QUALITY INFORMATION DOCUMENT For Global Ocean QUALITY INFORMATION DOCUMENT For Global Ocean Reanalysis

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  • QUALITY INFORMATION DOCUMENT

    For Global Ocean Reanalysis Multi-model Ensemble Products GREP-V1

    GLOBAL-REANALYSIS-PHY-001-026

    Issue: 1.1

    Contributors: Charles Desportes, Gilles Garric, Charly Régnier, Marie Drévillon, Laurent Parent, Gilles Garric, Yann Drillet, Simona Masina, Andrea Storto, Isabelle Mirouze, Andrea Cipollone, Hao Zuo, Magdalena Balmaseda, Drew Peterson, Richard Wood, Laura Jackson, Sandrine Mulet, Eric Greiner

    Approval Date by Quality Assurance Review Group :

  • Quality Information Document

    For product

    GLOBAL-REANALYSIS-PHY-001-026

    Ref :CMEMS-GLO-QUID-001-026

    Date : Novembre 2017

    Issue : 1.1

    © EU Copernicus Marine Service – Public Page 2/ 40

    CHANGE RECORD

    Issue Date § Description of Change Author Checked

    By

    1.0 3 January 2017

    all First version of document Charles Desportes, Marie Drévillon

    Yann Drillet

    1.1 7 novembre 2017

    add 2016 T&S and velocities validation

    Charles Desportes Yann Drillet

  • Quality Information Document

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    GLOBAL-REANALYSIS-PHY-001-026

    Ref :CMEMS-GLO-QUID-001-026

    Date : Novembre 2017

    Issue : 1.1

    © EU Copernicus Marine Service – Public Page 3/ 40

    TABLE OF CONTENTS

    I EXECUTIVE SUMMARY ............................................................................................................................ 4

    Products covered by this document ........................................................................................................... 4 I.1

    Summary of the results ............................................................................................................................... 4 I.2 Temperature ....................................................................................................................................... 4 I.2.1 Salinity ................................................................................................................................................ 5 I.2.2 Velocities ............................................................................................................................................. 5 I.2.3

    Estimated Accuracy Number ..................................................................................................................... 6 I.3

    II Production Subsystems description ............................................................................................................... 7

    III Validation framework ............................................................................................................................... 8

    IV Validation results of GREP-V1 ................................................................................................................... 10

    Temperature ........................................................................................................................................... 10 IV.1 T-CLASS1-T3D-MEAN .................................................................................................................. 10 IV.1.1 T-CLASS1-SST-MEAN ................................................................................................................... 12 IV.1.2 T-CLASS1-SST-TREND ................................................................................................................. 13 IV.1.3 T-CLASS2-MOORINGS ................................................................................................................. 14 IV.1.4 T-CLASS3-SST_2DMEAN ............................................................................................................. 15 IV.1.5 T-CLASS3-HC_LAYER ................................................................................................................. 15 IV.1.6 T-CLASS3-IC_CHANGE ............................................................................................................... 17 IV.1.7 T-CLASS4-LAYER ......................................................................................................................... 18 IV.1.8 T-STDEV .......................................................................................................................................... 22 IV.1.9

    Salinity ..................................................................................................................................................... 24 IV.2 S-CLASS1-S3D_MEAN .................................................................................................................. 24 IV.2.1 S-CLASS1-SSS-TREND .................................................................................................................. 27 IV.2.2 S-CLASS2-MOORINGS ................................................................................................................. 28 IV.2.3 S-CLASS3-SC_LAYER ................................................................................................................... 29 IV.2.4 S-CLASS3-IC_CHANGE ................................................................................................................ 30 IV.2.5 S-CLASS4-LAYER .......................................................................................................................... 31 IV.2.6 S-STDEV .......................................................................................................................................... 35 IV.2.7

    Currents .................................................................................................................................................. 37 IV.3 UV-CLASS1-15m_MEAN ............................................................................................................... 37 IV.3.1 UV-CLASS2-MKE_1000m ............................................................................................................. 39 IV.3.2

    V references ..................................................................................................................................................... 40

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    I EXECUTIVE SUMMARY

    Products covered by this document I.1

    The products assessed in this document are referenced as: GLOBAL-REANALYSIS-PHY-001-026 for Global Reanalysis Multi-Model Ensemble Product GREP.

    Global ocean reanalyses are homogeneous 3D gridded descriptions of the physical state of the ocean spanning several decades, produced with a numerical ocean model constrained with data assimilation of satellite and in situ observations. The multi-model ensemble approach allows uncertainties or error bars in the ocean state to be estimated. The ensemble mean may even provide, for certain regions and/or periods, a more reliable estimate than any individual reanalysis product.

    Four reanalyses covering the 1993-2016 period during which altimeter altimetry data observations are available; GLORYS2V4 from Mercator Ocean (Fr), ORAS5 from ECMWF, GloSea5 from Met Office (UK), and C-GLORS05 from CMCC (It) provided four different time series of global ocean simulations 3D monthly estimates, which were post-processed to create the new product called GREP (Global Reanalysis Ensemble Product), and for which the following variables are available:

    * sea_water_potential_temperature * sea_water_salinity * eastward_sea_water_velocity * northward_sea_water_velocity

    Other variables like ssh and ice variables will be available in next releases.These reanalyses are built to be as close as possible to the observations (i.e. realistic) and in agreement with the model physics. It covers the “altimetric era” (namely 1

    st of January 1993 until 31 December 2016). The numerical

    products available for users are monthly mean averages describing the ocean from surface to bottom (5900 m).

    The product comprises 12 datasets (6 datasets for temperature, and 6 for salinity), which consist for T and S of 4 global ocean reanalyses datasets, their ensemble mean and standard deviation, on a regular grid at 1° horizontal resolution.

    Summary of the results I.2

    Although all the individual members and the ensemble mean have been assessed independently, this summary only describes the quality of the GREP ensemble mean product. For more details on individual members results, please see the references listed at the end of the document, and section IV of this document.

    Temperature I.2.1

    The GREP-V1 ensemble mean has very small biases (less than 0.1°C on global average) and RMS errors (less than 1°C on global average) in temperature with respect to CMEMS CORA in situ data. The largest biases, RMS errors and disagreement between the four members occur during the 1993- 2002 period, in the deep layers (under 800 m) and in the northern Atlantic and Mediterranean Sea, in the polar oceans, in the Indonesian region, and in the western side of the Pacific warm pool.

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    The heat content of the 0-700 m increases with time during the whole period. Only the deepest layers (below