product user manual...altimeter mean sea level daily evolution (filtered and unfiltered) estimated...

PRODUCT USER MANUAL

Sea Level Ocean Monitoring Indicators for:

GLOBAL_OMI_SL_area_averaged_anomalies

GLOBAL_OMI_SL_regional_trends

BALTIC_OMI_SL_area_averaged_anomalies

BLKSEA_OMI_SL_area_averaged_anomalies

IBI_OMI_SL_area_averaged_anomalies

MEDSEA_OMI_SL_area_averaged_anomalies

NORTHEWESTSHELF_OMI_SL_area_averaged_anomalies

Issue: 2.3

Contributors: Jean-François Legeais

Approval Date: 16 January 2020

PUM for CMEMS Ocean Monitoring Indicator

Sea Level

Ref: CMEMS-OMI-SEALEVEL-PUM

Date : 16/01/2020

Issue : 2.3

© EU Copernicus Marine Service Environment Monitoring Service – Public / 15

CHANGE RECORD

Issue Date § Description of Change Author Validated By

1.0 02/02/2018 All Creation of the document JF Legeais

2.0 26/07/2018 All New supporting material, new regional MSL. Use of the reprocessed DUACS DT-2018 products with updated temporal coverage

JF Legeais

2.1 25/01/2019 ALL Evolution after review comments from MO JF Legeais

2.2 09/10/2019 II, III Evolution following the update of the time series

JF Legeais

2.3 16/01/2020 II.1, II.2

Addition of global mean sea level corrected for TOPEX-A drift.

JF Legeais C.Derval


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TABLE OF CONTENTS

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

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

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

II DESCRIPTION OF THE PRODUCT SPECIFICATION .......................................................................... 6

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

II.2 Details of the datasets ................................................................................................................................ 9

II.3 Product System Description .................................................................................................................... 12

II.4 How to download a product .................................................................................................................... 12

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

III FILES NOMENCLATURE and FORMAT ........................................................................................... 13

III.1 Nomenclature of files when downloaded through the CMEMS FTP Services ................................. 13

III.2 File Format: format name ..................................................................................................................... 13

III.3 File size .................................................................................................................................................... 14

III.4 Reading Softwares .................................................................................................................................. 14

IV References .................................................................................................................................................... 15


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GLOSSARY AND ABBREVIATIONS

CMEMS Copernicus Marine Environment Monitoring Service

MSL Mean Sea Level

NetCDF Network Common Data Form

OMI Ocean Monitoring Indicator

PUM Product User Manual

QUID Quality Information Document


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I INTRODUCTION

I.1 Summary

This document is the user manual for the CMEMS Sea Level Ocean Monitoring Indicators (OMI) including different products and associated datasets.

The products are published on the CMEMS dissemination server after automatic and delayed-mode quality controls. The products are available online and disseminated through the CMEMS Information System. Files downloaded are in NetCDF format and follow CF-1.7 convention.

In addition, supporting material is provided in the online catalogue including the regional mean sea level anomalies during the last year of the record. Only the figure is provided.

Disclaimer: The quality of the product may vary during the proposed time series depending on the possible update of the system.

The different sea level OMI products are described in the Quality Information Document (QUID) CMEMS-OMI-SEALEVEL-QUID.pdf (http://cmems-resources.cls.fr/documents/QUID/CMEMS-OMI-QUID-GLO-SL.pdf). See also News flash. More detailed information can be obtained from http://marine.copernicus.eu/services-portfolio/contact-us/

History of change

02/02/2018 Publication of OMI Sea Level products

26/07/2018 Description of the new supporting material, new regional Mean Sea Level. Use of reprocessed DUACS DT-2018 products and updated temporal coverage.

25/01/2019 Evolution after review comments from MO

09/10/2019 Evolution following the update of the time series

http://cmems-resources.cls.fr/documents/QUID/CMEMS-OMI-QUID-GLO-SL.pdf


http://marine.copernicus.eu/services-portfolio/contact-us/


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II DESCRIPTION OF THE PRODUCT SPECIFICATION

II.1 General Information about the products

Product(s) name GLOBAL_OMI_SL_area_averaged_anomalies

Geographical coverage Global Ocean

Variables Filtered and unfiltered time series of altimeter sea level anomalies (sea surface heights above sea level), adjusted from annual and semi-annual signals and the same filtered and unfiltered timeseries corrected for the TOPEX-A instrumental drift during 1993-1998

Update frequency Once per year

Available time series 1993-01-01 to about 5-6 months delay with present time

Delivery mechanism FTP

Temporal resolution Daily

Integration depth (for example..)

Surface

Format NetCDF CF1.7

Product(s) name GLOBAL_OMI_SL_regional trends

Geographical coverage Global Ocean

Variables Map of the altimeter regional sea level trends (sea surface heights above sea level)




Temporal resolution Time integrated


Surface


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Format NetCDF CF1.7

Product(s) name BALTIC_OMI_SL_area_averaged_anomalies

Geographical coverage Baltic Sea

Variables Filtered and unfiltered time series of altimeter sea level anomalies (sea surface heights above sea level), adjusted from annual and semi-annual signals.






Surface

Format NetCDF CF1.7

Product(s) name BLKSEA_OMI_SL_area_averaged_anomalies

Geographical coverage Black Sea







Surface

Format NetCDF CF1.7


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Product(s) name IBI_OMI_SL_area_averaged_anomalies

Geographical coverage Iberia-Biscay-Ireland







Surface

Format NetCDF CF1.7

Product(s) name MEDSEA_OMI_SL_area_averaged_anomalies

Geographical coverage Mediterranean Sea







Surface

Format NetCDF CF1.7


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Product(s) name NORTHWESTSHELF_OMI_SL_area_averaged_anomalies

Geographical coverage North-West Shelf







Surface

Format NetCDF CF1.7

Detailed information on the systems and products are on CMEMS web site:


II.2 Details of the datasets

For each product, one table with details of datasets content

GLOBAL_OMI_SL_area_averaged_anomalies

glo

bal_

om

i_sl_

are

a_avera

ged

_an

om

alies

Altimeter mean sea level daily evolution (filtered and unfiltered) estimated in the global ocean derived from the average of the gridded sea level maps weighted by the cosine of the latitude. The timeseries is low-pass filtered, the annual and semi-annual periodic signals are adjusted. The curves are corrected for the GIA using the ICE5G-VM2 GIA model (Peltier, 2004).

sla_filtered [m] Sea Level Anomalies sea_surface_height_above_sea_level sla [m] Sea Level Anomalies sea_surface_height_above_sea_level sla_filtered_tpacorr [m] Sea Level Anomalies sea_surface_height_above_sea_level

sla_tpacorr [m] Sea Level Anomalies sea_surface_height_above_sea_level



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GLOBAL_OMI_SL_regional trends

glo

bal_

om

i_sl_

r

eg

ion

al_

tre

nd

s Map of the altimeter regional mean sea level trends in the global ocean. The trends are not corrected for the

GIA effect.

msl_trend [mm/yr] Regional mean sea level trends tendency_of_sea_surface_height_above_sea_level

BALTIC_OMI_SL_area_averaged_anomalies

balt

ic_

om

i_sl_

are

a_

avera

ge

d_

a

no

malies

Altimeter mean sea level daily evolution (filtered and unfiltered) estimated in the Baltic Sea derived from the average of the gridded sea level maps weighted by the cosine of the latitude. The timeseries is low-pass filtered, the annual and semi-annual periodic signals are adjusted. The curves are corrected for the GIA using the ICE5G-VM2 GIA model (Peltier, 2004).

sla_filtered [m] Sea Level Anomalies sea_surface_height_above_sea_level sla [m] Sea Level Anomalies sea_surface_height_above_sea_level

BLKSEA_OMI_SL_area_averaged_anomalies

blk

sea_

om

i_sl_

are

a_avera

ged

_a

no

ma

lie

s

Altimeter mean sea level daily evolution (filtered and unfiltered) estimated in the Black Sea derived from the average of the gridded sea level maps weighted by the cosine of the latitude. The timeseries is low-pass filtered, the annual and semi-annual periodic signals are adjusted. The curves are corrected for the GIA using the ICE5G-VM2 GIA model (Peltier, 2004).


IBI_OMI_SL_area_averaged_anomalies

ibi_

om

i

_sl_

are

a_avera

ged

_a

n

om

alie

s

Altimeter mean sea level daily evolution (filtered and unfiltered) estimated in the Iberian-Biscay-Irish area derived from the average of the gridded sea level maps weighted by the cosine of the latitude. The timeseries is low-pass filtered, the annual and semi-annual periodic signals are adjusted. The curves are corrected for the


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GIA using the ICE5G-VM2 GIA model (Peltier, 2004).


MEDSEA_OMI_SL_area_averaged_anomalies

med

se

a_o

mi_

sl_

are

a_avera

ged

_

an

om

alies

Altimeter mean sea level daily evolution (filtered and unfiltered) estimated in the Mediterranean Sea derived from the average of the gridded sea level maps weighted by the cosine of the latitude. The timeseries is low-pass filtered, the annual and semi-annual periodic signals are adjusted. The curves are corrected for the GIA using the ICE5G-VM2 GIA model (Peltier, 2004).


NORTHWESTSHELF_OMI_SL_area_averaged_anomalies

no

rth

we

sts

helf

_o

mi_

sl_

are

a_av

era

ged

_a

no

mali

es

Altimeter mean sea level daily evolution (filtered and unfiltered) estimated in the European North-West Shelf region derived from the average of the gridded sea level maps weighted by the cosine of the latitude. The timeseries is low-pass filtered, the annual and semi-annual periodic signals are adjusted. The curves are corrected for the GIA using the ICE5G-VM2 GIA model (Peltier, 2004).



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II.3 Product System Description

The CMEMS sea level OMIs are derived from the delayed-time altimeter sea level gridded products generated by the DUACS altimeter production system and distributed by the Copernicus Climate Change Service (C3S) since these products are designed for climate applications. The DUACS altimeter processing sequences can be divided into the following main steps (details are described in Pujol et al., 2016):

Acquisition

Pre-processing homogenization

Input data quality control

Multi-mission cross-calibration

Along-track products generation

Gridded merged products generation

Final quality control

Among them, the multi-mission cross-calibration process ensures that all data flows from all satellites have consistent and accurate information. This allows the reduction of various sources of geographically correlated error patterns and ensures an optimal homogenization of the dataset. Global and regional biases between two successive altimeter missions are reduced and finally, the multi-mission along-track measurements are mapped thanks to an optimal interpolation method on a daily ¼° x ¼° regular grid. Additional information on the data processing can be found in Pujol et al. (2016), Ablain et al. (2017) and Escudier et al. (2017).

II.4 How to download a product

i. Download a product through the CMEMS Web Portal Ftp 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 FTP Service.

http://marine.copernicus.eu/web/34-products-and-services-faq.php#1

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

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


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III FILES NOMENCLATURE AND FORMAT

III.1 Nomenclature of files when downloaded through the CMEMS FTP Services

The CMEMS sea level OMI files nomenclature when downloaded through the CMEMS FTP Services is based on the following nomenclature:

<datasetname>_<timestep>_P<productiontime>_<freetext>

Where :

<datasetname> is the dataset reference.

<timestep> is the first time step in the file.

<productiontime> is the production time when the file was generated.

<freetext> includes potential additional information.

III.2 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.


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III.3 File size

DATASET NAME NAME OF FILE DIMENSION [MB]*

Compressed Uncompressed

global_omi_sl_area_averaged_anomalies

global_omi_sl_area_averaged_anomalies_19930101_Pyyyymmdd.nc

N/A 0.2

global_omi_sl_regional_trends

global_omi_sl_regional_trends_19930101_Pyyyymm

dd.nc N/A 4.0

baltic_omi_sl_area_averaged_anomalies

baltic_omi_sl_area_averaged_anomalies_19930101_

Pyyyymmdd.nc N/A 0.2

blksea_omi_sl_area_averaged_anomalies

blksea_omi_sl_area_averaged_anomalies_19930101

_Pyyyymmdd.nc N/A 0.2

ibi_omi_sl_area_averaged_anomalies

ibi_omi_sl_area_averaged_anomalies_19930101_Py

yyymmdd.nc N/A 0.2

medsea_omi_sl_area_averaged_anomalies

medsea_omi_sl_area_averaged_anomalies_1993010

1_Pyyyymmdd.nc N/A 0.2

northwestshelf_omi_sl_area_averaged_anomalies

northwestshelf_omi_sl_area_averaged_anomalies_19930101_Pyyyymmdd.nc

N/A 0.2

III.4 Reading Softwares

The products are stored using the NetCDF-CF format. Note that these data can be browsed and used through several softwares, like:

Basic Radar Altimetry Toolbox: http://www.altimetry.info ncBrowse: http://www.epic.noaa.gov/java/ncBrowse/

NetCDF Operator (NCO): http://nco.sourceforge.net/

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 REFERENCES

See the Quality Information Document (QUID) CMEMS_OMI_SEALEVEL_QUID.pdf (http://cmems-resources.cls.fr/documents/QUID/CMEMS-OMI-QUID-GLO-SL.pdf).

Pujol, M.-I., Faugere, Y,. Taburet, G., Dupuy, S., Pelloquin, C., Ablain, M., and Picot, N.: DUACS DT2014: the new multi-mission altimeter data set reprocessed over 20 years, Ocean Sci., 12, 1067-1090. doi: 10.5194/os-12-1067-2016, 2016.

Ablain, M., Legeais, J.-F., Prandi, P., Marcos, M., Fenoglio-Marc, L., Dieng, H.-B., Benveniste, J. and Cazenave, A.: Satellite altimetry-based sea level at global and regional scales, Surv Geophys., 38, 7-31. doi: 10.1007/s10712-016-9389-8, 2017.

Escudier, P. A. Couhert, F. Mercier, A. Mallet, P. Thibaut, N. Tran, L. Amarouche, B. Picard, L. Carrère, G. Dibarboure, M. Ablain, J. Richard, N. Steunou, P. Dubois, M. H. Rio, J. Dorandeu (2017) Satellite radar altimetry: principle, geophysical correction and orbit, accuracy and precision, In CRC Book on satellite altimetry, guest editors Stammer, D. and Cazenave, A.



product user manual...altimeter mean sea level daily evolution (filtered and unfiltered) estimated...

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