.4174,50.3319,465.5542,-0.398957388243134,0.343987817378283,-1.87740163998045,4.0725 +no_defs"
//		projected_coordinate_system:EPSG_code = "EPSG:28992"
//		projected_coordinate_system:projection_name = "Dutch rijksdriekhoek system"
// - - - - - - - - - - - - - - - - - - - - - - - - - - -
// elseif INPUT.CGRID.SPHERICAL
// The (lat,lon) coordinates information could be hard-coded into SWAN
// with each of the options: CCM, QC or REPEATING
		int32 wgs84() ;
		wgs84:name = "WGS 84"
		wgs84:epsg = 4326
		wgs84:grid_mapping_name = "latitude_longitude"
		wgs84:semi_major_axis = 6.37814e+006
		wgs84:semi_minor_axis = 6.35675e+006
		wgs84:inverse_flattening = 298.257
                // optional PROJ4 REQUIRED FOR ADAGUC.KNMI.NL
//			epsgwgs84:proj4_params = "+proj=sterealonglat +lat_0=52.15616055555555ellps=WGS84 +lon_0=5.38763888888889 +k=0.999908 +x_0=155000 +y_0=463000 +ellps=bessel +units=m +towgs84=565.4174,50.3319,465.5542,-0.398957388243134,0.343987817378283,-1.87740163998045,4.0725 +no_defs"
//		epsg:EPSG_code = "EPSG:28992"
//		epsg:projection_name = "Dutch rijksdriekhoek system"
// - - - - - - - - - - - - - - - - - - - - - - - - - - -
// elseif INPUT.CGRID.SPHERICAL
// The (lat,lon) coordinates information could be hard-coded into SWAN
// with each of the options: CCM, QC or REPEATING
		int32 wgs84([]), shape = [1]
		wgs84:name = "WGS 84"
		wgs84:epsg = 4326
		wgs84:grid_mapping_name = "latitude_longitude"
		wgs84:semi_major_axis = 6.37814e+006
		wgs84:semi_minor_axis = 6.35675e+006
		wgs84:inverse_flattening = 298.257
    datum=WGS84 +no_defs "
		wgs84:EPSG_code = "EPSG:4326"
		wgs84:projection_name = "Latitude Longitude"
		wgs84:wkt = "GEOGCS["WGS 84",...
// end
// ----------------- PRIMARY VARIABLES -----------------
	single density(), shape = [~ ~] // density_1d for 1D, density for 2D
		density:relative_to_current   = 0 // or 1, depending on respectively. AFREQ vs RFREQ
		density:swan_code             =            // OVKEYW{IVTYPE} = 'VaDens';
		density:swan_name             =            // optional PROJ4 REQUIRED FOR ADAGUC.KNMI.NLOVSNAM{IVTYPE} = 'VaDens';
		wgs84density:proj4_params = "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs "
		wgs84:EPSG_code = "EPSG:4326"
		wgs84:projection_name = "Latitude Longitude"
		wgs84:wkt = "GEOGCS["WGS 84",
// end
// ----------------- PRIMARY VARIABLES -----------------
	single VaDens(), shape = [~ ~]
		VaDens:swan_codelong_name             =            // OVLNAM{IVTYPE} = 'spectral variance density';
		density:swan_units            =            // OVUNIT{IVTYPE} =            // OVKEYW{IVTYPE} = 'VaDens''m2/Hz';
		VaDensdensity:swan_namevalid_range(1)             =            // OVSNAMOVLEXP{IVTYPE} = 'VaDens'0.;
		VaDensdensity:long_namevalid_range(2)             =            // OVLNAMOVHEXP{IVTYPE} = 'spectral variance density'100.;
		VaDensdensity:swan_unitsFillValue            =            // OVUNITOVEXCV{IVTYPE} = 'm2/Hz';
		VaDens:valid_range(1)        =            // OVLEXP{IVTYPE} = 0.;
		VaDens:valid_range(2)-99.;
// - - - - - - - - - - - - - - - - - - - - - - - - - - -
		density:units                 =            // OVHEXPOVCFUD{IVTYPE} = 100.;
		VaDens:_FillValue    ''; NEW TABLE NEEDED INSIDE SWAN
		density:standard_name         =            // OVEXCVOVCFSN{IVTYPE} = -99.;
''; NEW TABLE NEEDED INSIDE SWAN
		// -these do -not -need -to -be -mapped - - - - - - - - - - - - - - - - - - - - -
		VaDens:units            // OVSVTY{IVTYPE} = 5;     // means vector, scalar etc.
		// these do not need to be mapped     =            // OVCFUDOVLLIM{IVTYPE} = ''0.; NEW TABLE NEEDED INSIDE SWAN
		VaDens:standard_name         =   // print width for ascii output
		// these do not need to be mapped         // OVCFSNOVULIM{IVTYPE} = ''1000.; NEW TABLE NEEDED INSIDE SWAN
		// print width for ascii output
// these- do- not- need- to- be- mapped- - - - - - - - - // OVSVTY{IVTYPE} = 5;     // means vector, scalar etc.
		// these do not need to be mapped   - - - - - - - - - - - -
		density:actual_range          = [~ ~]      // OVLLIM{IVTYPE} = 0.;    // print width for ascii output
		// these do not need to be mappedadd optionally as extra service to user
		density:coordinates           = "XP YP"   // OVULIM{IVTYPE} = 1000.; // print width for ascii output

		// - - - - - - - - - - - - - - - - - - - - - - - - - - -
		VaDens:actual_rangeif INPUT.CGRID.CARTESIAN
		density():grid_mapping        = "projected_coordinate_system"
		// elseif INPUT.CGRID.SPHERICAL
		density():grid_mapping          = [~ ~]      // add optionally as extra service to user
		VaDens:coordinates           = "XP YP"    //
		// if INPUT.CGRID.CARTESIAN
		VaDens():grid_mapping        = "projected_coordinate_system"
		// elseif INPUT.CGRID.SPHERICAL
		VaDens():grid_mapping        = "wgs84"
		// end
// ----------------- GLOBAL META_DATA -----------------
//global Attributes:
		:title = "INPUT.PROJECT.name,INPUT.PROJECT.nr"
		:institution"wgs84"
		// end
// ----------------- GLOBAL META_DATA -----------------
//global Attributes:
		:title = "INPUT.PROJECT.name,INPUT.PROJECT.nr"
		:institution = ""
		:source = ""
		:history = "Data produced by SWAN version 40.72AB"
		:references = ""
		:email = ""
		:comment = "INPUT.PROJECT.title1,INPUT.PROJECT.title2,INPUT.PROJECT.title3"
		:version = ""
		:sourceConventions = "CF-1.5"
		:historyCF:featureType = "Data produced by SWAN version 40.72AB"
		:references = ""
		:email = ""
		:comment = "INPUT.PROJECT.title1,INPUT.PROJECT.title2,INPUT.PROJECT.title3"
		:version = "Grid"
		:terms_of_use = "These data can be used freely for research purposes provided that the following source is acknowledged: institution"
		:Conventionsdisclaimer = "CF-1.5"
		:CF:featureType = "Grid"
		:terms_for_use = "These data can be used freely for research purposes provided that the following source is acknowledged: institution"
		:disclaimer = "This data This data is made available in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE."
}
{code}

h3. Mapping of SWAN names to CF standard names 

For the complete list where we have to get names from, or have them added to is: [http://cf-pcmdi.llnl.gov/documents/cf-standard-names/]
This table is under construction, please fill in any missing UD units or CF standard names.

|| OVKEYW || OVSNAM || OVLNAM                        || OVUNIT || OVLLIM    || OVULIM   ||    OVEXCV || new: OVCFUD (UD units)||new: OVCFSN (standard name)||
|XP    |Xp      |X user coordinate                        |UL   |-10000000000|10000000000|-10000000000| m| projection_x_coordinate,longitude|
|YP    |Yp      |Y user coordinate                        |UL   |-10000000000|10000000000|-10000000000| m| projection_y_coordinate,latitude|
|DIST  |Dist    |distance along output curve              |UL   |           0|10000000000|         -99| m| |
|DEP   |Depth   |Depth                                    |UH   |        -100|        100|         -99| m| |
|VEL   |Vel     |Current velocity                         |UV   |          -2|          2|           0| m/s| |
|UBOT  |Ubot    |Orbital velocity at the bottom           |UV   |           0|          1|         -10| | |
|DISS  |Dissip  |Energy dissipation                       |m2/s |           0|        0.1|          -9| | |
|QB    |Qb      |Fraction breaking waves                  |     |           0|          1|          -1| | |
|LEA   |Leak    |Energy leak over spectral boundaries     |m2/s |           0|        100|          -9| | |
|HS    |Hsig    |Significant wave height                  |UH   |           0|         10|          -9| | sea_surface_wave_significant_height|
|TM01  |Tm01    |Average absolute wave period             |UT   |           0|        100|          -9| | |
|RTP   |RTpeak  |Relative peak period                     |UT   |           0|        100|          -9| | |
|DIR   |Dir     |Average wave direction                   | UDI |           0|        360|        -999| degrees_true _if nautical_| sea_surface_wave_from_direction|
|PDI   |PkDir   |direction of the peak of the spectrum    | UDI |           0|        360|        -999| | |
|TDI   |TDir    |direction of the energy transport        | UDI |           0|        360|        -999| | |
|DSPR  |Dspr    |directional spreading                    | UDI |           0|         60|          -9| | |
|WLEN  |Wlen    |Average wave length                      |UL   |           0|        200|          -9| | |
|STEE  |Steepn  |Wave steepness                           |     |           0|        0.1|          -9| | |
|TRA   |Transp  |Wave energy transport                    |m3/s |         -10|         10|           0| | |
|FOR   |WForce  |Wave driven force per unit surface       |UF   |         -10|         10|           0| | |
|AAAA  |AcDens  |spectral action density                  |m2s  |           0|        100|         -99| | |
|EEEE  |EnDens  |spectral energy density                  |m2   |           0|        100|         -99| | |
|AAAA  |Aux     |auxiliary variable                       |     |-10000000000|10000000000|-10000000000| | |
|XC    |Xc      |X computational grid coordinate          |     |           0|        100|          -9| | |
|YC    |Yc      |Y computational grid coordinate          |     |           0|        100|          -9| | |
|WIND  |Windv   |Wind velocity at 10 m above sea level    |UV   |         -50|         50|           0| | |
|FRC   |FrCoef  |Bottom friction coefficient              |     |           0|          1|          -9| | |
|RTM01 |RTm01   |Average relative wave period             |UT   |           0|        100|          -9| | |
|EEEE  |EnDens  |energy density integrated over direction |m2   |           0|        100|         -99| | |
|DHS   |dHs     |difference in Hs between iterations      |UH   |           0|          1|          -9| | |
|DRTM01|dTm     |difference in Tm between iterations      |UT   |           0|          2|          -9| | |
|TM02  |Tm02    |Zero-crossing period                     |UT   |           0|        100|          -9| | |
|FSPR  |FSpr    |Frequency spectral width {Kappa}         |     |           0|          1|          -9| | |
|URMS  |Urms    |RMS of orbital velocity at the bottom    |UV   |           0|          1|          -9| | |
|UFRI  |Ufric   |Friction velocity                        |UV   |           0|          1|          -9| | |
|ZLEN  |Zlen    |Zero velocity thickness of boundary layer|UL   |           0|          1|          -9| | |
|TAUW  |TauW    |                                         |     |           0|          1|          -9| | |
|CDRAG |Cdrag   |Drag coefficient                         |     |           0|          1|          -9| | |
|SETUP |Setup   |Setup due to waves                       |m    |          -1|          1|          -9| | |
|TIME  |Time    |Date-time                                |     |           0|          1|      -99999| | |
|TSEC  |Tsec    |Time in seconds from reference time      |s    |     -100000|    1000000|      -99999| | |
|PER   |Period  |Average absolute wave period             |UT   |           0|        100|          -9| | |
|RPER  |RPeriod |Average relative wave period             |UT   |           0|        100|          -9| | |
|HSWE  |Hswell  |Wave height of swell part                |UH   |           0|         10|          -9| | |
|URSELL|Ursell  |Ursell number                            |     |           0|          1|          -9| | |
|ASTD  |ASTD    |Air-Sea temperature difference           |K    |         -10|         10|         -99| | |
|TMM10 |Tm_10   |Average absolute wave period             |UT   |           0|        100|          -9| | |
|RTMM10|RTm_10  |Average relative wave period             |UT   |           0|        100|          -9| | |
|DIFPAR|DifPar  |Diffraction parameter                    |     |         -10|         10|         -99| | |
|TMBOT |TmBot   |Bottom wave period                       |UT   |           0|        100|          -9| | |
|WATL  |Watlev  |Water level                              |UH   |        -100|        100|         -99| | |
|BOTL  |Botlev  |Bottom level                             |UH   |        -100|        100|         -99| | |
|TPS   |TPsmoo  |Relative peak period {smooth}            |UT   |           0|        100|          -9| | |
|DISB  |Disbot  |Bottom friction dissipation              |m2/s |           0|        0.1|          -9| | |
|DISSU |Dissrf  |Wave breaking dissipation                |m2/s |           0|        0.1|          -9| | |
|DISW  |Diswcp  |Whitecapping dissipation                 |m2/s |           0|        0.1|          -9| | |
|DISM  |Dismud  |Fluid mud dissipation                    |m2/s |           0|        0.1|          -9| | |
|WLENMR|Wlenmr  |Average wave length with mud real part   |UL   |           0|        200|          -9| | |
|KI    |ki      |Average wave number with mud imag part   |rad/m|           0|          1|          -9| | |
|MUDL  |Mudlayer|Mudlayer thickness                       |UH   |           0|        100|         -99| | |
|VaDens|VaDens  |spectral variance density                |m2/Hz|           0|        100|         -99| m2s| sea_surface_wave_variance_spectral_density|
|Swind |Swind   |wind source term                         |m2   |           0|        100|         -99| | |
|Swcap |Swcap   |whitecapping dissipation                 |m2   |           0|        100|         -99| | |
|Sfric |Sfric   |bottom friction dissipation              |m2   |           0|        100|         -99| | |
|Smud  |Smud    |fluid mud dissipation                    |m2   |           0|        100|         -99| | |
|Ssurf |Ssurf   |surf breaking dissipation                |m2   |           0|        100|         -99| | |
|Snl3  |Snl3    |triad interactions                       |m2   |           0|        100|         -99| | |
|Snl4  |Snl4    |quadruplet interactions                  |m2   |           0|        100|         -99| | |
|KIMAG |KIMAG   |Wave number with mud imag part           |rad/m|         NaN|        NaN|         NaN| | |
|KREAL |KREAL   |Wave number with mud real part           |rad/m|         NaN|        NaN|         NaN| | |

This table was generated with the Matlab code

{code}
[D,D0] = swan_quantity % part of Openearth.eu[addrowcol(char(D0.OVKEYW),0,[-1 1],'|') char(D0.OVSNAM) addrowcol(char(D0.OVLNAM),0,[-1 1],'|') char(D0.OVUNIT) addrowcol(num2str(cell2mat(D0.OVLEXP')),0,[-1 1],'|') addrowcol(num2str(cell2mat(D0.OVHEXP')),0,[1],'|') addrowcol(num2str(cell2mat(D0.OVEXCV')),0,[1],'| | |')]
{code}

using