Title

[OLD TEMPLATE] Ocean heat content (OHC) and earth energy imbalance (EEI)

Date (Publication)

2020-12-15

Abstract

The Ocean Heat Content ("OHC") is estimated from the measurement of the thermal expansion of the ocean based on differences between the total sea-level content derived from altimetry measurements and the mass content derived from gravimetry data, noted “altimetry-gravimetry”.

The Earth Energy Imbalance ("EEI") indicator is derived from the temporal variations of the ocean heat content, i.e. by calculating its derivative (called the ocean heat uptake).

The product is delivered in two distinct files. The main one contains the essential variables like Global Ocean Heat Content, Earth Energy Imbalance time series and their relative variance-covariance matrices. The second file contains more variables than the first product like time series of Ocean Mass, Sea Level et Steric Sea Level change grids. It also includes additional variables that were not used for the Global ocean heat content calculation, such as the Global mean of ocean mass, Global mean sea level and Global mean steric sea level time series, but which may nevertheless be of interest to users.

Users will therefore be able to find, among other things :

- the regional map of the Ocean Heat Content trends (see image associated with this metadata sheet),

- global ocean heat content change time series (representative of the globe within the extent of data availability),

- earth energy imbalance time series (from global OHC filtered-out from signals lower than 3 years),

- the uncertainties associated with these two datasets.

Credit

ESA/CNES/LEGOS/Magellium projet MOHeaCAN

Point of contact

Organisation name	Individual name	Electronic mail address	Role
CNES	AVISO+	aviso@altimetry.fr	Dissemination Unit
Magellium	Florence Marti	florence.marti@magellium.fr	Local service desk
CNES	Benoît Meyssignac	benoit.meyssignac@legos.obs-mip.fr	Principal investigator
AVISO+			Publisher

Centre de données ODATIS

• CDS-SAT-AVISO

Type de jeux de donnée ODATIS

• Aggregate data

Thèmatiques ODATIS

• Added-value products

• Remote sensing

ODATIS aggregation parameters and Essential Variable names

• Ocean heat content

Use limitation

CC-BY (Creative Commons - Attribution)

Access constraints

Other restrictions

Use constraints

Other restrictions

Other legal constraints

When using the MOHeaCAN OHC/EEI dataset in a publication or study, it should be cited using this DOI reference: 10.24400/527896/a01-2020.003 (with version number). The initial version has been supported by ESA in the framework of the MOHeaCAN project (Monitoring Ocean Heat Content and Earth Energy ImbalANce from Space): eo4society.esa.int/projects/moheacan/. Since the version 2.1 (2021/10), CNES supports the dissemination of the products through ODATIS, and for the future evolutions of this product.

Spatial representation type

Grid

Language

Français

Character set

UTF8

Topic category

• Oceans

Begin date

1993-01-01T00:00:00

End date

2022-05-31

Unique resource identifier

EPSG:84

Geometric object type

Composite

Distribution format

Name	Version
NetCDF

OnLine resource

Protocol	Linkage	Name
WWW:LINK	https://www.aviso.altimetry.fr/fr/donnees/produits/produits-indicateurs-oceaniques/contenu-en-chaleur-de-locean-et-desequilibre-energetique-de-la-terre.html	Further information on AVISO+
WWW:DOWNLOAD-1.0-link--download	https://data.aviso.altimetry.fr/aviso-gateway/data/indicators/OHC_EEI/global_OHC_EEI/	Data access through HTTPS
WWW:LINK-1.0-http--metadata-URL	https://doi.org/10.24400/527896/a01-2020.003	DOI
WWW:LINK	https://www.aviso.altimetry.fr/fileadmin/documents/data/tools/OHC-EEI/GIECCO-DT-068-MAG_PUM_V1.8.pdf	User Manual
WWW:DOWNLOAD-1.0-link--download	https://dataterra:odatis@tds-odatis.aviso.altimetry.fr/thredds/catalog/ocean-heat-content-earth-energy-imbalance/global_OHC_EEI/catalog.html	TDS fileserver ODATIS AVISO OHC/EEI

Hierarchy level

Dataset

Statement

The OHC change can be estimated directly from net ocean surface heat fluxes measured based on CERES space measurements, from in situ data observed by the ARGO floats or from ocean model reanalyses. We estimate here the OHC change from an alternative method based on spatial altimetry and gravimetry observations which complements these other approaches and which is very promising to reduce uncertainty estimates.

The OHC is estimated from the measurement of the thermal expansion of the ocean based on differences between the total sea-level content derived from altimetry measurements and the mass content derived from gravimetry data, noted “altimetry-gravimetry”.

This space geodetic approach provides consistent spatial and temporal sampling of the ocean. It samples nearly the entire global oceans, except in polar regions where the sea is completely covered by sea ice (i.e. essentially north of 80°N), and it provides estimates of the OHC variations over the ocean’s entire depth.

The EEI indicator is derived from the temporal variations of the ocean heat content, i.e. by calculating its derivative (called the ocean heat uptake). Energy uptakes from the land, cryosphere and atmosphere reservoirs represent about 10% of the EEI and are taken into account The average value of the EEI is +0.83 W.m-2 with an error of +/- 0.16 W.m-2 (within a 90 % confidence level) and shows that on average the Earth stores energy. This EEI value represents an enormous amount of energy when it is integrated into the entire Earth's surface at the top of the atmosphere (20 km) since the EEI represents a total energy uptake of the Earth of about 400 TW (i.e. about 1000 times the power of the world's nuclear power plant).

References

Ablain et al., OSTST 2022: Monitoring the Ocean Heat Content change and the Earth Energy Imbalance from Space Altimetry and Gravimetry missions

Ablain, M., Meyssignac, B., Zawadzki, L., Jugier, R., Ribes, A., Spada, G., Benveniste, J., Cazenave, A. and Picot, N. (2019) Uncertainty in satellite estimates of global mean sea-level changes, trend and acceleration, Earth Syst. Sci. Data, 11(3), 1189–1202, doi:10.5194/essd-11-1189-2019, 2019.

Blazquez, A., Meyssignac, B., Lemoine, J., Berthier, E., Ribes, A. and Cazenave, A. (2018) Exploring the uncertainty in GRACE estimates of the mass redistributions at the Earth surface: implications for the global water and sea level budgets, Geophys. J. Int., 215(1), 415–430, doi:10.1093/gji/ggy293, 2018.

Marti, F., Blazquez, A., Meyssignac, B., Ablain, M., Barnoud, A., Fraudeau, R., Jugier, R., Chenal, J., Larnicol, G., Pfeffer, J., Restano, M., and Benveniste, J.: Monitoring the ocean heat content change and the Earth energy imbalance from space altimetry and space gravimetry, Earth Syst. Sci. Data Discuss., 1–32, doi: 10.5194/essd-2021-220, 2021.

Meyssignac, B., Boyer, T., Zhao, Z., Hakuba, M. Z., Landerer, F. W., Stammer, D., Köhl, A., Kato, S., L’Ecuyer, T., Ablain, M., Abraham, J. P., Blazquez, A., Cazenave, A., Church, J. A., Cowley, R., Cheng, L., Domingues, C. M., Giglio, D., Gouretski, V., Ishii, M., Johnson, G. C., Killick, R. E., Legler, D., Llovel, W., Lyman, J., Palmer, M. D., Piotrowicz, S., Purkey, S. G., Roemmich, D., Roca, R., Savita, A., Schuckmann, K. von, Speich, S., Stephens, G., Wang, G., Wijffels, S. E., Zilberman, N. (2019) Measuring Global Ocean Heat Content to Estimate the Earth Energy Imbalance, Front. Mar. Sci., 6, doi:10.3389/fmars.2019.00432, 2019.

Metadata

File identifier

72463f1c-eb8b-4892-a13b-540b2bcc8338

Metadata language

Français

Other language

Language	Character encoding
English	UTF8

Character set

UTF8

Hierarchy level

Dataset

Date stamp

2024-08-02T09:15:53.451Z

Metadata standard name

ISO 19115:2003/19139 - SEXTANT

Metadata standard version

1.0