PRODUCT USER MANUAL€¦ · II.4 Product System Description Domain Resolution and grid NORTH WEST...

PRODUCT USER MANUAL

For NWS Ocean Physical Analysis and

Forecast Product

NORTHWESTSHELF_ANALYSIS_FORECAST_PHY_004_013

Issue: 1.2

Contributors: M. Tonani, P. Sykes

Approval Date: JUNE 2020

NORTHWESTSHELF_ANALYSIS_FORECAST_PHY_004_013 03/04/2020

Issue: 1.2

© EU Copernicus Marine Service – Public Ref: CMEMS-NWS-PUM-004-013 sur 17

Issue Date § Description of Change Author Validated By

1.0 12/09/2018

All initial version M. Tonani, P. Sykes M. Tonani

1.1 18/01/2019

I, II.1, II.4, II.5.1,,

Target delivery time modified (13:00 instead of 12:00); corrected information for depth levels of TMB datasets and specification on product extension at the east boundary.

M. Tonani M. Tonani


Issue: 1.2


TABLE OF CONTENTS

GLOSSARY AND ABBREVIATIONS .............................................................................................................................. 4

I INTRODUCTION................................................................................................................................................. 5

I.1 Summary......................................................................................................................................................... 5

I.2 History of changes .......................................................................................................................................... 5

II Product DESCRIPTION: NORTHWESTSHELF_ANALYSIS_FORECAST_PHY_004_013 ........................................ 6

II.1 General Information about products ............................................................................................................. 6

II.2 Details of the datasets .................................................................................................................................... 7

II.3 Details on some parameters .......................................................................................................................... 8

II.4 Product System Description ........................................................................................................................... 8

II.5 Processing information ................................................................................................................................. 10

II.5.1 Update Time ....................................................................................................................................... 10

II.5.2 Time coverage .................................................................................................................................... 11

II.5.3 Time averaging .................................................................................................................................. 11

III HOW TO DOWNLOAD A PRODUCT ................................................................................................................ 12

III.1 Download a product through the CMEMS Web Portal Subsetter Service ................................................. 12

III.2 Download a product through the CMEMS Web Portal Ftp Service ........................................................... 12

III.3 Download a product through the CMEMS Web Portal Direct Get File Service ......................................... 12

IV FILES NOMENCLATURE and FORMAT ............................................................................................................ 13

IV.1 Nomenclature of files when downloaded through the Subsetter Service ................................................ 13

IV.2 Nomenclature of files when downloaded via CMEMS FTP Services ................................................. 13

IV.3 File Format: format name ........................................................................................................................... 14

IV.4 File size ......................................................................................................................................................... 14

IV.5 Remember: scale_factor & add_offset / missing_value / land mask ....................................................... 15

IV.6 Reading Software ........................................................................................................................................ 15

IV.7 Structure and semantic of netCDF maps files ........................................................................................ 16


Issue: 1.2


GLOSSARY AND ABBREVIATIONS

MFC Monitoring and Forecasting Centre

NWS North-West Shelf

NetCDF Network Common Data Form

CF Climate Forecast (convention for NetCDF)

SSS Sea surface salinity.

SSC Sea surface currents

SSH Sea surface height

RMS Root mean square

PC Production Centre

PU Production Unit

Meridional Velocity West to East component of the horizontal velocity vector

Zonal Velocity South to North component of the horizontal velocity vector

TMB Top, Middle, Bottom. Refers to terrain following water column levels for certain fields

ftp Protocol to download files

OpenDAP Open-Source Project for a Network Data Access Protocol. Protocol to download subset of data from a n-dimensional gridded dataset (ie: 4 dimensions: lon,lat,depth,time)

Subsetter CMEMS service tool to download a NetCDF file of a selected geographical box using values of longitude and latitude, and time range

DirectGetFile - DGF CMEMS service tool (FTP like) to download a NetCDF file


Issue: 1.2


I INTRODUCTION

I.1 Summary

This document is the user manual for the CMEMS north west shelf analysis and forecast product NORTHWESTSHELF_ANALYSIS_FORECAST_PHY_004_013. It provides aggregated analyses updated daily with 5-day forecast. An archive of analysis since 1st March 2016 up to real-time is available on the CMEMS server.

This product is updated as follows every day:

- the time series (analysis from the previous 2 days and 6 days forecast) is updated at the end of the operational production process

- old obsolete forecasts are deleted from the server

The product is published on the CMEMS dissemination server after automatic and human quality controls. Product is available on-line and disseminated through the CMEMS Information System. Files downloaded are in NetCDF format and follow CF-1.6 convention.

The analysis and forecasting system is described in the Quality Information Document (QUID): http://marine.copernicus.eu/documents/QUID/CMEMS-NWS-QUID-004-013.pdf.

More detailed information can be obtained from the CMEMS Service Desk ([email protected] ).

I.2 History of changes

Date Description of changes and impacted product

July 2020 Removal of TMB datasets.

Correction of 30 min shift in time_record of hourly dataset.

http://marine.copernicus.eu/documents/QUID/CMEMS-NWS-QUID-004-013.pdf

mailto:[email protected]


Issue: 1.2


II PRODUCT DESCRIPTION: NORTHWESTSHELF_ANALYSIS_FORECAST_PHY_004_013

II.1 General Information about products

Product name NORTHWESTSHELF_ANALYSIS_FORECAST_PHY_004_013

Geographical coverage 16°W 13°E ; 46°N 63°N

(The grid points from 10°E to 13°E are masked)

Variables Potential temperature

Salinity

Sea surface height

Horizontal velocity (eastward and northward components)

Bottom temperature

Mixed layer depth

Analysis Forecast

Update frequency daily daily

Available time series Two years before present 6-days forecast

Target delivery time Daily at 13pm (noon) UTC Daily at 13pm (noon) UTC

Temporal resolution Daily mean

Hourly Instantaneous

Daily mean

Hourly Instantaneous

Delivery mechanisms Subsetter DGF FTP

Horizontal resolution 1/33° longitude x 1/74° latitude

1.9± 0.4 km longitude x 1.5km latitude

Number of vertical levels 33 levels [surface, 3, 5, 10, 15, 20, 25, 30, 40, 50, 60, 75, 100, 125, 150, 175, 200, 225, 250, 300, 350, 400, 450, 500, 550, 600, 750, 1000, 1500, 2000, 3000, 4000, 5000]

Format NetCDF-4 (CF1.6)


Issue: 1.2


II.2 Details of the datasets

NORTHWESTSHELF_ANALYSIS_FORECAST_PHY_004_013

Hourly Instantaneous (hi) and Daily means (dm) fields of:

Potential temperature, salinity, zonal and meridional velocity (3D);

Sea Surface Height (SSH), sea bottom temperature, and Mixed layer depth (2D)

DATASETS Variables name in the NetCDF file and Unit

Long_name

CF Standard_name

MetO-NWS-PHY-hi-CUR

MetO-NWS-PHY-dm-CUR

vo [ms-1]

Northward Current Velocity in the Water Column

northward_sea_water_velocity

uo [ms-1]

Eastward Current Velocity in the Water Column

eastward_sea_water_velocity

MetO-NWS-PHY-hi-TEM

MetO-NWS-PHY-dm-TEM

thetao [degrees_C]

Sea Water Potential Temperature

sea_water_potential_temperature

MetO-NWS-PHY-hi-SAL

MetO-NWS-PHY-mm-SAL

so [1e-3]

Sea Water Salinity

sea_water_salinity

MetO-NWS-PHY-dm-BED bottomT [degrees_C]

Sea floor potential temperature

sea_water_potential_temperature_at_sea_floor

MetO-NWS-PHY-dm-MLD mlotst[m]

Ocean mixed layer thickness defined by density

ocean_mixed_layer_thickness_defined_by_sigma_theta

MetO-NWS-PHY-hi-SSH zos[m]

Sea surface height above geoid

sea_surface_height_above_geoid

MetO-NWS-PHY-001-013-STATIC Mask Land-sea mask sea_binary_mask

depth [m] depth depth

deptho [m] Bathymetry sea_floor_depth_below_geoid


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The model bathymetry is the same for the products NORTHWESTSHELF_ANALYSIS_FORECAST_WAV_004_014 and NWSHELF_ANALYSIS_FORECAST_PHY_004_015. It is distributed via FTP as NORTHWESTSHELF_ANALYSIS_FORECAST_PHY_004_013/ MetO-NWS-PHY-001-013-STATIC/ NWS-MFC_004_013_mask_bathy.nc.

II.3 Details on some parameters

mlotst [m] ocean_mixed_layer_thickness_defined_by_sigma_theta. It is the depth where the density increase compared to density at 3m depth corresponds to a temperature decrease of 0.2°C in local surface conditions.

zos [m]

sea_surface_height_above_geoid. The geoid is a surface of constant geopotential with which mean sea level would coincide if the ocean were at rest. The parameter “zos” is the difference between the actual sea surface height at any given time and place, and that which it would have if the ocean were at rest.

II.4 Product System Description

Domain

Resolution and grid

NORTH WEST EUROPEAN SHELF (16°W - 13°E ; 46°N - 63°N)

1/33° longitude x 1/74° latitude (958 x 1240 grid points)

1.9± 0.4 km longitude x 1.5km latitude

The longitude grid resolution varies with latitude. It is coarser at lower latitude (lat=46°N ->1,3 km), and finer at higher latitude (lat=63°N ->1.5km). The latitudinal grid resolution is constant in the whole model domain and is 1.5km).

The grid points from 10°E to 13°E are masked.

The AMM15 model is a nested regional ocean model configuration, defined on an identical grid to other NWS MFC modelling systems for waves.

It should be noted that whilst the North-West Shelf physic product is provided on a regular grid resolved at approximately 1.5 km, this is derived from a model with a native grid using a resolution of 1/60°. An Euler rotation is applied to the spherical‐polar grid such that a pseudo equator passes through the domain, resulting in a grid with a regular resolution of approximately 1.8 km both zonally and meridionally (Guihou


Issue: 1.2


Geographic coverage

et al. 2017).

A minimum depth of 10m is imposed in the ocean model for considering the sea level tidal excursion. Products below the surface in areas where the bathymetry is less than 10m could have be affected by this modelling choice.

The products are covering the area highlighted by the yellow dashed line.

NWS bathymetry (m) showing in yellow the domain of the AMM15 products and in red the domain of the AMM7 product, NORTHWESTSHELF_ANALYSIS_FORECAST_004_001).

The domain extends beyond the continental shelf in order to place the model's boundary region in the deep waters of the adjacent North-East Atlantic, but the focus region for the model comprises open waters of the shelf seas, i.e. (using UK terminology) the North Sea, Irish Sea, English Channel, Celtic Sea and Bay of Biscay.

Vertical grid The products are interpolated for users’ convenience, into 33 standard geopotential levels: [surface, 3, 5, 10, 15, 20, 25, 30, 40, 50, 60, 75, 100, 125, 150, 175, 200, 225, 250, 300, 350, 400, 450, 500, 550, 600, 750, 1000, 1500, 2000, 3000, 4000, 5000 m ].

The models native vertical grid has Hybrid S-σ-z-coordinates. The terrain-following coordinates system uses a stretching function to maintain near uniform vertical resolution at the surface. The number of S-σ-z levels is 51.

Model Version NEMO 3.6


Issue: 1.2


Tides Tidal forcing is included both on the open boundary conditions via a Flather radiation boundary conditions (Flather, 1976) and through the inclusion of equilibrium tide. The Topex Poseidon cross-over solution (Egbert and Erofeeva, 2002; TPX07.2, Atlantic Ocean 2011-ATLAS) provides 11 constituents for amplitude and phase of surface height and velocity at 1/12° (Tonani et al. 2019).

11 tidal constituent: M2, S2, N2, K2, K1, O1, P1, Q1, M4, MS4, MN4.

Atmospheric forcing ECMWF NWP

Assimilation scheme 3D Var FGAT. NEMOVAR.

Assimilated observations

In situ and satellite (L2/L3 products) SST

+ satellite SLA from CMEMS SL-TAC

+ temperature and salinity subsurface profiles from GTS and CMEMS INS-TAC

Boundaries conditions Atlantic lateral boundary: UK Met Office North Atlantic 1/12

Baltic lateral boundary: BALTICSEA_ANALYSYS_FORECAST_PHY_003_005

River discharge: daily climatology of gauge data averaged for 1980–2014. UK data were processed from raw data provided by the Environment Agency, the Scottish Environment Protection Agency, the Rivers Agency (Northern Ireland), and the National River Flow Archive (personal communication by Sonja M. van Leeuwen, CEFAS, 2016). For major rivers that were missing from this data set (e.g. along the French and Norwegian coast), data have been provided by the same climatology used by AMM7 (Vörösmarty et al., 2000 and Young and Holt, 2007).

Initial conditions The model run started 0n 10/01/2016 from initial condition from a long simulation.

Bathymetry EMODnet 2015

II.5 Processing information

II.5.1 Update Time

The products are updated daily at 13:00 UTC.


Issue: 1.2


Each day the (T-48h,T-24h] and (T-24h,T+00h] analyses are provided along with a 6 days forecast for all

products (with the first day of the forecast being for the day of production). An archive of the (T48h,T-

24h] Best Estimate analyses will be retained indefinitely (as described in Table above).

II.5.2 Time coverage

Analyses for the last two years + 6-day forecast.

II.5.3 Time averaging

Hourly instantaneous and daily mean values are available.

Hourly instantaneous values, [01:00; 02:00; 03:00; 04:00; 05:00; 06:00; 07:00; 08:00; 09:00; 10:00; 11:00; 12:00; 13:00; 14:00; 15:00; 16:00; 16:00; 17:00; 18:00; 19:00; 20:00; 21:00; 22:00; 23:00; 24:00],-are the output from the model at the model time step closest to the hour in UTC. There is no temporal averaging or interpolation performed.

Daily mean values are calculated as means of 25 hours, starting at midnight (UTC) and finishing on the following midnight to remove both diurnal and tidal cycles.


Issue: 1.2


III HOW TO DOWNLOAD A PRODUCT

III.1 Download a product through the CMEMS Web Portal Subsetter Service

You first need to register. Please find below the registration steps: http://marine.copernicus.eu/web/34-products-and-services-faq.php#1

Once registered, the CMEMS FAQ http://marine.copernicus.eu/web/34-products-and-services-faq.php will guide you on how to download a product through the CMEMS Web Portal Subsetter Service.

III.2 Download a product through the CMEMS Web Portal Ftp Service


Once registered, the CMEMS FAQ http://marine.copernicus.eu/web/34-products-and-services-faq.php will guide you on how to download a product through the CMEMS Web Portal FTP Service.

III.3 Download a product through the CMEMS Web Portal Direct Get File Service


Once registered, the CMEMS FAQ http://marine.copernicus.eu/web/34-products-and-services-faq.php will guide you on how to download a product through the CMEMS Web Portal Direct Get File Service.

http://marine.copernicus.eu/web/34-products-and-services-faq.php







Issue: 1.2


IV FILES NOMENCLATURE AND FORMAT

IV.1 Nomenclature of files when downloaded through the Subsetter Service

The NORTHWESTSHELF_ANALYSIS_FORECAST_PHY_004_013 files nomenclature when downloaded through the CMEMS Web Portal Subsetter is based on product dataset name and a numerical reference related to the request date on the MIS.

The scheme is: datasetname-nnnnnnnnnnnnn.nc

where :

- datasetname: as described in table 2

- nnnnnnnnnnnnn: 13 digit integer corresponding to the current time (download time) in milliseconds since January 1, 1970 midnight UTC.

- .nc: standard NetCDF filename extension.

Example:

MetO-NWS-PHYS-dm-CUR -1303461772348.nc

IV.2 Nomenclature of files when downloaded via CMEMS FTP Services

The below describes the near-real time forecast products:

- NORTHWESTSHELF_ANALYSIS_FORECAST_PHY_004_013

The files are delivered containing data for:

* the full spatial coverage of the model domain

* one variable or variable group

* a single day data

E.g.: each file contains a single daily mean or multiple higher-frequency values. The filenames contain fields that identify the model, domain, variable and time of the contents:

metoffice_foam1_amm15_NWS_XXXX_b20180825_dm20180827.nc

* metoffice: production centre that produced the file

* foam1: model system and version

* amm15: model configuration

* NWS: region

* XXXX: variable or variable group, see table 4 below

* b20180825: bulletin (production) date YYYYMMDD

* dm20180827: dm = daily mean or hi = hourly instantaneous, then data validity date YYYYMMDD


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TEM Potential temperature (including SST)

SAL Salinity

CUR Water velocities

SSH Sea surface height

MLD Mixed layer depth

BED Temperature at the sea floor

Table 4: Variable naming convention for the filenames

IV.3 File Format: format name

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 for more information, and to retrieve NetCDF software package.

NetCDF data 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.

IV.4 File size

DATASET NAME NAME OF FILE DIMENSION [MB]

MetO-NWS-PHY-dm-BED metoffice_foam1_amm15_NWS_BED_b{{yyyymmdd}}_dm{{yyyymmdd}}.nc

0.9


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MetO-NWS-PHY-dm-CUR metoffice_foam1_amm15_NWS_CUR_b{{yyyymmdd}}_dm{{yyyymmdd}}.nc

30

MetO-NWS-PHY-dm-MLD metoffice_foam1_amm15_NWS_MLD_b{{yyyymmdd}}_dm{{yyyymmdd}}.nc

0.8

MetO-NWS-PHY-dm-SAL metoffice_foam1_amm15_NWS_SAL_b{{yyyymmdd}}_dm{{yyyymmdd}}.nc

14

MetO-NWS-PHY-dm-TEM metoffice_foam1_amm15_NWS_TEM_b{{yyyymmdd}}_dm{{yyyymmdd}}.nc

17

MetO-NWS-PHY-hi-CUR metoffice_foam1_amm15_NWS_CUR_b{{yyyymmdd}}_hi{{yyyymmdd}}.nc

752

MetO-NWS-PHY-hi-SAL metoffice_foam1_amm15_NWS_SAL_b{{yyyymmdd}}_hi{{yyyymmdd}}.nc

342

MetO-NWS-PHY-hi-SSH metoffice_foam1_amm15_NWS_SSH_b{{yyyymmdd}}_hi{{yyyymmdd}}.nc

14

MetO-NWS-PHY-hi-TEM metoffice_foam1_amm15_NWS_TEM_b{{yyyymmdd}}_hi{{yyyymmdd}}.nc

420

IV.5 Remember: scale_factor & add_offset / missing_value / land mask

Real_Value = (Display_Value X scale_factor) + add_offset

The missing value for this product is: -32767s

Land and sea-ice masks are equal to “_FillValue” (see variable attribute on NetCDF file).

IV.6 Reading Software

NetCDF data can be browsed and used through a number of software, like:

ncBrowse: http://www.epic.noaa.gov/java/ncBrowse/, NetCDF Operator (NCO): http://nco.sourceforge.net/

PANOPLY (NASA): https://www.giss.nasa.gov/tools/panoply/

IDL, Matlab, GMT…

Useful information on UNIDATA: http://www.unidata.ucar.edu/software/netcdf/

http://www.epic.noaa.gov/java/ncBrowse/

http://nco.sourceforge.net/

https://www.giss.nasa.gov/tools/panoply/

http://www.unidata.ucar.edu/software/netcdf/


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IV.7 Structure and semantic of netCDF maps files

etcdf metoffice_foam1_amm15_NWS_SAL_b20200403_dm20200408 {

dimensions:

time = UNLIMITED ; // (1 currently)

depth = 33 ;

lat = 1240 ;

lon = 958 ;

variables:

short so(time, depth, lat, lon) ;

so:_FillValue = -32768s ;

so:long_name = "Sea Water Salinity" ;

so:standard_name = "sea_water_salinity" ;

so:scale_factor = 0.001 ;

so:units = "1e-3" ;

so:missing_value = -32768s ;

so:valid_max = 30000s ;

so:valid_min = -30000s ;

so:add_offset = 30. ;

double time(time) ;

time:units = "seconds since 2020-04-01 00:00:00" ;

time:long_name = "Validity time" ;

time:standard_name = "time" ;

time:calendar = "Gregorian" ;

time:axis = "T" ;

float lat(lat) ;

lat:nav_model = "grid_T" ;

lat:long_name = "latitude" ;

lat:standard_name = "latitude" ;

lat:cell_methods = "longitude: mean" ;

lat:units = "degrees_north" ;

lat:axis = "Y" ;

float lon(lon) ;


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lon:nav_model = "grid_T" ;

lon:long_name = "longitude" ;

lon:standard_name = "longitude" ;

lon:cell_methods = "latitude: mean" ;

lon:units = "degrees_east" ;

lon:axis = "X" ;

float depth(depth) ;

depth:units = "m" ;

depth:positive = "down" ;

depth:standard_name = "depth" ;

depth:long_name = "depth" ;

depth:axis = "Z" ;

// global attributes:

:grid_resolution = "Lat-lon 1.5 km" ;

:stop_time = "23:59Z" ;

:title = "daily-mean salinity (3D)" ;

:model_version = "AMM15v2" ;

:file_quality_index = "0s" ;

:start_time = "00:00Z" ;

:product_version = "1.0" ;

:Conventions = "CF-1.0" ;

:source = "UK Met Office Operational Suite, Atlantic Margin Model FOAM 1.5 km (tidal) run 2020-04-03" ;

:contact = "[email protected]" ;

:netcdf-version-id = "netCDF-4" ;

:start_date = "2020-04-08" ;

:stop_date = "2020-04-08" ;

:references = "http://marine.copernicus.eu/" ;

:creation_date = "2020-04-03 00:00Z" ;

:institution = "UK Met Office" ;

:history = "See source and creation_date attributes" ;

}

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