PRODUCT USER MANUAL - For Arctic Ocean Wave Analysis and Forecasting

PRODUCT USER MANUAL - For Arctic Ocean Wave Analysis and Forecasting

PRODUCT USER MANUAL For Arctic Ocean Wave Analysis and Forecasting Products ARCTIC_ANALYSIS_FORECAST_WAV_002_010 Issue: 1.2 Contributors: Øyvind Saetra, Arild Burud, Ana Carrasco, M. Müller CMEMS version scope : Version 4.0 Approval Date by the CMEMS products team: 12 March 2018

PUM for product ARCTIC_ANALYSIS_FORECAST_WAV Ref: CMEMS-ARC-PUM- WAVE_002_010 Date : 8 Feb. 2018 Issue : 1.2 © EU Copernicus Marine Service – Public Page 2/ 20 CHANGE RECORD Issue Date § Description of Change Author Validated By 1.0 1. Dec 2016 All Creation of the document Øyvind Saetra, Arild Burud, Ana Carrasco L.

Bertino 1.1 17 Mar 2017 All Modified after technical review Ana Carrasco L. Bertino 1.2 8. Feb. 2018 Update to new wave V4 product Malte Müller L. Bertino

PUM for product ARCTIC_ANALYSIS_FORECAST_WAV Ref: CMEMS-ARC-PUM- WAVE_002_010 Date : 8 Feb. 2018 Issue : 1.2 © EU Copernicus Marine Service – Public Page 3/ 20 TABLE OF CONTENTS I INTRODUCTION Erreur ! Signet non défini. I.1 Summary Erreur ! Signet non défini. II DESCRIPTION OF THE PRODUCT SPECIFICATION Erreur ! Signet non défini. II.1 General Information (Real-time product) Erreur ! Signet non défini. II.2 Details of datasets (Real Time product) Erreur ! Signet non défini. II.3 Production System Description Erreur ! Signet non défini. II.3.1 ARCTIC_ANALYSIS_FORECAST_WAVE Erreur ! Signet non défini.

II.4 Update Time Erreur ! Signet non défini. II.5 Time coverage Erreur ! Signet non défini. II.6 Time averaging Erreur ! Signet non défini. III HOW TO DOWNLOAD A PRODUCT Erreur ! Signet non défini. IV files NOMENCLATURE and format Erreur ! Signet non défini. IV.1 Nomenclature of files when downloaded through the CMEMS Web Portal Subsetter Service Erreur ! Signet non défini.

IV.2 Nomenclature of files when downloaded through the CMEMS Web Portal DirectGetFile or CMEMS FTP Service Erreur ! Signet non défini. IV.3 . File Format : NetCDF Erreur ! Signet non défini. IV.4 File size Erreur ! Signet non défini. IV.5 Other information : mean centre of Products, land mask value, missing value Erreur ! Signet non défini. IV.6 Reading Software Erreur ! Signet non défini. IV.7 Structure and semantic of netCDF maps files Erreur ! Signet non défini.

PUM for product ARCTIC_ANALYSIS_FORECAST_WAV Ref: CMEMS-ARC-PUM- WAVE_002_010 Date : 8 Feb.

2018 Issue : 1.2 © EU Copernicus Marine Service – Public Page 4/ 20 GLOSSARY AND ABBREVIATIONS MFC Monitoring and Forecasting Centre ARC_MFC Arctic Monitoring and Forecasting Centre NetCDF Network Common Data Form ECMWF European Centre for Medium-Range Weather Forecasts MET The Norwegian Meteorological Institute

PUM for product ARCTIC_ANALYSIS_FORECAST_WAV Ref: CMEMS-ARC-PUM- WAVE_002_010 Date : 8 Feb. 2018 Issue : 1.2 © EU Copernicus Marine Service – Public Page 5/ 20

PUM for product ARCTIC_ANALYSIS_FORECAST_WAV Ref: CMEMS-ARC-PUM- WAVE_002_010 Date : 8 Feb. 2018 Issue : 1.2 © EU Copernicus Marine Service – Public Page 6/ 20 I INTRODUCTION I.1 Summary This guide describes the data product files from the Arctic Monitoring and Forecasting Centre, what data services are available to access them, and how to use the files and services. ARCTIC_ANALYSIS_FORECAST_WAV_002_010 is the analysis and forecast products of the Arctic Monitoring and Forecast Center for ocean waves.

The system delivers daily forecast of ocean wave data for 5 days ahead. Output from the system is hourly data of significant wave height, wave period and direction (for a list of the full set of parameters see Table 2 below).

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PUM for product ARCTIC_ANALYSIS_FORECAST_WAV Ref: CMEMS-ARC-PUM- WAVE_002_010 Date : 8 Feb. 2018 Issue : 1.2 © EU Copernicus Marine Service – Public Page 8/ 20 II DESCRIPTION OF THE PRODUCT SPECIFICATION II.1 General Information (Real-time product) Product Lines ARCTIC_ANALYSIS_FORECAST_WAV Geographical coverage North of 65°N Variables Full list of variable is listed in Table 2 below Analysis From 2016-12-09 ; ongoing Forecast 5 day forecasts Temporal resolution hourly instantaneous surface fields Target delivery time Daily before 14:00 UTC Delivery mechanism CMEMS Information System: DirectGetFile, Subsetter, MFTP and WMS Horizontal resolution 6.25 km (output) Format Netcdf4 Table 1: ARC-MFC Real Time products II.2 Details of datasets (Real Time product) ARCTIC_ANALYSIS_FORECAST_WAV ARCTIC_ANALYSIS_FORECAST_WAV_002_010 dat aset - my wav e- arc- my oce an- be contains all the variables.

VHM0 [m] Spectral significant wave height (Hm0 sea_surface_wave_significant_height VTM10 [s] Spectral moments (-1,0) wave period (Tm-10) sea_surface_wave_mean_period_from_variance_spectral_density_inverse_frequen cy_moment VTM02 [s] Spectral moments (0,2) wave period (Tm02) sea_surface_wave_mean_period_from_variance_spectral_density_second_frequenc y_moment VTPK [s] Wave period at spectral peak / peak period (Tp) sea_surface_wave_period_at_variance_spectral_density_maximum VMDR [degree] Mean wave direction from (Mdir)

PUM for product ARCTIC_ANALYSIS_FORECAST_WAV Ref: CMEMS-ARC-PUM- WAVE_002_010 Date : 8 Feb. 2018 Issue : 1.2 © EU Copernicus Marine Service – Public Page 9/ 20 sea_surface_wave_from_direction VPED [degree] Wave principal direction at spectral peak sea_surface_wave_from_direction_at_spectral_peak VSDX [m s-1] Stokes drift U sea_surface_wave_stokes_drift_x_velocity VSDY [m s-1] Stokes drift V sea_surface_wave_stokes_drift_y_velocity VHM0_WW [m] Spectral significant wind wave height sea_surface_wind_wave_significant_height VTM01_WW [s] Spectral moments (0,1) wind wave period sea_surface_wind_wave_mean_period VMDR_WW [degree] Mean wind wave direction from sea_surface_wind_wave_from_direction VHM0_SW1 [m] Spectral significant primary swell wave height sea_surface_primary_swell_wave_significant_height VTM01_SW1 [s] Spectral moments (0,1) primary swell wave period sea_surface_primary_swell_wave_mean_period VMDR_SW1 [degree] Mean primary swell wave direction from sea_surface_primary_swell_wave_from_direction VHM0_SW2 [m] Spectral significant secondary swell wave height sea_surface_secondary_swell_wave_significant_height VTM01_SW2 [s] Spectral moments (0,1) secondary swell wave period sea_surface_secondary_swell_wave_mean_period VMDR_SW2 [degree] Mean secondary swell wave direction from sea_surface_secondary_swell_wave_from_direction Table 2: List of variables in datasets and their names and units in the NetCDF output files for the ARCTIC_ANALYSIS_FORECAST_WAVE_002_010 II.3 Production System Description II.3.1 ARCTIC_ANALYSIS_FORECAST_WAV The ARCTIC_ANALYSIS_FORECAST_WAV_002_010 is a wave forecast system run at the Norwegian Meteorological Institute (MET) and the core model is based on an upgraded version the European wave model WAM (see link for documentation under subsection 3.1.1: The Model).

It runs

PUM for product ARCTIC_ANALYSIS_FORECAST_WAV Ref: CMEMS-ARC-PUM- WAVE_002_010 Date : 8 Feb. 2018 Issue : 1.2 © EU Copernicus Marine Service – Public Page 10/ 20 once daily producing 5-days forecasts for an area covering the Nordic Seas and the Arctic Ocean. The model is forced by wave spectra from the European Centre for Medium-Range Weather Forecasts (ECMWF) at the lateral boundaries, with surface (10-metre) winds, also from ECMWF, at the surface and with ice concentration from EUMETSAT OSI SAF. The model implementation includes a data assimilation scheme for satellite altimeter data. This is currently not in use due to the lack of altimeter data north of 65 N.

Plans for the next version is to include data assimilation once Sentile-3 altimeter data becomes available.

. . Domain Resolution and grid Geographic coverage All products are calculated in a rotated spherical grid with 8km horizontal resolution. As a post processing these are interpolated to a polar stereographic grid of 6.25km horizontal resolution as shown in Figure 1.The data are delivered to the users through the CMEMS system in the same grid as used for delivering data from the Arctic MFC ocean circulation model. Polar stereographic grid Figure 1 Example of forecast of significant wave height.. Bathymetry Vertical grid surface Spectral grid The horizontal resolution is 8 km and the spectral resolution is 36x36 (directions x frequencies).

Model Version The wave model WAM solves the equations for the conservation of spectral wave energy in the presence of dissipation, wind input and non-linear interaction between spectral wave nodes. The original version was developed by a group of European scientists in the 1980's and was the first third-generation wave model, which does not parametrize the non-linear interaction, but computes this term by a numerical approximation to the exact formulation. The current model version is an upgrade

PUM for product ARCTIC_ANALYSIS_FORECAST_WAV Ref: CMEMS-ARC-PUM- WAVE_002_010 Date : 8 Feb.

2018 Issue : 1.2 © EU Copernicus Marine Service – Public Page 11/ 20 made in the FP7 project MyWave. Documentation for this version of WAM is given in: http://met.no/Forskning/Publikasjoner/MyWave/filestore/MyWave_Report_D1.1.p df Assimilation scheme Data assimilation is currently not in use due to the lack of altimeter data north of 65° N. Plans for the next version is to include data assimilation once Sentinel-3 altimeter data becomes available.

Assimilated observations Ø Initial conditions Forcing and lateral boundary conditions six-hourly analysed U10 wind fields from ECMWF wave spectra from ECMWF Observations The forecasts are contentiously monitored and verified against available buoy and platform observations within the domain. The observations available in Near-Real Time (NRT) MET are all operated by the offshore industry and provided in-kind to the MFC. These consist observing techniques from wave riders to radar and sonar technologies. These are used to produce analysis and forecast scores that are issued in quarterly reports.

Table 3: System Description II.4 Update Time ARCTIC_ANALYSIS_FORECAST_WAV_002_010 products: The daily forecast is available before 14:00 UTC. II.5 Time coverage Model data is available starting from 2016-12-09 and ongoing, up to the latest 5 day forecast. When using the Subsetter and DirectGetFile interface, user will get the “best estimate” for each day. II.6 Time averaging The fields are 1-hourly instantaneous

PUM for product ARCTIC_ANALYSIS_FORECAST_WAV Ref: CMEMS-ARC-PUM- WAVE_002_010 Date : 8 Feb. 2018 Issue : 1.2 © EU Copernicus Marine Service – Public Page 12/ 20 III HOW TO DOWNLOAD A PRODUCT To download products from the Copernicus Marine Environment Monitoring Service (CMEMS) you first need to register as a user.

How to register (FAQ1) and the process and download products (FAQ3) is described in detail at: http://marine.copernicus.eu/services-portfolio/technical-faq/#1

PUM for product ARCTIC_ANALYSIS_FORECAST_WAV Ref: CMEMS-ARC-PUM- WAVE_002_010 Date : 8 Feb. 2018 Issue : 1.2 © EU Copernicus Marine Service – Public Page 13/ 20 IV FILES NOMENCLATURE AND FORMAT The nomenclature of the downloaded files differs on the basis of the chosen download mechanism Subsetter or Directgetfile or MFTP service. IV.1 Nomenclature of files when downloaded through the CMEMS Web Portal Subsetter Service Files nomenclature when downloaded through the CMEMS Web Portal Subsetter is based on product dataset name and a numerical reference related to the request number in the MIS-GW (MET-GW).

The scheme is: datasetname_nnnnnn.nc where : datasetname is a character string with the following : ● dataset-mywave-arctic-be nnnnnn: 6 digit integer corresponding to the unique request number in the MET-GW. .nc: standard NetCDF filename extension.

Example: dataset-mywave-arctic -be_435283.nc IV.2 Nomenclature of files when downloaded through the CMEMS Web Portal DirectGetFile or CMEMS FTP Service Files nomenclature when downloaded through the CMEMS Web Portal DirectGetFile is based on product dataset name and a numerical reference related to the request number in the MIS-GW (MET- GW). The scheme is: datasetname_nnnnnn.zip where : datasetname is a character string with the following : • dataset-mywave-arctic-be nnnnnn: 6 digit integer corresponding to the unique request number in the MET-GW. .zip: standard ZIP filename extension.

Example: dataset-mywave-arctic -be_435284.zip The downloaded ZIP file will contain files named in the following scheme: [VDATE]_MyWaveWam8_b[BDATE].nc where [BDATE]: YYYYMMDD is the bulletin date [VDATE]: YYYYMMDD is the forecast valid date When downloading through the CMEMS MFTP service, users may select files individually, where filenames are [VDATE]_MyWaveWam8_b[BDATE].nc as described above.

PUM for product ARCTIC_ANALYSIS_FORECAST_WAV Ref: CMEMS-ARC-PUM- WAVE_002_010 Date : 8 Feb. 2018 Issue : 1.2 © EU Copernicus Marine Service – Public Page 14/ 20 Example: 20170108_MyWaveWam8_b20170104.nc is the file containing the hourly values for 2017-01-08 00:00-23:00 UTC, coming from the bulletin of 2017-01-04.IV.3 . File Format : NetCDF The products are stored using the NetCDF format. NetCDF (network Common Data Form) is an interface for array-oriented data access and a library that provides an implementation of the interface. The netCDF library also defines a machine-independent format for representing scientific data.

Together, the interface, library, and format support the creation, access, and sharing of scientific data. The netCDF software was developed at the Unidata Program Center in Boulder, Colorado. The netCDF libraries define a machine-independent format for representing scientific data.

Please see Unidata netCDF pages (http://www.unidata.ucar.edu/software/netcdf/) for more information, and to retrieve netCDF software package. NetCDF data format is: * Self-Describing. A netCDF file includes information about the data it contains. * Architecture-independent. A netCDF file is represented in a form that can be accessed by computers with different ways of storing integers, characters, and floating-point numbers. * Direct-access. A small subset of a large dataset may be accessed efficiently, without first reading through all the preceding data.

* Appendable. Data can be appended to a netCDF dataset along one dimension without copying the dataset or redefining its structure.

The structure of a netCDF dataset can be changed, though this sometimes causes the dataset to be copied. * Sharable. One writer and multiple readers may simultaneously access the same netCDF file. The products are compliant with the NetCDF Climate and Forecast Convention CF-1.4 (see http://cf- pcmdi.llnl.gov/). IV.4 File size DATASET NAME NAME OF FILE DIMENSION [MB] Compressed Uncompresse d dataset-mywave- arc-myocean-be 5 files with name: [VDATE]_MyWaveWam8_b[BDATE]. nc, Where VDATE and BDATE are explained in section IV.2 5 * 117M 5 * 117M* *: The size of NetCDF4 files does not change with compression.

IV.5 Other information: mean centre of Products, land mask value, missing value ARCTIC_ANALYSIS_FORECAST_WAV_002_010 data are fields of hourly instantaneous values

PUM for product ARCTIC_ANALYSIS_FORECAST_WAV Ref: CMEMS-ARC-PUM- WAVE_002_010 Date : 8 Feb. 2018 Issue : 1.2 © EU Copernicus Marine Service – Public Page 15/ 20 Fill values / missing values: -999.f, for all variables. This value is also used where there is land or ice cover. An extra ice mask variable ICE_MASK is available to make it possible to identify the ice coverage, it contains the value 0.f for open water, 1.f for ice covered water or -999.f (“Fillvalue”) for land cover. IV.6 Reading Software NetCDF data can be browsed and used through a number of software packages, including: ✓ ncBrowse: http://www.epic.noaa.gov/java/ncBrowse/, ✓ NetCDF Operator (NCO): http://nco.sourceforge.net/ ✓ IDL, Matlab, Panoply, GMT… IV.7 Structure and semantic of netCDF maps files For ARCTIC_ANALYSIS_FORECAST_WAV_002_010 product: The model output files contain some additional fields in addition to the variables mentioned earlier.

An example output NetCDF file header is inserted below, with the additional fields in italic fonts. netcdf \20180217_MyWaveWam8r625_b20180207 { dimensions: time = UNLIMITED ( 1 currently) rlat = 1761 ; rlon = 1217 ; variables: float ICE_MASK(time, rlat, rlon) ; ICE_MASK:_FillValue = -999.f ; ICE_MASK:long_name = "0 = water, 1=ice" ; ICE_MASK:metno_name = "ICE_MASK" ; ICE_MASK:units = "1" ; ICE_MASK:coordinates = "lon lat" ; ICE_MASK:grid_mapping = "projection_stere" ; float VHM0(time, rlat, rlon) ; VHM0:_FillValue = -999.f ; VHM0:long_name = "Spectral significant wave height (Hm0)" ; VHM0:standard_name = "sea_surface_wave_significant_height" ; VHM0:units = "m" ; VHM0:coordinates = "lon lat" ; VHM0:grid_mapping = "projection_stere" ;

PUM for product ARCTIC_ANALYSIS_FORECAST_WAV Ref: CMEMS-ARC-PUM- WAVE_002_010 Date : 8 Feb. 2018 Issue : 1.2 © EU Copernicus Marine Service – Public Page 16/ 20 float VHM0_SW1(time, rlat, rlon) ; VHM0_SW1:_FillValue = -999.f ; VHM0_SW1:long_name = "Spectral significant primary swell wave height" ; VHM0_SW1:standard_name = "sea_surface_primary_swell_wave_significant_height" ; VHM0_SW1:units = "m" ; VHM0_SW1:coordinates = "lon lat" ; VHM0_SW1:grid_mapping = "projection_stere" ; float VHM0_SW2(time, rlat, rlon) ; VHM0_SW2:_FillValue = -999.f ; VHM0_SW2:long_name = "Spectral significant secondary swell wave height" ; VHM0_SW2:standard_name = "sea_surface_secondary_swell_wave_significant_height" ; VHM0_SW2:units = "m" ; VHM0_SW2:coordinates = "lon lat" ; VHM0_SW2:grid_mapping = "projection_stere" ; float VHM0_WW(time, rlat, rlon) ; VHM0_WW:_FillValue = -999.f ; VHM0_WW:long_name = "Spectral significant wind wave height" ; VHM0_WW:standard_name = "sea_surface_wind_wave_significant_height" ; VHM0_WW:units = "m" ; VHM0_WW:coordinates = "lon lat" ; VHM0_WW:grid_mapping = "projection_stere" ; float VMDR(time, rlat, rlon) ; VMDR:_FillValue = -999.f ; VMDR:long_name = "Mean wave direction from (Mdir)" ; VMDR:standard_name = "sea_surface_wave_from_direction" ; VMDR:units = "degree" ; VMDR:coordinates = "lon lat" ; VMDR:grid_mapping = "projection_stere" ; float VMDR_SW1(time, rlat, rlon) ; VMDR_SW1:_FillValue = -999.f ; VMDR_SW1:long_name = "Mean primary swell wave direction from" ; VMDR_SW1:standard_name = "sea_surface_primary_swell_wave_from_direction" ; VMDR_SW1:units = "degree" ; VMDR_SW1:coordinates = "lon lat" ; VMDR_SW1:grid_mapping = "projection_stere" ; float VMDR_SW2(time, rlat, rlon) ; VMDR_SW2:_FillValue = -999.f ; VMDR_SW2:long_name = "Mean secondary swell wave direction from" ;

PUM for product ARCTIC_ANALYSIS_FORECAST_WAV Ref: CMEMS-ARC-PUM- WAVE_002_010 Date : 8 Feb. 2018 Issue : 1.2 © EU Copernicus Marine Service – Public Page 17/ 20 VMDR_SW2:standard_name = "sea_surface_secondary_swell_wave_from_direction" ; VMDR_SW2:units = "degree" ; VMDR_SW2:coordinates = "lon lat" ; VMDR_SW2:grid_mapping = "projection_stere" ; float VMDR_WW(time, rlat, rlon) ; VMDR_WW:_FillValue = -999.f ; VMDR_WW:long_name = "Mean wind wave direction from" ; VMDR_WW:standard_name = "sea_surface_wind_wave_from_direction" ; VMDR_WW:units = "degree" ; VMDR_WW:coordinates = "lon lat" ; VMDR_WW:grid_mapping = "projection_stere" ; float VPED(time, rlat, rlon) ; VPED:_FillValue = -999.f ; VPED:long_name = "Wave principal direction at spectral peak" ; VPED:standard_name = "sea_surface_wave_from_direction_at_spectral_peak" ; VPED:units = "degree" ; VPED:coordinates = "lon lat" ; VPED:grid_mapping = "projection_stere" ; float VSDX(time, rlat, rlon) ; VSDX:_FillValue = -999.f ; VSDX:long_name = "Stokes drift U" ; VSDX:standard_name = "sea_surface_wave_stokes_drift_x_velocity" ; VSDX:units = "m/s" ; VSDX:coordinates = "lon lat" ; VSDX:grid_mapping = "projection_stere" ; float VSDY(time, rlat, rlon) ; VSDY:_FillValue = -999.f ; VSDY:long_name = "Stokes drift V" ; VSDY:standard_name = "sea_surface_wave_stokes_drift_y_velocity" ; VSDY:units = "m/s" ; VSDY:coordinates = "lon lat" ; VSDY:grid_mapping = "projection_stere" ; float VTM01_SW1(time, rlat, rlon) ; VTM01_SW1:_FillValue = -999.f ; VTM01_SW1:long_name = "Spectral moments (0,1) primary swell wave period" ; VTM01_SW1:standard_name = "sea_surface_primary_swell_wave_mean_period" ; VTM01_SW1:units = "s" ; VTM01_SW1:coordinates = "lon lat" ; VTM01_SW1:grid_mapping = "projection_stere" ;

PUM for product ARCTIC_ANALYSIS_FORECAST_WAV Ref: CMEMS-ARC-PUM- WAVE_002_010 Date : 8 Feb. 2018 Issue : 1.2 © EU Copernicus Marine Service – Public Page 18/ 20 float VTM01_SW2(time, rlat, rlon) ; VTM01_SW2:_FillValue = -999.f ; VTM01_SW2:long_name = "Spectral moments (0,1) secondary swell wave period" ; VTM01_SW2:standard_name = "sea_surface_secondary_swell_wave_mean_period" ; VTM01_SW2:units = "s" ; VTM01_SW2:coordinates = "lon lat" ; VTM01_SW2:grid_mapping = "projection_stere" ; float VTM01_WW(time, rlat, rlon) ; VTM01_WW:_FillValue = -999.f ; VTM01_WW:long_name = "Spectral moments (0,1) wind wave period" ; VTM01_WW:standard_name = "sea_surface_wind_wave_mean_period" ; VTM01_WW:units = "s" ; VTM01_WW:coordinates = "lon lat" ; VTM01_WW:grid_mapping = "projection_stere" ; float VTM02(time, rlat, rlon) ; VTM02:_FillValue = -999.f ; VTM02:long_name = "Spectral moments (0,2) wave period (Tm02)" ; VTM02:standard_name = "sea_surface_wave_mean_period_from_variance_spectral_density_second_frequen cy_moment" ; VTM02:units = "s" ; VTM02:coordinates = "lon lat" ; VTM02:grid_mapping = "projection_stere" ; float VTM10(time, rlat, rlon) ; VTM10:_FillValue = -999.f ; VTM10:long_name = "Spectral moments (-1,0) wave period (Tm-10)" ; VTM10:standard_name = "sea_surface_wave_mean_period_from_variance_spectral_density_inverse_freque ncy_moment" ; VTM10:units = "s" ; VTM10:coordinates = "lon lat" ; VTM10:grid_mapping = "projection_stere" ; float VTPK(time, rlat, rlon) ; VTPK:_FillValue = -999.f ; VTPK:long_name = "Wave period at spectral peak / peak period (Tp)" ; VTPK:standard_name = "sea_surface_wave_period_at_variance_spectral_density_maximum" ; VTPK:units = "s" ; VTPK:coordinates = "lon lat" ; VTPK:grid_mapping = "projection_stere" ; double forecast_reference_time ; forecast_reference_time:standard_name = "forecast_reference_time" ;

PUM for product ARCTIC_ANALYSIS_FORECAST_WAV Ref: CMEMS-ARC-PUM- WAVE_002_010 Date : 8 Feb. 2018 Issue : 1.2 © EU Copernicus Marine Service – Public Page 19/ 20 forecast_reference_time:units = "days since 1970-01-01 00:00:00 +00:00" ; double lat(rlat, rlon) ; lat:units = "degree_north" ; lat:long_name = "latitude" ; lat:standard_name = "latitude" ; double lon(rlat, rlon) ; lon:units = "degree_east" ; lon:long_name = "longitude" ; lon:standard_name = "longitude" ; float model_depth(rlat, rlon) ; model_depth:_FillValue = -999.f ; model_depth:long_name = "water depth" ; model_depth:standard_name = "sea_floor_depth_below_sea_level" ; model_depth:units = "m" ; model_depth:coordinates = "lon lat" ; model_depth:grid_mapping = "projection_stere" ; int projection_stere ; projection_stere:grid_mapping_name = "polar_stereographic" ; projection_stere:scale_factor_at_projection_origin = 1.

; projection_stere:straight_vertical_longitude_from_pole = -45. ; projection_stere:latitude_of_projection_origin = 90. ; projection_stere:earth_radius = 6371000. ; projection_stere:proj4 = "+proj=stere +lon_0=-45 +lat_0=90 +k=1 +R=6371000 +no_defs" ; double rlat(rlat) ; rlat:axis = "Y" ; rlat:standard_name = "projection_y_coordinate" ; rlat:units = "m" ; double rlon(rlon) ; rlon:axis = "X" ; rlon:standard_name = "projection_x_coordinate" ; rlon:units = "m" ; double time(time) ; time:axis = "T" ; time:standard_name = "time" ; time:calendar = "gregorian" ; time:delta_t = "0000-00-00 (01:00:00)" ; time:units = "seconds since 1970-01-01 00:00:00" ; time:dt_sec = 3600 ;

PUM for product ARCTIC_ANALYSIS_FORECAST_WAV Ref: CMEMS-ARC-PUM- WAVE_002_010 Date : 8 Feb. 2018 Issue : 1.2 © EU Copernicus Marine Service – Public Page 20/ 20 // global attributes: :title = "ARCTIC_ANALYSIS_FORECAST_WAVE_002_006" ; :institution = "Norwegian Meteorological Institute" ; :source = "WAM wave model modified version cycle 4.5.4" ; :comment = "Original grid rotated" ; :history = "Wed Feb 7 10:14:24 2018: ncks -A -v forecast_reference_time W8km_force.nc MyWave_wam8_WAVE06.nc\nSat Feb 13 17:23:37 2016: ncatted -a ,global,d,, TRUEcoordDepthA8.nc" ; :NCO = "4.0.8" ; :Conventions = "CF-1.6" ;

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