myoecan user manual · (dataset-armor-3d-rep-weekly-v3-1-myocean,...

PRODUCT USER MANUAL

For Global Ocean Observation-based Products

GLOBAL_REP_PHYS_001_013

Issue: 1.5

Contributors: V Rosmorduc, F. Mertz, S. Guinehut , S. Mulet

CMEMS version scope : V2

Approval Date :

PUM for Global Ocean Observation-based Products


Ref :CMEMS-GLO-PUM-001-013

Date : April 2016

Issue : 1.5

© EU Copernicus Marine Service – Public / 17

CHANGE RECORD

Issue Date § Description of Change Author Checked By

1.0

15/12/14

Creation

F. Mertz

1.1 17/12/14 MyOF modifications Y. Drillet Y. Drillet

L. Crosnier

1.2 01/05/15 all Change format to fit CMEMS graphical rules

L. Crosnier

1.3 23/12/15 all Remove information related to the GLOBAL_ANALYSIS _PHYS_001_016 product (old product)

S. Mulet

1.4 11/03/16 header Minor modification N. Verbrugge

1.5 04/04/16 IV.5.1 SSALTO => CMEMS N. Verbrugge




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TABLE OF CONTENTS

I INTRODUCTION ......................................................................................................................................... 6

I.1 Summary .............................................................................................................................................. 6

II HOW TO DOWNLOAD A PRODUCT ......................................................................................................... 7

II.1 Download a product through the Web Portal Subsetter Service .................................................... 7

II.2 Download a product through the Web Portal Directgetfile Service ................................................ 7

II.3 Download a product through the Web Portal Ftp Service............................................................... 7

III DESCRIPTION OF THE PRODUCT SPECIFICATION ...................................................................... 8

III.1 General Information............................................................................................................................ 8

III.2 Details of datasets ................................................................................................................................ 9

IV NOmenclature of files ................................................................................................................................. 10

IV.1 Nomenclature of files when downloaded through the Web Portal Subsetter Service ................. 10

IV.2 Nomenclature of files when downloaded through the Web Portal Directgetfile and Ftp Service

10

IV.3 Domain coverage ............................................................................................................................... 11

IV.4 Vertical Levels ................................................................................................................................... 11

IV.5 Processing ........................................................................................................................................... 11 IV.5.1 Input data ......................................................................................................................... 11 IV.5.2 Method .............................................................................................................................. 11

V file format .................................................................................................................................................... 14

V.1 Netcdf .................................................................................................................................................. 14

V.2 Structure and semantic of netCDF maps files ................................................................................. 14

V.3 Reading software ............................................................................................................................... 17




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GLOSSARY AND ABBREVIATIONS

AMSR Advanced Microwave Scanning Radiometer

AVHRR Advanced Very High Resolution Radiometer

CF Climate Forecast (convention for NetCDF)

CTD Conductivity-Temperature-Depth

DT Delayed Time

FTP File Transfer Protocol

Meridional Velocity West to East component of the horizontal velocity vector

MFC Monitoring and Forecasting Centre

NetCDF Network Common Data Form

NOAA National Oceanic and Atmospheric Administration

NRT Near Real Time

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)

RD Reference Document

RMS Root mean square

S Salinity

SLA Sea Level Anomaly

SSH Sea surface height

SSS Sea surface salinity.

SST Sea Surface Temperature

T Temperature

XBT eXpendable Bathy-Thermograph

Zonal Velocity South to North component of the horizontal velocity vector

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

Directgetfile CMEMS service tool (FTP like) to download a NetCDF file




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REFERENCE DOCUMENTS

RD 1 Guinehut S., P.-Y. Le Traon, G. Larnicol and S. Philipps, Combining Argo and remote-sensing data to estimate the ocean three-dimensional temperature fields – a first approach based on simulated observations, 2004 / J. Mar. Sys., 46, 85-98.

RD 2 Guinehut S., P.-Y. Le Traon and G. Larnicol, What can we learn from Global Altimetry/Hydrography comparisons?, 2006 / Geophys. Res. Lett, 33, L10604, doi: 10.1029/2005GL025551.

RD 3 Dhomps A.-L., S. Guinehut, P.Y. Le Traon and G. Larnicol, 2011: A global comparison of Argo and satellite altimetry observations, Ocean Science, Vol.7, pp. 175-183, SRef-ID : 1812-0792/os/2011-7-175.

RD 4 Bretherton, F. P., R. E. Davis and C. B. Fandry, A technique for objective analysis and design of oceanographic experiments applied to MODE-73, 1976 / Deep-Sea Res., 23, 559-582.

RD 5 Gaillard, F., R. Charraudeau, New climatology and statistics over the global Ocean, 2008 / MERSEA-WP05-CNRS-STR- 001-1A

RD 6 Mulet, S., M.-H. Rio, A. Mignot, S. Guinehut and R. Morrow, 2012: A new estimate of the global 3D geostrophic ocean circulation based on satellite data and in-situ measurements. Deep-Sea Res. II., 77-80, 70-81, doi:10.1016/j.dsr2.2012.04.012.

RD 7 Rio M.-H., S. Guinehut and G. Larnicol, 2011: The New CNES-CLS09 global Mean Dynamic Topography computed from the combination of GRACE data, altimetry and in-situ measurements. J. Geophys. Res., 116, C07018, doi:10.1029/2010JC006505

RD 8 Guinehut S., A.-L. Dhomps, G. Larnicol and P.-Y. Le Traon, 2012: High resolution 3D temperature and salinity fields derived from in situ and satellite observations. Ocean Sci., 8, 845-857, doi:10.5194/os-8-845-2012.




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I INTRODUCTION

I.1 Summary

This guide describes the data product files from the GLO-CLS-TOULOUSE-FR PU, what data services are available to access them, and how to use the files and services.

The product described here is GLOBAL_REP_PHYS_001_013 product. It contains two datasets (dataset-armor-3d-rep-weekly-v3-1-myocean, dataset-armor-3d-rep-monthly-v3-1-myocean): delayed time global 3D temperature, salinity, geopotential height and geostrophic current fields defined on a 1/4° regular grid, from the surface down to 5500-m depth at a weekly period and at a monthly period.

Those products are a combination between satellite and in-situ data, processed in three steps:

(1) satellite data (SLA + SST) are projected onto the vertical via a multiple linear regression method and covariances deduced from historical observations. This step gives synthetical fields,

(2) combination between these synthetic fields with T/S in-situ profiles via an optimal interpolation method. This leads to combined fields.

(3) use of the thermal wind equation to combine absolute geostrophic current fields from satellite altimetry with the combined 3D T/S fields. This last step generates global 3D geostrophic current fields.




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II HOW TO DOWNLOAD A PRODUCT

II.1 Download a product through the Web Portal Subsetter Service

You first need to register. Please find below the registration form:

http://marine.copernicus.eu/web/56-user-registration-form.php

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

Using the subsetter you can extract the product on a specific area of your interest, select which variable(s) you need and over a selected time period.

II.2 Download a product through the Web Portal Directgetfile Service

You first need to register. Please find below the registration form: http://marine.copernicus.eu/web/56-user-registration-form.php

Once registered, the 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 Directgetfile Service.

Using the direct get file, you will get the entire file.

II.3 Download a product through the Web Portal Ftp Service

You first need to register. Please find below the registration form: http://marine.copernicus.eu/web/56-user-registration-form.php

Once registered, the 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.

Using the ftp, you will get the entire file.


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








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III DESCRIPTION OF THE PRODUCT SPECIFICATION

III.1 General Information

Product Specification Customer Name


Geographical coverage Global (82°S, 90°N, 0-360°E)

Variables Temperature, Salinity, Geopotential Height, Eastward and Northward geostrophic Velocities

Available time series 06/01/1993 – 24/12/2014

Note: REPROCESSED products are updated regularly (once per year).

Temporal resolution Each Wednesday mean fields , monthly mean fields

Target delivery time -

Delivery mechanism Information Service (Subsetter, Directgetfile and MFTP)

Horizontal resolution 1/4° on a regular grid

Number of vertical levels

33 levels from 0 to 5500-m depth

Format Netcdf CF3.0

Table 1: GLOBAL_REP_PHYS_001_013 product specification customer name

Detailed information on the systems and products are on web site: http://marine.copernicus.eu.

http://marine.copernicus.eu/

http://marine.copernicus.eu/




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III.2 Details of datasets


DATASETS VARIABLES AND UNIT NAME OF VARIABLES IN THE NETCDF FILE

dataset-armor-3d-rep-weekly-v3-1-myocean

Salinity [PSU]

Temperature [degC]

Height above geoid [m]

Eastward Geostrophic Velocities [m/s]

Northward Geostrophic Velocities [m/s]

salinity

temperature

height

zvelocity

mvelocity

dataset-armor-3d-rep-monthly-v3-1-myocean

Salinity [PSU]

Temperature [degC]

Height above geoid [m]

Eastward Geostrophic Velocities [m/s]

Northward Geostrophic Velocities [m/s]

salinity

temperature

height

zvelocity

mvelocity

Table 2: List of the datasets (column 1), of the variable for each dataset (column 2) and their names

in the NetCDF files (column 3) for GLOBAL_REP_PHYS_001_013




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IV NOMENCLATURE OF FILES

The nomenclature of the downloaded files differs on the basis of the chosen download mechanism Subsetter, Directgetfile and FTP service.

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

GLOBAL_REP_PHYS_001_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: dataset-armor-3d-rep-v3-1-myocean-nnnnnnnnnnnnn.nc

where :

. 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:

dataset-armor-3d-rep-v3-1-myocean_1318943845185.nc

IV.2 Nomenclature of files when downloaded through the Web Portal Directgetfile and Ftp Service

GLOBAL_REP_PHYS_001_013 files nomenclature when downloaded through the CMEMS Web Portal Directgetfile and CMEMS FTP is based as follows:

For the weekly dataset (dataset-armor-3d-rep-weekly-v3-1-myocean):

ARMOR3D_REPv3-1_DATE1_DATE2.nc

DATE1: YYYYMMDD corresponds to the date of the field

DATE2: YYYYMMDD corresponds to the date of the production

For the monthly dataset (dataset-armor-3d-rep-monthly-v3-1-myocean):

ARMOR3D_REPv3-1_DATE1_DATE2.nc

DATE1: YYYYMMDD corresponds to the date of the field where DD is 15

DATE2: YYYYMMDD corresponds to the date of the production




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IV.3 Domain coverage

The coverage of the data is global (82°S, 90°N, 0-360°W) and the data are projected on a 1/4° regular grid.

IV.4 Vertical Levels

GLOBAL_REP_PHYS_001_013 products are computed on 33 levels from 0 to 5500-m depth. The levels are the following (in meters):

0, 10, 20, 30, 50, 75, 100, 125, 150, 200, 250, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1750, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500

IV.5 Processing

IV.5.1 Input data

Five sources of data are used:

- In-situ T and S profiles are from the IN-SITU TAC including Argo profiling floats, XBT, CTD and moorings;

- ARV11 climatology computed at ifremer (http://wwz.ifremer.fr/lpo/SO-Argo/Products/Global-Ocean-T-S/ARV11-climatology)

- Altimeter sea level anomalies (SLA) are from CMEMS (SL TAC – SEALEVEL_GLO_SLA_MAP_L4_REP_OBSERVATIONS_008_027) and are weekly combined maps of all processed altimeters

- Mean Dynamic Topography CNES-CLS13.

- SST data are from daily Reynolds analyses with a 1/4° horizontal resolution, combining AVHRR and in-situ observations (no more AMSR since October 2011) and distributed by the National Climatic Data Center at NOAA (http://www.ncdc.noaa.gov/oa/climate/research/sst/oi-daily.php).

IV.5.2 Method

For the temperature (T) and salinity (S) fields available in near real time and in delayed time, the method used has been first developed using simulated data sets [RD 1] and has two steps [RD 8].

The first step of the method consists in deriving synthetic temperature (T) profiles from the surface down to 1500-meter depth from altimeter and SST data through a multiple linear regression method and covariances calculated from historical data. For synthetic salinity (S) profiles, the method uses only altimeter data. Pre-processing of altimeter SLA includes the extraction of the steric part of the SLA using regression coefficients deduced from an altimeter/in-situ comparison study [RD 2, RD 3].

The second step of the method consists in combining the synthetic profiles with in-situ temperature and salinity profiles using an optimal interpolation method [RD 4]. To gain maximum benefit from the qualities of both data sets, namely the accurate information given by in-situ T/S profiles and the mesoscale variability given by the T/S synthetic profiles, a precise statistical description of the errors of these observations has been introduced in the optimal interpolation method. For the in-situ profiles, since these observations are considered almost perfect, a very low white noise is applied. For the synthetic profiles, simulating remote-sensing (altimeter and SST) observations, since these observations are not direct measurements but are derived from the regression method, correlated errors have to be applied to correct long-wavelength errors or biases present in the synthetic fields and introduced by the regression method.

http://wwz.ifremer.fr/lpo/SO-Argo/Products/Global-Ocean-T-S/ARV11-climatology

http://wwz.ifremer.fr/lpo/SO-Argo/Products/Global-Ocean-T-S/ARV11-climatology

http://www.ncdc.noaa.gov/oa/climate/research/sst/oi-daily.php

http://www.ncdc.noaa.gov/oa/climate/research/sst/oi-daily.php




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Analyses are performed in near real time and in delayed time at a weekly period on each Levitus vertical level from the surface down to 1500-meter depth.

An example of the input and output fields is given on Figure 1 for the 4th of July 2010. Thanks to the

mesoscale structures available in the altimetry and SST fields, the synthetic estimate shows also mesoscale structures in most part of the ocean with T anomalies ranging from -2 to 2 °C at 100-meter depth (Figure 1). The combination of the synthetic estimates with all available in-situ temperature allows correcting the field in some regions like in the North-East Indian Ocean where the in-situ temperature are much colder than the synthetic ones. Amplitudes of the combined fields are thus more similar to the in-situ observations but with still small scale structure.

The T/S fields are completed from 1500 to 5500 meter depth using the T/S climatology. Geopotential height and geostrophic current fields are additionally available. They are calculated using the thermal wind equation with a reference level at the surface to combine absolute current fields at the surface from satellite altimetry with the combined T/S fields [RD 6]. The surface currents are calculated by geostrophy from SLA and MDT CNES-CLS13. As the CNES-CLS13 Mean Dynamic Topographies used to calculate the absolute current fields at the surface are not defined for the Black and Red Seas [RD 7], the 3D geostrophic current fields are also not defined for those areas.

Altimeter SLA – 04/07/2007

SST – 04/07/2007

Arivo climatology for July

Synthetic T anomalies at 100-m depth – 04/07/2007

In-situ temperature anomalies at 100-m around the 04/07/2007

T anomalies at 100-m depth from the combined estimates – 04/07/2007




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Figure 1: Input and outputs from the system calculating T and S fields for the 4th of July 2007.




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V FILE FORMAT

V.1 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.

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.

V.2 Structure and semantic of netCDF maps files

For ARMOR3D_REPv3-1_YYYYMMDD_YYYYMMDD.nc

netcdf ARMOR3D_REPv3-1_20050824_20130910 { dimensions: longitude = 1440 ; latitude = 689 ; depth = 33 ; variables: float longitude(longitude) ; longitude:axis = "X" ; longitude:long_name = "longitude" ; longitude:standard_name = "longitude" ; longitude:step = 0.25f ; longitude:unit_long = "degrees east" ; longitude:units = "degrees_east" ; float latitude(latitude) ; latitude:axis = "Y" ; latitude:long_name = "latitude" ; latitude:standard_name = "latitude" ; latitude:step = 0.25f ; latitude:unit_long = "degrees north" ; latitude:units = "degrees_north" ; short depth(depth) ; depth:axis = "Z" ; depth:long_name = "depth" ; depth:positive = "down" ; depth:standard_name = "depth" ;




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depth:unit_long = "meter" ; depth:units = "m" ; short height(depth, latitude, longitude) ; height:_FillValue = 32767s ; height:long_name = "absolute height from SURCOUF3D" ; height:scale_factor = 0.001 ; height:standard_name = "height_above_geoid" ; height:unit_long = "meter" ; height:units = "m" ; height:valid_range = -20000s, 20000s ; short mvelocity(depth, latitude, longitude) ; mvelocity:_FillValue = 32767s ; mvelocity:long_name = "meridional velocity from SURCOUF3D" ; mvelocity:scale_factor = 0.001 ; mvelocity:standard_name = "northward_sea_water_velocity" ; mvelocity:unit_long = "meter per second" ; mvelocity:units = "m/s" ; mvelocity:valid_range = -4000s, 4000s ; short salinity(depth, latitude, longitude) ; salinity:_FillValue = 32767s ; salinity:add_offset = 20. ; salinity:long_name = "salinity from ARMOR3D" ; salinity:scale_factor = 0.001 ; salinity:standard_name = "sea_water_salinity" ; salinity:unit_long = "practical salinity unit" ; salinity:units = "1e-3" ; short temperature(depth, latitude, longitude) ; temperature:_FillValue = 32767s ; temperature:add_offset = 20. ; temperature:long_name = "temperature from ARMOR3D" ; temperature:scale_factor = 0.001 ; temperature:standard_name = "sea_water_temperature" ; temperature:unit_long = "degree Celsius" ; temperature:units = "degC" ; short zvelocity(depth, latitude, longitude) ; zvelocity:_FillValue = 32767s ; zvelocity:long_name = "zonal velocity from SURCOUF3D" ; zvelocity:scale_factor = 0.001 ; zvelocity:standard_name = "eastward_sea_water_velocity" ; zvelocity:unit_long = "meter per second" ; zvelocity:units = "m/s" ; zvelocity:valid_range = -4000s, 4000s ; // global attributes: :description = "TSHUV Global Ocean Obervation-based Reprocessed Products" ; :title = "ARMOR3D_REP V3.1 weekly" ; :conventions = "CF-1.0" ; :institution = "CLS" ; :domain_name = "GLO" ; :history = "2013-09-12 23:51:26 ARMOR3D_REP V3.1 weekly netCDF creation" ; }

For ARMOR3D_REPv3-1_YYYYMM15_YYYYMMDD.nc

netcdf ARMOR3D_REPv3-1_20041015_20130910 { dimensions: longitude = 1440 ; latitude = 689 ; depth = 33 ; variables: float longitude(longitude) ; longitude:axis = "X" ;




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longitude:long_name = "longitude" ; longitude:standard_name = "longitude" ; longitude:step = 0.25f ; longitude:unit_long = "degrees east" ; longitude:units = "degrees_east" ; float latitude(latitude) ; latitude:axis = "Y" ; latitude:long_name = "latitude" ; latitude:standard_name = "latitude" ; latitude:step = 0.25f ; latitude:unit_long = "degrees north" ; latitude:units = "degrees_north" ; short depth(depth) ; depth:axis = "Z" ; depth:long_name = "depth" ; depth:positive = "down" ; depth:standard_name = "depth" ; depth:unit_long = "meter" ; depth:units = "m" ; short height(depth, latitude, longitude) ; height:_FillValue = 32767s ; height:long_name = "absolute height from SURCOUF3D" ; height:scale_factor = 0.001 ; height:standard_name = "height_above_geoid" ; height:unit_long = "meter" ; height:units = "m" ; height:valid_range = -20000s, 20000s ; short mvelocity(depth, latitude, longitude) ; mvelocity:_FillValue = 32767s ; mvelocity:long_name = "meridional velocity from SURCOUF3D" ; mvelocity:scale_factor = 0.001 ; mvelocity:standard_name = "northward_sea_water_velocity" ; mvelocity:unit_long = "meter per second" ; mvelocity:units = "m/s" ; mvelocity:valid_range = -4000s, 4000s ; short salinity(depth, latitude, longitude) ; salinity:_FillValue = 32767s ; salinity:add_offset = 20. ; salinity:long_name = "salinity from ARMOR3D" ; salinity:scale_factor = 0.001 ; salinity:standard_name = "sea_water_salinity" ; salinity:unit_long = "practical salinity unit" ; salinity:units = "1e-3" ; short temperature(depth, latitude, longitude) ; temperature:_FillValue = 32767s ; temperature:add_offset = 20. ; temperature:long_name = "temperature from ARMOR3D" ; temperature:scale_factor = 0.001 ; temperature:standard_name = "sea_water_temperature" ; temperature:unit_long = "degree Celsius" ; temperature:units = "degC" ; short zvelocity(depth, latitude, longitude) ; zvelocity:_FillValue = 32767s ; zvelocity:long_name = "zonal velocity from SURCOUF3D" ; zvelocity:scale_factor = 0.001 ; zvelocity:standard_name = "eastward_sea_water_velocity" ; zvelocity:unit_long = "meter per second" ; zvelocity:units = "m/s" ; zvelocity:valid_range = -4000s, 4000s ; // global attributes: :title = "\'ARMOR3D_REP V3.1 monthly\'" ; :description = "\'TSHUV Global Ocean Obervation-based Reprocessed Products\'" ;




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:conventions = "CF-1.0" ; :institution = "CLS" ; :domain_name = "GLO" ; :history = "2013-09-14 13:45:06 \'ARMOR3D_REP V3.1 monthly\' netCDF creation" ; }

V.3 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…

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

http://nco.sourceforge.net/

myoecan user manual · (dataset-armor-3d-rep-weekly-v3-1-myocean,...

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