For Atlantic -Iberian Biscay Irish- Ocean Physics ......Atlantic -Iberian Biscay Irish- area (generated and provided by the CMEMS IBI-MFC). This document comprises a description of

PRODUCT USER MANUAL

For Atlantic -Iberian Biscay Irish- Ocean Physics Reanalysis Product

IBI_MULTIYEAR_PHY_005_002

Issue: 4.0

Contributors: Arancha Amo Baladrón, Bruno Levier, Marcos García Sotillo

Approval Date: SEPTEMBER 2020

PUM for Atlantic -Iberian Biscay Irish- Ocean Physic Reanalysis Product:


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© EU Copernicus Marine Service – Public Ref: CMEMS-IBI-PUM-005-002 Page 2/37

RECORD TABLE

Issue Date § Description of Change Author Validated By

1.0

05/05/2014

all

Creation of the document. Marcos G. Sotillo Arancha Amo Sylvain Cailleau

Enrique Álvarez Fanjul L. Crosnier

1.1 01/05/2015 all Change format to fit CMEMS graphical rules

L. Crosnier

2.0 15/12/2015 all Change due to CMEMS V2 Marcos G. Sotillo Arancha Amo Bruno Levier

3.0 15/12/2017 all Change related to the new reanalysis run (delivered for CMEMS V4)

Marcos G. Sotillo Arancha Amo Bruno Levier

3.1 15/01/2019 Change related to the temporal extension of the reanalysis IBI-MFC products.


Marcos G. Sotillo

3.2 08/04/2019 Change related to the temporal extension of the reanalysis IBI-MFC products. New dataset for static files.


Marcos G. Sotillo

3.3 03/04/2020 Change related to the temporal extension of the reanalysis IBI-MFC products. New Interim temporal extension.

Marcos G. Sotillo Arancha Amo Bruno Levier Roland Aznar

Marcos G. Sotillo

4.0 10/09/2020 New reanalysis IBI-MFC product (update of the whole catalogue). Modification of product/datasets names following new convention.

Marcos G. Sotillo Arancha Amo Bruno Levier Roland Aznar

Marcos G. Sotillo



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CONTENT

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

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

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

I.2 History of changes .......................................................................................................................................... 6

II Product DESCRIPTION: IBI_MULTIYEAR_PHY_005_002 .................................................................................. 7

II.1 General Information about products ............................................................................................................. 7

II.2 Details of the datasets .................................................................................................................................... 8

II.3 Product System Description ......................................................................................................................... 11

Numerical Ocean Code ................................................................................................................................. 12

II.4 Processing information ................................................................................................................................. 17

II.4.1 Update Time ....................................................................................................................................... 17

II.4.2 Time coverage .................................................................................................................................... 17

II.4.3 Time averaging .................................................................................................................................. 18

III HOW TO DOWNLOAD A PRODUCT ................................................................................................................ 19

III.1 Download a product through the CMEMS Web Portal Subsetter Service ................................................. 19

III.2 Download a product through the CMEMS Web Portal Ftp Service ........................................................... 19

III.3 Download a product through the CMEMS Web Portal Direct Get File Service ......................................... 19

IV FILES NOMENCLATURE and FORMAT ............................................................................................................ 20

IV.1 Nomenclature of files when downloaded through the Subsetter Service ................................................ 20

IV.2 Nomenclature of files when downloaded through the DGF and CMEMS FTP Services. ................ 20

IV.3 File Format: format name ........................................................................................................................... 22

IV.4 File size ......................................................................................................................................................... 22

IV.5 Remember: scale_factor & add_offset / missing_value / land mask ....................................................... 23

IV.6 Reading Software ........................................................................................................................................ 23

IV.7 Structure and semantic of netCDF maps files............................................................................................. 24

V REFERENCES .................................................................................................................................................... 36



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GLOSSARY AND ABBREVIATIONS

AVHRR Advanced Very High Resolution Radiometer – Optical instrument onboard NOAA satellites

CF Climate Forecast (convention for NetCDF)

CMEMS Copernicus Marine Environment Monitoring Service

DGF Direct Get File (FTP-like CMEMS service tool to download a NetCDF file)

ECMWF European Centre for Medium Range Weather forecast

FTP Protocol to download files

GLO Global

NetCDF Network Common Data Form

PUM Product User Manual

QUID Quality Information Document

Subsetter CMEMS service tool to download a NetCDF file of a selected geographical box and time range



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I INTRODUCTION

I.1 Summary

This document is the user manual for the ocean physic Multi-Year (MY) product IBI_MULTIYEAR_PHY_005_002, starting in 01/01/1993 and regularly updated (see product improvements pages http://marine.copernicus.eu/services-portfolio/product-improvements), in the Atlantic -Iberian Biscay Irish- area (generated and provided by the CMEMS IBI-MFC). This document comprises a description of data files and user interfaces to get access to this product, as well as a brief description of the reanalysis system used in its generation.

The IBI MFC MY ocean physic product consists of 3D daily and monthly mean fields of the following variables: Temperature, Salinity, Sea Surface Height, Zonal and Meridional Velocity components, Mix Layer Depth and Sea Bottom Temperature. Hourly means of surface fields such as Sea Surface Height, Surface Temperature and Currents, together with Barotropic Velocities are also provided. This product is defined on a standard grid at 1/12 degree.

The product is organised in 4 datasets:

- cmems_mod_ibi_phy_my_0.083deg-2D_PT1H-m: containing hourly averaged values of the variables.

- cmems_mod_ibi_phy_my_0.083deg-3D_P1D-m: containing daily averaged values of the variables.

- cmems_mod_ibi_phy_my_0.083deg-3D_P1M-m: containing monthly averaged values of the variables.

- cmems_mod_ibi_phy_my_0.083deg-3D_static: containing the static fields for the system (mask and bathymetry).

The product is available on-line and disseminated through the CMEMS Dissemination Unit. Files downloaded are in netCDF-4 format and follow CF-1.0 convention.

The reanalysis system is described in the Quality Information Document (QUID): http://marine.copernicus.eu/documents/QUID/CMEMS-IBI-QUID-005-002.pdf

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

http://marine.copernicus.eu/services-portfolio/product-improvementshttp://marine.copernicus.eu/documents/QUID/CMEMS-IBI-QUID-005-002.pdfmailto:[email protected]



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I.2 History of changes

System Version

(Project/Service)

Operational launch

Novelties

IBI-V2 (MyOcean2)

FIRST RELEASE

19/04/2016 First release of the IBI-MFC PHY-V2 MY hindcast. The IBI physical Product, delivered to users from CMEMS V3 release (temporal coverage 2002-2014).

IBI-V4 (CMEMS-I)

FIRST RELEASE

26/04/2018 First release of the IBI-MFC MY PHY/BGC-V4 product.

Delivered to users from CMEMS V4 release, with a temporal coverage from 01/01/1992 to 31/12/2016.

Both physical and biogeochemical models updated (NEMO/PISCES V3.6). Data Assimilation system released and new observational data sources included.

CMEMS Apr 2019 release

(CMEMS-II)

TEMPORAL EXTENSION

16/04/2019 Extension of the IBI-MFC MY PHY/BGC-V4 product to cover the period 01/01/1992 to 24/12/2017. In addition to the year 2017, the years 2014 to 2016 were run again to take into account new reprocessed observational and forcing data.

CMEMS Jul 2019 release (CMEMS-II) TEMPORAL EXTENSION

09/07/2019 Extension of the IBI-MFC MY PHY/BGC-V4 product to cover the period 01/01/1992 to 24/12/2018. In addition to the year 2018, the years 2014 to 2017 were re-run. New dataset for static files.

CMEMS Jul 2020 release (CMEMS-II) TEMPORAL EXTENSION

07/07/2020 Extension of the IBI-MFC MY PHY/BGC-V4 product to cover the period 01/01/1992 to 24/12/2019. In addition to the year 2019, the year 2018 was re-run.

CMEMS Dec 2020 release (CMEMS-II)

FIRST RELEASE

15/12/2020

First release of the IBI-MFC MY PHY/BGC-V5 product Update of the whole historic catalogue to cover the period 01/01/1993 to 24/12/2019 Renaming of product/datasets. New Interim temporal extensions.

Table 1: Historical evolution of the IBI MFC Multi-Year Physical Reanalysis System along the Service. Time coverage of each model set-up used to produce the IBI_MULTIYEAR_PHY_005_002 product, as well as main novelties introduced, are provided.



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II PRODUCT DESCRIPTION: IBI_MULTIYEAR_PHY_005_002

The IBI_MULTIYEAR_PHY_005_002 product provides 3D daily and monthly ocean fields as well as hourly mean values for some surface variables for the IBI area. The time coverage starts in 01/01/1993. Daily and monthly averages of 3D Temperature, Salinity, Mix Layer Depth, Sea Bottom Temperature, Zonal and Meridional Velocity components and Sea Surface Height are provided. Hourly means of surface fields for variables such as Sea Surface Height, Mix Layer Depth, Surface Temperature and Currents, together with Barotropic Velocities are also provided. Output files are delivered in NetCDF-4 format (using CF/COARDS 1.0 convention).

II.1 General Information about products

Product name IBI_MULTIYEAR_PHY_005_002

Geographical coverage IBI longitude: [-19, 5] deg latitude: [26, 56] deg

Variables cmems_mod_ibi_phy_my_0.083deg-2D_PT1H-m Temperature Eastward velocity Northward velocity Zonal barotropic velocity Meridional barotropic velocity Sea surface height Ocean mixed layer thickness defined by density cmems_mod_ibi_phy_my_0.083deg-3D_P1D-m Sea floor potential temperature Salinity Temperature Eastward velocity Northward velocity Sea surface height Ocean mixed layer thickness defined by density cmems_mod_ibi_phy_my_0.083deg-3D_P1M-m Sea floor potential temperature Salinity Temperature Eastward velocity Northward velocity Sea surface height Ocean mixed layer thickness defined by density



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cmems_mod_ibi_phy_my_0.083deg-3D_static Bathymetry Mask Coordinates (e1t, e2t,e3t) mdt

Multi-Year/

Update Frequency

Reanalysis

Monthly Interim extensions.

Biannually reprocessed temporal extensions.

Assimilated observations: - Altimeter data (along-track Sea Level Anomalies) - In situ temperature and salinity vertical profiles (CORA 5.2 database). - Satellite sea surface temperature (OSTIA).

Available time series From 1st January 1993 and regularly updated (see product improvements pages http://marine.copernicus.eu/services-portfolio/product-improvements/).

Target delivery time N/A

Temporal resolution Hourly, daily and monthly averaged values

Horizontal resolution 1/12° (equirectangular grid)

Number of vertical levels Hourly dataset: surface level.

Daily and monthly datasets: 50 vertical levels.

Format NetCDF-4 CF1.0

Delivery mechanisms Subsetter DGF FTP

Table 2: General Information about the IBI_MULTIYEAR_PHY_005_002 product.

II.2 Details of the datasets

The IBI_MULTIYEAR_PHY_005_002 product contains 4 different datasets:

- cmems_mod_ibi_phy_my_0.083deg-2D_PT1H-m

- cmems_mod_ibi_phy_my_0.083deg-3D_P1D-m

- cmems_mod_ibi_phy_my_0.083deg-3D_P1M-m

- cmems_mod_ibi_phy_my_0.083deg-3D_static

The first three datasets offer information for the whole IBI service domain and provide surface hourly averaged fields, 3D daily averaged fields, and 3D monthly averaged fields, respectively. These datasets

http://marine.copernicus.eu/services-portfolio/product-improvements/http://marine.copernicus.eu/services-portfolio/product-improvements/



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are composed of post-processed data into a regular lon/lat grid (analogous to the one used for the daily IBI forecast product IBI_ANALYSISFORECAST_PHY_005_001, but with a 1/12º horizontal resolution), that goes from 26.0N to 56.0N in latitude and 19.0W to 5.0E in longitude. Latitude and longitude step is 0.08333 deg. The resulting horizontal grid extends to 289x361 grid points. Information from all surface variables contained in this dataset is provided at same grid points.

3D datasets (daily and monthly) are provided at 50 vertical levels (z-type; a sub-sampling of the 75 native vertical levels) that goes from a surface level at 0.5 m to the deepest level at 5698 m. The resulting grid extends to 289 x 361 x 50 grid points. Data from all the variables contained in the dataset is provided at same grid points.


cmem

s_m

od_i

bi_p

hy_m

y_0.

083d

eg-3

D_P1

D-m

cmem

s_m

od_i

bi_p

hy_m

y_0.

083d

eg-3

D_P1

M-m

contains all the variables.

Temperature [ºC] thetao Temperature sea_water_potential_temperature Salinity [PSU] so Salinity sea_water_salinity Zonal Velocity [m/s] uo Eastward velocity eastward_sea_water_velocity Meridional Velocity [m/s] vo Northward velocity northward_sea_water_velocity Sea Surface Height [m] zos Sea surface height sea_surface_height_above_geoid Mix Layer Depth [m] mlotst Ocean mixed layer thickness defined by density ocean_mixed_layer_thickness_defined_by_sigma_theta



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Sea Bottom Temperature [ºC] Bottom Sea floor potential temperature sea_water_potential_temperature_at_sea_floor

cmem

s_m

od_i

bi_p

hy_m

y_0.

083d

eg-2

D_PT

1H-m

Temperature [ºC] thetao Temperature sea_water_potential_temperature Zonal Velocity [m/s] uo Eastward velocity eastward_sea_water_velocity Meridional Velocity [m/s] vo Northward velocity northward_sea_water_velocity Zonal Barotropic velocity [m/s] ubar zonal barotropic velocity barotropic_eastward_sea_water_velocity Meridional Barotropic velocity [m/s] vbar meridional barotropic velocity barotropic_northward_sea_water_velocity Sea Surface Height [m] zos Sea surface height sea_surface_height_above_geoid Mix Layer Depth [m] mlotst Ocean mixed layer thickness defined by density ocean_mixed_layer_thickness_defined_by_sigma_theta



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cmem

s_m

od_i

bi_p

hy_m

y_0.

083d

eg-3

D_st

atic

contains the mask, bathymetry, coordinates and mdt files

IBI-MFC_005_002_mask_bathy.nc deptho [m] Bathymetry sea_floor_depth_below_geoid mask_thetao [] Land-sea mask: 1 = sea ; 0 = land sea_binary_mask mask_uo [] Land-sea mask: 1 = sea ; 0 = land sea_binary_mask mask_vo [] Land-sea mask: 1 = sea ; 0 = land sea_binary_mask IBI-MFC_005_002_coordinates.nc e1t [m] Cell dimension along X axis e2t [m] Cell dimension along Y axis e3t [m] Cell dimension along Z axis IBI-MFC_005_002_mdt.nc mdt [m] Mean dynamic topography sea_surface_height_above_geoid

Table 3 IBI_MULTIYEAR_PHY_005_002 product: list of datasets (column 1), variables contained in each dataset with their corresponding units, long and standard names (column 2).

II.3 Product System Description

Short description

The IBI (Iberian Biscay Irish) Ocean Reanalysis system provides 3D monthly and daily ocean fields, as well as hourly mean values for some surface variables, since 01/01/1993. Monthly and daily averages of 3D Temperature, Salinity, Mix Layer Depth, Sea Bottom Temperature, Zonal and Meridional Velocity components and Sea Surface Height are provided. Hourly means of surface fields for variables such as Sea Surface Height, Mix Layer Depth, Surface Temperature and Currents, together with Barotropic



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Velocities are also provided. The IBI model numerical core is based on the NEMO v3.6 ocean general circulation model run at 1/12° horizontal resolution. Altimeter data, in situ temperature and salinity vertical profiles and satellite sea surface temperature are assimilated.

Detailed description

Numerical Ocean Code

The IBI model numerical core is based on the NEMO v3.6 ocean general circulation model (Madec, 2008). This model solves the three-dimensional finite-difference primitive equations in spherical coordinates discretized on an Arakawa-C grid. It assumes hydrostatic equilibrium and Boussinesq approximation.

The primitive equations are discretized on an horizontal curvilinear grid which is a refined subset at 1/12° (≈6–9 km) of the so-called “ORCA” tripolar grid, commonly used in other NEMO-based large-scale and global modelling experiments (Barnier et al., 2006). 75 z levels are used in the vertical, with a resolution decreasing from ∼1 m in the upper 10 m to more than 400 m in the deep ocean. A partial step representation of the very last bottom wet cell is used with some constraints on the resulting minimum bottom cell thickness to guarantee model stability (it must be greater than 15 m or 20 % of the reference grid thickness).

In order to properly simulate fast external gravity waves such as tidal motions, a non-linear split explicit free surface (Shchepetkin and McWilliams, 2004) is used. Because of the explicit simulations of tides, sea level elevation can become large on the shelf compared to the local depth. In practice, all model vertical thicknesses are remapped in the vertical at each time step to account for the varying fluid height

Vertical mixing is parameterized according to a k-ε model implemented in the generic form proposed by Umlauf and Burchard (2003) including surface wave breaking induced mixing. The background turbulent variables are set to their molecular values and are modified in function of the mixing induced by the internal tides not resolved by the model following the parametzrization of de Lavergne et al. (2016). Tracers advection is computed with the QUICKEST scheme developed by Leonard (1979) conjugated to the limiter of Zalezak (1979). This third-order scheme is well suited to the high resolution used here and the modelling of the sharp front characteristics of coastal environments. Lateral sub-grid-scale mixing is parameterized according to horizontal biharmonic operators for momentum (with a diffusion coefficient of -1.25e10 m4s-1). A vector invariant form of the momentum equations and the energy–enstrophy discretization of vorticity terms are used (Barnier et al., 2006).

The original bathymetry is derived from the 30 arc-second resolution GEBCO 08 dataset (Becker et al., 2009) merged with several local databases (F. Lyard, personal communication, 2010). At open boundaries, within 30-point-wide relaxation areas, bathymetry is exactly set to the parent grid model bathymetry and progressively merged with the interpolated dataset described above. This approach and the identical vertical grid as in the parent system imply that no vertical extrapolation of open boundary data is necessary.

The IBI run has been forced with hourly atmospheric fields (10-m wind, surface pressure, 2-m temperature, relative humidity, precipitations, short-wave and long-wave radiative fluxes) provided by ERA5. IFS empirical bulk formulae (ECMWF, 2014; Brodeau et al., 2017) are used to compute latent sensible heat fluxes, evaporation, and surface stress. Solar penetration is parameterized according to a



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five-bands exponential scheme (considering the UV radiations) function of surface chlorophyll concentrations using the CMEMS ESA-CCI product covering the North East Atlantic area including the IBI domain at the monthly frequency. The reprocessed product is referenced as OCEANCOLOUR_ATL_CHL_L4_REP_OBSERVATIONS_009_091 while the NRT product is referenced as OCEANCOLOUR_ATL_CHL_L4_NRT_OBSERVATIONS_009_090.

Lateral open boundary data (temperature, salinity, velocities and sea level) are interpolated from the daily outputs from the Global reanalysis at 1/4° of resolution (CMEMS product GLOBAL_REANALYSIS_PHY_001_025). These are complemented by 11 tidal harmonics (M2, S2, N2, K1, O1, Q1, M4, K2, P1, Mf, Mm) built from FES2004 (Lyard et al., 2006) and TPXO7.1 (Egbert and Erofeeva, 2002) tidal model solutions. Atmospheric pressure component, missing in the large-scale parent system sea level outputs, is added hypothesing pure isostatic response at open boundaries (inverse barometer approximation).

The simulation started at rest, with initial temperature, salinity, velocity components and sea surface height provided by the global reanalysis GLORYS2V4 (CMEMS product GLOBAL_REANALYSIS_PHY_001_025). The date of start is 1st January 1993.

Fresh water river discharge inputs are implemented as lateral open boundary condition for 33 rivers. Flow rate data based on daily observations (gathered in PREVIMER project for 9 rivers), simulated data (from SMHI E-HYPE hydrological model (http://e-hypeweb.smhi.se)) and climatology (using monthly climatological data taken from GRDC (http://www.bafg.de/GRDC) and French “Banque Hydro” dataset (http://www.hydro.eaufrance.fr/)) are used in best available basis. An extra coastal runoff rate climatology (in monthly basis) is used as IBI forcing to complement the high frequency forcing associated to the main 33 rivers. This added fresh water input make the IBI forcing consistent with the ones imposed in the global system (derived from the Dai and Trenberth climatology). More details of physical parameterizations can be found in Maraldi et al. (2013).

Data Assimilation

The data assimilation scheme relies on a reduced-order Kalman filter. It is based on the Singular Evolutive Extended Kalman Filter (SEEK) formulation introduced by Pham et al. (1998). This approach has been used for several years at Mercator Ocean. It has been implemented in different ocean model configurations with a 5-day assimilation window (e.g. Tranchant et al., 2008; Lellouche et al., 2013). In all Mercator Ocean forecasting systems, the forecast error covariance is based on the statistics of a collection of predefined 3-D ocean state anomalies. The anomalies are computed from a long numerical experiment (typically around 8 years) with respect to a running mean so that they can provide an estimate of the 7-day scale error on the ocean state at a given period of the year for Temperature (T), Salinity (S), zonal velocity (U), meridional velocity (V) and Sea-Surface-Height (SSH). More precisely, each temporal anomaly corresponds to the difference between the model state

and a running mean over a fixed time period window ranging from –τ to τ (Figure 1). It should also be noted that the analysis increment is a linear combination of these anomalies and depends on the innovation (observation minus model forecast equivalent as in Ide al., 1997) and on the specified observation errors. This approach is similar to the Ensemble Optimal Interpolation developed by Oke et al. (2008). The last feature of the model forecast covariance is a localization technique which sets the covariances to zero beyond a distance defined as twice the local spatial correlation scale. Spatial (zonal and meridional directions) and temporal correlation scales (Figure 2) are then used to define an “influence bubble” around the analysis point in which data are also

http://e-hypeweb.smhi.se/http://www.bafg.de/GRDC



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selected. For the IBI reanalysis, these ocean states come from a reference simulation (free simulation without assimilation from 1993 to 2018) carried out with the same ocean model configuration and same forcing. For each analysis cycle, we use 450 ocean state anomalies.

In practice, the SAM2 system is a sequential scheme. Here, we use a 5-day assimilation cycle. The observations minus model forecasts are calculated during the model integration at the right location and at the right time. After each analysis, the data assimilation produces increments of sea surface height (SSH), temperature, salinity and velocity. All these increments are applied progressively in the hindcast run using the Incremental Analysis Update (IAU) method (e.g. Bloom at al. 1996; Benkiran et al. 2008). It avoids inducing a shock in the model after each analysis, because of imbalance between the analysis increment and the model physics.

Figure 1: Schematic representation of the anomalies calculation along a model trajectory

Figure 1: Temporal (days), zonal and meridional (km) correlation scales used in this Mercator Ocean system

Assimilated observations

Altimeter data, in situ temperature and salinity vertical profiles and satellite sea surface temperature are assimilated to estimate the initial conditions for numerical ocean forecasting.



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Altimeter data consist of along-track Sea Level Anomalies (SLA) (CMEMS product SEALEVEL_GLO_PHY_L3_NRT_OBSERVATIONS_008_043 for near real time and SEALEVEL_GLO_PHY_L3_REP_OBSERVATIONS_008_061 for reprocessed). Observations along tracks are smoothed by several altimetric corrections (Le Traon et al., 2001). A Mean Dynamic Topography (MDT) is also used as a reference for SLA assimilation. This MDT is based on the “CNES-CLS13” MDT (Rio et al., 2014) with adjustments made using high resolution analyses, the last version of the GOCE geoid and an improved Post Glacial Rebound (also called Glacial Isostatic Adjustment).

Temperature and salinity in situ vertical profiles from the CORA 5.2 database tailored for assimilation (INSITU_GLO_TS_ASSIM_REP_OBSERVATIONS_013_051) and near real time in-situ observational data sources (INSITU_GLO_TS_ASSIM_NRT_OBSERVATIONS_013_047) are assimilated (CORA from 1992 to June 2019, NRT from June 2019).

OSTIA satellite SST is assimilated (SST_GLO_SST_L4_REP_OBSERVATIONS_010_011).

Observation operator

In data assimilation, the computation of innovation requires defining an observation operator to represent the model equivalent of the observation. In the present system, prognostic variables are interpolated on a quadrilateral grid, i.e., on the four grid points surrounding the observation. The four weights are calculated with a bi-linear remapping interpolation. In the real time Mercator Ocean systems, the model sea level is filtered from the high frequency barotropic signal in a close manner than what is done in the altimetric data processing (e.g. Carrère at al. 2003; Dibarboure et al., 2011).

Adaptive tuning of observation error and implementation

In order to refine the prescription of observation errors, adaptive tuning of observation errors for the SLA and SST has been implemented. The method has not been used for temperature and salinity vertical profiles because of the lack of in situ data. Then, 3D fixed observation errors are used for the assimilation of in situ temperature and salinity vertical profiles.

The adaptive tuning method consists in the computation of a ratio which is a function of observation errors, innovations and residuals. It helps correcting inconsistencies on the specified observation errors. Following Desroziers et al. (2005), this ratio can be expressed as:

Ideally, is equal to 1. When the ratio is less (respectively larger) than 1, it means that the observation error is overestimated (respectively underestimated). The objective of this diagnostic is to improve the error specification by tuning an adaptive weight coefficient acting on the error of each assimilated observation. As a first guess of the method, the initial prescribed observation error matches the one used in the previous system (Lellouche at al., 2013) where the observation error variance was increased near the coast and on the shelves for the assimilation of SLA, and increased only near the coast (within 50 km of the coast) for the assimilation of SST. We also use a map of minimum error for altimetry in order to prevent the method to decrease to much the error.

BIAS Correction



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In addition to the assimilation scheme, a method of bias correction has been developed. This method is based on a 3-D-Var approach which takes into account cumulative innovations over the last 3-month period in order to estimate large-scale temperature and salinity biases when enough observations are available. The aim of the bias correction is to correct the large-scale, slowly evolving error of the model, whereas the SAM assimilation scheme is used to correct the smaller scales of the model forecast error. For IBIRYS the correction is applied on a time-window of 90 days.

Domain

Resolution and grid

Geographic coverage

IBI (19°W-5°E; 26°S – 56°N)

1/12º; regular grid; 289 x 361

Data provided in a regular lon/lat grid that goes from 26.0N to 56.0N in latitude and 19.0W to 5.0E in longitude. Latitude and longitude step is

0.08333 deg. The resulting horizontal grid extends to 289x361 grid points.

Model version NEMO v3.6

Horizontal resolution 1/12°

Vertical coord. z*=f(ssh)

75 levels

Partial bottom cells

Bathymetry Composite (GEBCO_08 + different local databases)

Free surface Explicit, non-linear, time-splitting

Vertical mixing k-epsilon

Tracer advection QUICKEST + Zalezak

Atmospheric forcings Hourly ERA5 (10-m wind, surface pressure, 2-m temperature, relative humidity, precipitations, short-wave and long-wave radiative fluxes)



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Rivers As lateral point sources.

Merge of daily SMHI & PREVIMER & Monthly climatology (GRDC), 35 rivers.

2D flux in complement from derived from the Dai and Trenberth climatology.

Assimilation scheme SAM2 (SEEK Filter) + IAU + bias correction + adaptive error

Surge capability Yes

Tides Yes (11 tidal components, astro pot)

Ocean color effects OCEANCOLOUR_ATL_CHL_L4_REP_OBSERVATIONS_009_091

and

OCEANCOLOUR_ATL_CHL_L4_NRT_OBSERVATIONS_009_090

CMEMS products

- before 1998, monthly climatology 1998-2019

- from 1998, monthly values

IC & OBC GLORYS2V4 ¼°

Table 4: Summary of IBIRYS characteristics.

II.4 Processing information

II.4.1 Update Time

The IBI reanalysis product is a static product and therefore no update time is applicable.

II.4.2 Time coverage

An archive of reanalysis since 1st January 1993 regularly updated (see product improvements pages http://marine.copernicus.eu/services-portfolio/product-improvements/) is available on the CMEMS server.

Since CMEMS December 2020 release, the IBI PHY reanalysis is planned to be updated following a new catalogue policy (see Figure 3) destined to ensure the dissemination of a quasi-near real time reanalysis timeseries.

For this purpose, every month (M), interim MY products covering the previous month (M-1) are generated with the same model and configuration used for the current reanalysis. For producing M-1 outputs, the model is forced with ERA5T atmospheric data from the ECMWF and it assimilates near real time (NRT) upstream data, since reprocessed (REP) data for such a short term are non-available.

http://marine.copernicus.eu/services-portfolio/product-improvements/



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Then, at a biannual frequency, the model is rerun from M-18 to M-13 months in order to use REP upstream data and ERA5 ECMWF atmospheric forcing and to ensure that the best available MY products are generated.

Figure 3: Conceptual scheme for generation of the IBI PHY MY product catalogue. The historical time series of IBI PHY MY are monthly updated with Interim reanalysis of the previous month (M-1) assimilating near real time (NRT) upstream data, and biannually updated with final reanalysis of M-18 to M-13 months assimilating reprocessed (REP) upstream data.

II.4.3 Time averaging

As it was stated in the dataset description, information from the IBI reanalysis is provided on hourly, daily and monthly basis already post-processed into a regular lon/lat grid (analogous to the one used for the daily IBI forecast product (IBI_ANALYSISFORECAST_PHY_005_001), but with 1/12º horizontal resolution).



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



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IV FILES NOMENCLATURE AND FORMAT

The file naming of the downloaded files differs on the basis of the chosen download mechanism (i.e. FTP, Subsetter or DGF services). All the datasets can be downloaded through the three download mechanisms, except the cmems_mod_ibi_phy_my_0.083deg-3D_static dataset, only available through the FTP User Interface.

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

IBI_MULTIYEAR_PHY_005_002 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 previously

- 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:

cmems_mod_ibi_phy_my_0.083deg-2D_PT1H-m_1518187723177.nc

cmems_mod_ibi_phy_my_0.083deg-3D_P1D-m_1518187723180.nc

cmems_mod_ibi_phy_my_0.083deg-3D_P1M-m_1518187729340.nc

IV.2 Nomenclature of files when downloaded through the DGF and CMEMS FTP Services.

In case of download through the DGF interface, one obtains a zip file:

The scheme is: datasetname_nnnnnnnnnnnnn.zip

where:

- datasetname: as described previously

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

- .nc: standard NetCDF filename extension.

The zip file contains one NetCDF file for every day/month requested.

Once the zip file downloaded through the DGG interface is unzipped, files inside present the same nomenclature than the ones downloaded through the FTP service.



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Example:

Downloads corresponding to two days/months (19990101 and 19990102/199901 and 199902) of data from hourly, daily and monthly datasets:

cmems_mod_ibi_phy_my_0.083deg-2D_PT1H-m_1518187973405.zip

CMEMS_v5r1_IBI_PHY_MY_PdE_01hav_19990101_19990101_R20201201_RE01.nc


cmems_mod_ibi_phy_my_0.083deg-3D_P1D-m_1518188091707.zip

CMEMS_v5r1_IBI_PHY_MY_PdE_01dav_19990101_19990101_R20201201_RE01.nc


cmems_mod_ibi_phy_my_0.083deg-3D_P1M-m_1518188124497.zip

CMEMS_v5r1_IBI_PHY_MY_PdE_01mav_19990101_19990131_R20201201_RE01.nc


File nomenclature, when downloaded through the CMEMS Web Portal DGF (after unzip) or FTP service, is based on production date and field date.

CMEMS_{fileVersion}_{region}_PHY_MY_PdE_{freqFlag}_{validDate}_{valiDate}_R{bulletinDate}_{productType}.nc

Where:

- region: a three-letter code for the region, IBI in this case.

- fileVersion: vxry, where x, y are the version and release number, respectively

- freqFlag: the frequency of data values in the file (01hav = hourly averaged, 01dav = daily averaged, 01mav = monthly averaged).

- validate: YYYYMMDD is the valid date of the fields contained in the file. For the monthly dataset, this field is the initial and final date of the month.

- bulletinDate: RYYYYMMDD is the bulletin date, i.e.: data production date (e.g.: R20201201)

- productType: is a two-letter code for the product type, in this case, RE01 for reanalysis.

Examples:

From the hourly dataset request:


From the daily dataset request:


From the monthly dataset request:




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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 FILE NAME DIMENSION [MB]

NetDCF-4 with compression

cmems_mod_ibi_phy_my_0.083deg-2D_PT1H-m

CMEMS_v5r1_IBI_PHY_MY_PdE_01hav_${ validDate}_${validDate}_R${bulletinDate}_RE01.nc


14

cmems_mod_ibi_phy_my_0.083deg-3D_P1D-m

CMEMS_v5r1_IBI_PHY_MY_PdE_01dav_${ validDate}_${validDate}_R${bulletinDate}_RE01.nc


13



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cmems_mod_ibi_phy_my_0.083deg-3D_P1M-m

CMEMS_v5r1_IBI_PHY_MY_PdE_01mav_${ iniDate}_${endDate}_R${bulletinDate}_RE01.nc Where: iniDate: first day of the month endDate: last day of the month


12

cmems_mod_ibi_phy_my_0.083deg-3D_static

IBI-MFC_005_002_mask_bathy.nc

IBI-MFC_005_002_coordinates.nc

IBI-MFC_005_002_mdt.nc

16

45

1

Table 5: Name and size of files in each dataset (compressed -zip- and uncompressed values).

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

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).

Land values are treated as missing value.

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/

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



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IV.7 Structure and semantic of netCDF maps files

Examples of structure and header of IBI_MULTIYEAR_PHY_005_002 files downloaded through DGF or FTP User interfaces.

- cmems_mod_ibi_phy_my_0.083deg-2D_PT1H-m

netcdf CMEMS_v5r1_IBI_PHY_MY_PdE_01hav_20191201_20191201_R20201201_RE01 { dimensions: time = UNLIMITED ; // (24 currently) latitude = 361 ; longitude = 289 ; variables: float time(time) ; time:axis = "T" ; time:calendar = "gregorian" ; time:standard_name = "time" ; time:units = "hours since 1950-01-01 00:00:00" ; time:long_name = "time" ; time:_CoordinateAxisType = "Time" ; float longitude(longitude) ; longitude:standard_name = "longitude" ; longitude:long_name = "Longitude" ; longitude:units = "degrees_east" ; longitude:axis = "X" ; longitude:unit_long = "Degrees East" ; longitude:step = "0.08333f" ; longitude:_CoordinateAxisType = "Lon" ; float latitude(latitude) ; latitude:standard_name = "latitude" ; latitude:long_name = "Latitude" ; latitude:units = "degrees_north" ; latitude:axis = "Y" ; latitude:unit_long = "Degrees North" ; latitude:step = "0.08333f" ; latitude:_CoordinateAxisType = "Lat" ; short thetao(time, latitude, longitude) ; thetao:standard_name = "sea_water_potential_temperature" ; thetao:long_name = "Temperature" ; thetao:units = "degrees_C" ; thetao:add_offset = 10.f ; thetao:scale_factor = 0.001f ; thetao:_FillValue = -32767s ; thetao:unit_long = "degrees_C" ; thetao:valid_min = -12000s ; thetao:valid_max = 22000s ; short ubar(time, latitude, longitude) ; ubar:standard_name = "barotropic_eastward_sea_water_velocity" ;



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ubar:long_name = "zonal barotropic velocity" ; ubar:units = "m s-1" ; ubar:add_offset = 0.f ; ubar:scale_factor = 0.001f ; ubar:_FillValue = -32767s ; ubar:unit_long = "Meters per second" ; ubar:valid_min = -3000s ; ubar:valid_max = 3000s ; short uo(time, latitude, longitude) ; uo:standard_name = "eastward_sea_water_velocity" ; uo:long_name = "Eastward velocity" ; uo:units = "m s-1" ; uo:add_offset = 0.f ; uo:scale_factor = 0.001f ; uo:_FillValue = -32767s ; uo:unit_long = "Meters per second" ; uo:valid_min = -3000s ; uo:valid_max = 3000s ; short vbar(time, latitude, longitude) ; vbar:standard_name = "barotropic_northward_sea_water_velocity" ; vbar:long_name = "meridional barotropic velocity" ; vbar:units = "m s-1" ; vbar:add_offset = 0.f ; vbar:scale_factor = 0.001f ; vbar:_FillValue = -32767s ; vbar:unit_long = "Meters per second" ; vbar:valid_min = -3000s ; vbar:valid_max = 3000s ; short vo(time, latitude, longitude) ; vo:standard_name = "northward_sea_water_velocity" ; vo:long_name = "Northward velocity" ; vo:units = "m s-1" ; vo:add_offset = 0.f ; vo:scale_factor = 0.001f ; vo:_FillValue = -32767s ; vo:unit_long = "Meters per second" ; vo:valid_min = -3000s ; vo:valid_max = 3000s ; short zos(time, latitude, longitude) ; zos:standard_name = "sea_surface_height_above_geoid" ; zos:long_name = "Sea surface height" ; zos:units = "m" ; zos:add_offset = 0.f ; zos:scale_factor = 0.001f ; zos:_FillValue = -32767s ; zos:unit_long = "Meters" ; zos:valid_min = -10000s ; zos:valid_max = 10000s ;



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short mlotst(time, latitude, longitude) ; mlotst:_FillValue = -32767s ; mlotst:add_offset = 2000.f ; mlotst:long_name = "Ocean mixed layer thickness defined by density" ; mlotst:scale_factor = 0.1f ; mlotst:standard_name = "ocean_mixed_layer_thickness_defined_by_sigma_theta" ; mlotst:unit_long = "Meters" ; mlotst:units = "m" ; mlotst:valid_max = 20000s ; mlotst:valid_min = -20000s ; // global attributes: :Conventions = "CF-1.0" ; :source = "CMEMS IBI-MFC" ; :institution = "Puertos del Estado (PdE) - Mercator-Ocean (MO)" ; :references = "http://marine.copernicus.eu" ; :title = "CMEMS IBI REANALYSIS: HOURLY PHYSICAL PRODUCTS " ; :easting = "longitude" ; :northing = "latitude" ; :domain_name = "IBI12" ; :field_type = "mean" ; :field_date = "20191201" ; :longitude_min = "-19.f" ; :longitude_max = "5.f" ; :latitude_min = "26.f" ; :latitude_max = "56.f" ; :z_min = "0.494025f" ; :z_max = "0.494025f" ; :contact = "mailto: [email protected]" ; :bulletin_date = "2020-12-01" ; :bulletin_type = "Reanalysis" ; }

- cmems_mod_ibi_phy_my_0.083deg-3D_P1D-m

netcdf CMEMS_v5r1_IBI_PHY_MY_PdE_01dav_20191201_20191201_R20201201_RE01 { dimensions: time = UNLIMITED ; // (1 currently) latitude = 361 ; longitude = 289 ; depth = 50 ; variables: float time(time) ; time:axis = "T" ; time:calendar = "gregorian" ; time:long_name = "time" ; time:standard_name = "time" ;



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time:units = "hours since 1950-01-01 00:00:00" ; time:_CoordinateAxisType = "Time" ; float longitude(longitude) ; longitude:standard_name = "longitude" ; longitude:long_name = "Longitude" ; longitude:units = "degrees_east" ; longitude:axis = "X" ; longitude:unit_long = "Degrees East" ; longitude:step = "0.08333f" ; longitude:_CoordinateAxisType = "Lon" ; float latitude(latitude) ; latitude:standard_name = "latitude" ; latitude:long_name = "Latitude" ; latitude:units = "degrees_north" ; latitude:axis = "Y" ; latitude:unit_long = "Degrees North" ; latitude:step = "0.08333f" ; latitude:_CoordinateAxisType = "Lat" ; float depth(depth) ; depth:standard_name = "depth" ; depth:long_name = "Depth" ; depth:units = "m" ; depth:positive = "down" ; depth:axis = "Z" ; depth:unit_long = "Meters" ; depth:_CoordinateAxisType = "Height" ; depth:_CoordinateZisPositive = "down" ; short bottomT(time, latitude, longitude) ; bottomT:standard_name = "sea_water_potential_temperature_at_sea_floor" ; bottomT:long_name = "Sea floor potential temperature" ; bottomT:units = "degrees_C" ; bottomT:add_offset = 10.f ; bottomT:scale_factor = 0.001f ; bottomT:_FillValue = -32767s ; bottomT:unit_long = "degrees_C" ; bottomT:valid_min = -12000s ; bottomT:valid_max = 22000s ; short so(time, depth, latitude, longitude) ; so:standard_name = "sea_water_salinity" ; so:long_name = "Salinity" ; so:units = "1e-3" ; so:add_offset = 20.f ; so:scale_factor = 0.001f ; so:_FillValue = -32767s ; so:unit_long = "Practical Salinity Unit" ; so:valid_min = -20000s ; so:valid_max = 20000s ; short thetao(time, depth, latitude, longitude) ;



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thetao:standard_name = "sea_water_potential_temperature" ; thetao:long_name = "Temperature" ; thetao:units = "degrees_C" ; thetao:add_offset = 10.f ; thetao:scale_factor = 0.001f ; thetao:_FillValue = -32767s ; thetao:unit_long = "degrees_C" ; thetao:valid_min = -12000s ; thetao:valid_max = 22000s ; short uo(time, depth, latitude, longitude) ; uo:standard_name = "eastward_sea_water_velocity" ; uo:long_name = "Eastward velocity" ; uo:units = "m s-1" ; uo:add_offset = 0.f ; uo:scale_factor = 0.001f ; uo:_FillValue = -32767s ; uo:unit_long = "Meters per second" ; uo:valid_min = -3000s ; uo:valid_max = 3000s ; short vo(time, depth, latitude, longitude) ; vo:standard_name = "northward_sea_water_velocity" ; vo:long_name = "Northward velocity" ; vo:units = "m s-1" ; vo:add_offset = 0.f ; vo:scale_factor = 0.001f ; vo:_FillValue = -32767s ; vo:unit_long = "Meters per second" ; vo:valid_min = -3000s ; vo:valid_max = 3000s ; short zos(time, latitude, longitude) ; zos:standard_name = "sea_surface_height_above_geoid" ; zos:long_name = "Sea surface height" ; zos:units = "m" ; zos:add_offset = 0.f ; zos:scale_factor = 0.001f ; zos:_FillValue = -32767s ; zos:unit_long = "Meters" ; zos:valid_min = -10000s ; zos:valid_max = 10000s ; short mlotst(time, latitude, longitude) ; mlotst:_FillValue = -32767s ; mlotst:add_offset = 2000.f ; mlotst:long_name = "Ocean mixed layer thickness defined by density" ; mlotst:scale_factor = 0.1f ; mlotst:standard_name = "ocean_mixed_layer_thickness_defined_by_sigma_theta" ; mlotst:unit_long = "Meters" ; mlotst:units = "m" ; mlotst:valid_max = 20000s ;



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mlotst:valid_min = -20000s ; // global attributes: :Conventions = "CF-1.0" ; :source = "CMEMS IBI-MFC" ; :institution = "Puertos del Estado (PdE) - Mercator-Ocean (MO)" ; :references = "http://marine.copernicus.eu" ; :title = "CMEMS IBI REANALYSIS: DAILY PHYSICAL PRODUCTS " ; :easting = "longitude" ; :northing = "latitude" ; :domain_name = "IBI12" ; :field_type = "mean" ; :field_date = "20191201" ; :longitude_min = "-19.f" ; :longitude_max = "5.f" ; :latitude_min = "26.f" ; :latitude_max = "56.f" ; :z_min = "0.50576f" ; :z_max = "5902.058f" ; :contact = "mailto: [email protected]" ; :bulletin_date = "2020-12-01" ; :bulletin_type = "Reanalysis" ; }

- cmems_mod_ibi_phy_my_0.083deg-3D_P1M-m

netcdf CMEMS_v5r1_IBI_PHY_MY_PdE_01mav_20190101_20190101_R20201201_RE01 { dimensions: time = UNLIMITED ; // (1 currently) latitude = 361 ; longitude = 289 ; depth = 50 ; variables: float time(time) ; time:axis = "T" ; time:calendar = "gregorian" ; time:long_name = "time" ; time:standard_name = "time" ; time:units = "hours since 1950-01-01 00:00:00" ; time:_CoordinateAxisType = "Time" ; float longitude(longitude) ; longitude:standard_name = "longitude" ; longitude:long_name = "Longitude" ; longitude:units = "degrees_east" ; longitude:axis = "X" ; longitude:unit_long = "Degrees East" ; longitude:step = "0.08333f" ; longitude:_CoordinateAxisType = "Lon" ;



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float latitude(latitude) ; latitude:standard_name = "latitude" ; latitude:long_name = "Latitude" ; latitude:units = "degrees_north" ; latitude:axis = "Y" ; latitude:unit_long = "Degrees North" ; latitude:step = "0.08333f" ; latitude:_CoordinateAxisType = "Lat" ; float depth(depth) ; depth:standard_name = "depth" ; depth:long_name = "Depth" ; depth:units = "m" ; depth:positive = "down" ; depth:axis = "Z" ; depth:unit_long = "Meters" ; depth:_CoordinateAxisType = "Height" ; depth:_CoordinateZisPositive = "down" ; short bottomT(time, latitude, longitude) ; bottomT:standard_name = "sea_water_potential_temperature_at_sea_floor" ; bottomT:long_name = "Sea floor potential temperature" ; bottomT:units = "degrees_C" ; bottomT:add_offset = 10.f ; bottomT:scale_factor = 0.001f ; bottomT:_FillValue = -32767s ; bottomT:unit_long = "degrees_C" ; bottomT:valid_min = -12000s ; bottomT:valid_max = 22000s ; short so(time, depth, latitude, longitude) ; so:standard_name = "sea_water_salinity" ; so:long_name = "Salinity" ; so:units = "1e-3" ; so:add_offset = 20.f ; so:scale_factor = 0.001f ; so:_FillValue = -32767s ; so:unit_long = "Practical Salinity Unit" ; so:valid_min = -20000s ; so:valid_max = 20000s ; short thetao(time, depth, latitude, longitude) ; thetao:standard_name = "sea_water_potential_temperature" ; thetao:long_name = "Temperature" ; thetao:units = "degrees_C" ; thetao:add_offset = 10.f ; thetao:scale_factor = 0.001f ; thetao:_FillValue = -32767s ; thetao:unit_long = "degrees_C" ; thetao:valid_min = -12000s ; thetao:valid_max = 22000s ; short uo(time, depth, latitude, longitude) ;



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uo:standard_name = "eastward_sea_water_velocity" ; uo:long_name = "Eastward velocity" ; uo:units = "m s-1" ; uo:add_offset = 0.f ; uo:scale_factor = 0.001f ; uo:_FillValue = -32767s ; uo:unit_long = "Meters per second" ; uo:valid_min = -3000s ; uo:valid_max = 3000s ; short vo(time, depth, latitude, longitude) ; vo:standard_name = "northward_sea_water_velocity" ; vo:long_name = "Northward velocity" ; vo:units = "m s-1" ; vo:add_offset = 0.f ; vo:scale_factor = 0.001f ; vo:_FillValue = -32767s ; vo:unit_long = "Meters per second" ; vo:valid_min = -3000s ; vo:valid_max = 3000s ; short zos(time, latitude, longitude) ; zos:standard_name = "sea_surface_height_above_geoid" ; zos:long_name = "Sea surface height" ; zos:units = "m" ; zos:add_offset = 0.f ; zos:scale_factor = 0.001f ; zos:_FillValue = -32767s ; zos:unit_long = "Meters" ; zos:valid_min = -10000s ; zos:valid_max = 10000s ; short mlotst(time, latitude, longitude) ; mlotst:_FillValue = -32767s ; mlotst:add_offset = 2000.f ; mlotst:long_name = "Ocean mixed layer thickness defined by density" ; mlotst:scale_factor = 0.1f ; mlotst:standard_name = "ocean_mixed_layer_thickness_defined_by_sigma_theta" ; mlotst:unit_long = "Meters" ; mlotst:units = "m" ; mlotst:valid_max = 20000s ; mlotst:valid_min = -20000s ; // global attributes: :Conventions = "CF-1.0" ; :source = "CMEMS IBI-MFC" ; :institution = "Puertos del Estado (PdE) - Mercator-Ocean (MO)" ; :references = "http://marine.copernicus.eu" ; :title = "CMEMS IBI REANALYSIS: MONTHLY PHYSICAL PRODUCTS " ; :easting = "longitude" ; :northing = "latitude" ;



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:domain_name = "IBI12" ; :field_type = "mean" ; :field_date = "20190116" ; :longitude_min = "-19.f" ; :longitude_max = "5.f" ; :latitude_min = "26.f" ; :latitude_max = "56.f" ; :z_min = "0.50576f" ; :z_max = "5902.058f" ; :contact = "mailto: [email protected]" ; :bulletin_date = "2020-12-01" ; :bulletin_type = "Reanalysis" ; }

- cmems_mod_ibi_phy_my_0.083deg-3D_static

This dataset only contains 3 files.

netcdf IBI-MFC_005_002_mask_bathy { dimensions: latitude = 361 ; longitude = 289 ; depth = 50 ; variables: float longitude(longitude) ; longitude:axis = "X" ; longitude:standard_name = "longitude" ; longitude:units = "degrees_east" ; longitude:step = "0.08333f f" ; float latitude(latitude) ; latitude:axis = "Y" ; latitude:standard_name = "latitude" ; latitude:units = "degrees_north" ; latitude:step = "0.08333f f" ; byte mask_thetao(depth, latitude, longitude) ; mask_thetao:long_name = "Land-sea mask: 1 = sea ; 0 = land" ; mask_thetao:standard_name = "sea_binary_mask" ; mask_thetao:units = "1" ; byte mask_uo(depth, latitude, longitude) ; mask_uo:long_name = "Land-sea mask: 1 = sea ; 0 = land" ; mask_uo:standard_name = "sea_binary_mask" ; mask_uo:units = "1" ; byte mask_vo(depth, latitude, longitude) ; mask_vo:long_name = "Land-sea mask: 1 = sea ; 0 = land" ; mask_vo:standard_name = "sea_binary_mask" ; mask_vo:units = "1" ; float depth(depth) ; depth:standard_name = "depth" ;



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depth:units = "m" ; depth:positive = "down" ; depth:axis = "Z" ; float deptho(latitude, longitude) ; deptho:_FillValue = -32767s ; deptho:long_name = "Bathymetry" ; deptho:standard_name = "sea_floor_depth_below_geoid" ; deptho:units = "m" ; // global attributes: :Conventions = "CF-1.0" ; :domain_name = "IBI12" ; :contact = "mailto: [email protected]" ; :references = "http://marine.copernicus.eu" ; :credit = "E.U. Copernicus Marine Service Information (CMEMS)" ; :licence = "http://marine.copernicus.eu/services-portfolio/service-commitments-and-licence/" ; :producer = "CMEMS - IBI Monitoring and Forecasting Centre" ; :area = "IBI" ; :title = "Static files for product IBI_MULTIYEAR_PHY_005_002" ; :product = "IBI_MULTIYEAR_PHY_005_002" ; :product_user_manual = "http://marine.copernicus.eu/documents/PUM/CMEMS-IBI-PUM-005-002.pdf" ;

:dataset = "cmems _mod_ibi_phy_my_0.083deg-3D_static" ;

:institution = "Nologin-MeteoFrance-Puertos del Estado" ; :quality_information_document = "http://marine.copernicus.eu/documents/QUID/CMEMS-IBI-QUID-005-002.pdf" ; } netcdf IBI-MFC_005_001_coordinates { dimensions: latitude = 361 ; longitude = 289 ; depth = 50 ; variables: float e2t(depth,latitude, longitude) ; e2t:_FillValue = -32767s ; e2t:long_name = "Cell dimension along Y axis" ; e2t:units = "m" ; float e1t(depth,latitude, longitude) ; e1t:_FillValue = -32767s ; e1t:long_name = "Cell dimension along X axis" ; e1t:units = "m" ; float e3t(depth latitude, longitude) ; e3t:_FillValue = -32767s ; e3t:long_name = "Cell dimension along Z axis" ;



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e3t:units = "m" ; float longitude(longitude) ; longitude:axis = "X" ; longitude:standard_name = "longitude" ; longitude:units = "degrees_east" ; longitude:step = "0.08333f f" ; float latitude(latitude) ; latitude:axis = "Y" ; latitude:standard_name = "latitude" ; latitude:units = "degrees_north" ; latitude:step = "0.08333f f" ; float depth(depth) ; depth:standard_name = "depth" ; depth:units = "m" ; depth:positive = "down" ; depth:axis = "Z" ; // global attributes: :Conventions = "CF-1.0" ; :domain_name = "IBI12" ; :contact = "mailto: [email protected]" ; :references = "http://marine.copernicus.eu" ; :credit = "E.U. Copernicus Marine Service Information (CMEMS)" ; :licence = "http://marine.copernicus.eu/services-portfolio/service-commitments-and-licence/" ; :producer = "CMEMS - IBI Monitoring and Forecasting Centre" ; :area = "IBI" ; :title = "Static files for product IBI_MULTIYEAR_PHY_005_002" ; :product = "IBI_MULTIYEAR_PHY_005_002" ; :product_user_manual = "http://marine.copernicus.eu/documents/PUM/CMEMS-IBI-PUM-005-002.pdf" ;


:institution = "Nologin-MeteoFrance-Puertos del Estado" ; :quality_information_document = "http://marine.copernicus.eu/documents/QUID/CMEMS-IBI-QUID-005-002.pdf" ; }

netcdf IBI-MFC_005_001_mdt { dimensions: latitude = 361 ; longitude = 289 ; variables: float mdt(latitude, longitude) ; mdt:long_name = "Mean dynamic topography" ; mdt:standard_name = "sea_surface_height_above_geoid" ; mdt:units = "m" ;



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mdt:_FillValue = -32767s ; mdt:cell_methods = "area: mean" ; float longitude(longitude) ; longitude:axis = "X" ; longitude:standard_name = "longitude" ; longitude:units = "degrees_east" ; longitude:step = "0.08333f f" ; float latitude(latitude) ; latitude:axis = "Y" ; latitude:standard_name = "latitude" ; latitude:units = "degrees_north" ; latitude:step = "0.08333f f" ;

// global attributes: :Conventions = "CF-1.0" ; :domain_name = "IBI12" ; :contact = "mailto: [email protected]" ; :references = "http://marine.copernicus.eu" ; :credit = "E.U. Copernicus Marine Service Information (CMEMS)" ; :licence = "http://marine.copernicus.eu/services-portfolio/service-commitments-and-licence/" ; :producer = "CMEMS - IBI Monitoring and Forecasting Centre" ; :area = "IBI" ; :title = "Static files for product IBI_MULTIYEAR_PHY_005_002" ; :product = "IBI_MULTIYEAR_PHY_005_002" ; :product_user_manual = "http://marine.copernicus.eu/documents/PUM/CMEMS-IBI-PUM-005-002.pdf" ;


:institution = "Nologin-MeteoFrance-Puertos del Estado" ; :quality_information_document = "http://marine.copernicus.eu/documents/QUID/CMEMS-IBI-QUID-005-002.pdf" ; }

The previous file structures shown as example correspond to the complete IBI files, which are downloaded through DGF or FTP. However, when data from the IBI forecast product are downloaded through the Subsetter interface, the file map and structure change slightly, and it is dependent on the parameter selection made by the user in the specific data request.



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V REFERENCES

Barnier, B., Madec, G., Penduff, T., Molines, J.-M., Treguier, A.-M., Le Sommer, J., Beckmann, A., Biastoch, A., Boning, C., Dengg, J., Derval, C., Durand, E., Gulev, S., Remy, E., Talandier, C., Theetten, S., Maltrud, M., McClean, J., and De Cuevas, B.: Impact of partial steps and momentum advection schemes in a global ocean circulation model at eddy-permitting resolution, Ocean Dynam., 56, 543–567, doi:10.1007/s10236-006-0082-1, 2006.

Becker, J. J., Sandwell, D. T., Smith, W. H. F., Braud, J., B. Binder, B., Depner, J., Fabre, D., Factor, J., Ingalls, S., Kim, S.-H., Ladner, R., Marks, K., Nelson, S., Pharaoh, A., Trimmer, R., Von Rosenberg, J., Wallace, G., and Weatherall, P.: Global bathymetry and elevation data at 30 arc seconds resolution: SRTM30 PLUS, Mar Geod., 32, 355–371, 2009.

Benkiran, M. and Greiner, E.: Impact of the Incremental Analysis Updates on a Real-Time System of the North Atlantic Ocean, Journal of Atmospheric and Oceanic Technology 25(11):2055-2073, 2008.

Bloom, S.C., Takas, L.L., Da Silva, A.M., and Ledvina, D. 1996: Data assimilation using Incremental analysis updates. Monthly Weather Review, 124, 1256–1271.

Carrère, L. and Lyard, F.: Modelling the barotropic response of the global ocean to atmospheric wind and pressure forcing - comparisons with observations, Geophys. Res. Let., 30(6), pp 1275, 2003.

Desroziers, G., Berre, L., Chapnik, B., and Polli, P., 2005: Diagnosis of observation, background and analysis-error statistics in observation space, Q. J. R. Meteorol. Soc., 131, pp. 3385–3396, doi: 10.1256/qj.05.108.

Dibarboure G. M.-I. Pujol, F. Briol , P. Y. Le Traon , G. Larnicol , N. Picot , F. Mertz , M. Lellouche, J.-M., Le Galloudec, O., Drévillon, M., Régnier, C., Greiner, E., Garric, G., Ferry, N., Desportes, C., Testut, C.-E., Bricaud, C., Bourdallé-Badie, R., Tranchant, B., Benkiran, M., Daudin, A. and De Nicola, C. : Evalution of global monotoring and forecasting systems at Mercator Océan. Ocean Sci., 9, 57-81, 2013.

Egbert GD and Erofeeva SY. 2002. Efficient Inverse Modeling of Barotropic Ocean Tides. J. Atmos. Oceanic Technology. 19: 183–204

Ide, K., Courtier, P., Ghil, M., and Lorenc, A.C (1997): Unified notation for data assimilation: Operational, sequential and variational, J. Met. Soc. Japan, 75, 181-189.

Large, W. G. and Yeager S. G.: Diurnal to decadal global forcing for ocean and sea-ice models: the data sets and flux climatologies, NCAR Technical Note: NCAR/TN-460+STR, CGD Division of the National Center for Atmospheric Research, 2004.

Lellouche, J.-M., Le Galloudec, O., Drévillon, M., Régnier, C., Greiner, E., Garric, G., Ferry, N., Desportes, C., Testut, C.-E., Bricaud, C., Bourdallé-Badie, R., Tranchant, B., Benkiran, M., Daudin, A. and De Nicola, C. : Evalution of global monotoring and forecasting systems at Mercator Océan. O

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For Atlantic -Iberian Biscay Irish- Ocean Physics ......Atlantic -Iberian Biscay Irish- area (generated and provided by the CMEMS IBI-MFC). This document comprises a description of