S. Guinehut

Collecte Localisation Satellites (France)

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Pierre‐Yves Le Traon

Ifremer

Sandrine Mulet

Collecte Localisation Satellites (France)

G. Larnicol

Collecte Localisation Satellites (France)

Ananda Pascual

Mediterranean Institute for Advanced Studies

Bruno Buongiorno Nardelli

Institute of Marine Science

Nicolas Ferry

Nantes Université

Andrea Storto

Institute of Marine Science

Magdalena Balmaseda

European Centre for Medium-Range Weather Forecasts

Matthew Martin

Met Office

Simón Ruíz

Mediterranean Institute for Advanced Studies

Cooperative Institutions

Centre National de la Recherche Scientifique

Mercator Ocean (France)

Institut de Recherche pour le Développement

Laboratoire d’Études en Géophysique et Océanographie Spatiales

Ifremer

Collecte Localisation Satellites (France)

Met Office

Scripps Institution of Oceanography

Université de Bretagne Occidentale

National Oceanic and Atmospheric Administration

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Southern Ocean Mixed‐Layer Seasonal and Interannual Variations From Combined Satellite and In Situ Data

Journal of Geophysical Research Oceans (2017)

Bruno Buongiorno Nardelli S. Guinehut Nathalie Verbrugge Yuri Cotroneo Enrico Zambianchi

Abstract The depth of the upper ocean mixed layer provides fundamental information on the amount of seawater that directly interacts with the atmosphere. Its space‐time variability modulates water mass formation and carbon sequestration processes related to both the physical and biological pumps. These processes are particularly relevant in the Southern Ocean, where surface mixed‐layer depth estimates are generally obtained either as climatological fields derived from in situ observations or through numerical simulations. Here we demonstrate that weekly observation‐based reconstructions can be used to describe the variations of the mixed‐layer depth in the upper ocean over a range of space and time scales. We compare and validate four different products obtained by combining satellite measurements of the sea surface temperature, salinity, and dynamic topography and in situ Argo profiles. We also compute an ensemble mean and use the corresponding spread to estimate mixed‐layer depth uncertainties and to identify the more reliable products. The analysis points out the advantage of synergistic approaches that include in input the sea surface salinity observations obtained through a multivariate optimal interpolation. Corresponding data allow to assess mixed‐layer depth seasonal and interannual variability. Specifically, the maximum correlations between mixed‐layer anomalies and the Southern Annular Mode are found at different time lags, related to distinct summer/winter responses in the Antarctic Intermediate Water and Sub‐Antarctic Mode Waters main formation areas.

Mixed layer

Argo

Temperature salinity diagrams

Mode (computer interface)

Surface layer

10.1002/2017jc013314

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Citations (58)

On the mesoscale monitoring capability of Argo floats in the Mediterranean Sea

Antonio Sánchez‐Román Simón Ruíz Ananda Pascual Baptiste Mourre S. Guinehut

Abstract. In this work an Observing System Simulation Experiment (OSSE) approach is used to investigate the Argo array spatial sampling necessary in the Mediterranean Sea to recover the mesoscale signal as seen by altimetry. The monitoring of the mesoscale features is not an initial objective of the Argo network. However, it is an interesting question in the perspective of future network extensions in order to improve the ocean state estimates. A quality assessment of the performances of the altimeter product is carried out to quantify the differences between Argo and altimetry needed to conduct the simulation experiments. The method used here to evaluate the altimeter data is based on the comparison of Sea Level Anomalies (SLA) from altimetry and Dynamic Height Anomalies (DHA) referred to both 400 and 900 dbar computed from the in-situ Argo network. A standard deviation of the differences between SLA and DHA of 4.92 cm is obtained when comparing altimetry and Argo data referred to 400 dbar. The simulation experiments show that a configuration similar to the current Argo array in the Mediterranean (with a spatial resolution of 2° × 2°) is only able to recover the large-scale signals of the basin. On the contrary, the SLA field reconstructed from a 0.75° x 0.75° Argo network can retrieve most of the mesoscale signal. Such an Argo array of around 450 floats in the Mediterranean Sea would be enough to recover the SLA field with an RMSE of 3 cm for spatial scales higher than 150 km, similar to those captured by the altimetry.

Argo

10.5194/os-2016-77

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Citations (2)

A new assessment of the error budget of global mean sea level rate estimated by satellite altimetry over 1993–2008

Ocean science (2009)

Michaël Ablain Anny Cazenave G. Valladeau S. Guinehut

Abstract. A new error budget assessment of the global Mean Sea Level (MSL) determined by TOPEX/Poseidon and Jason-1 altimeter satellites between January 1993 and June 2008 is presented using last altimeter standards. We discuss all potential errors affecting the calculation of the global MSL rate. We also compare altimetry-based sea level with tide gauge measurements over the altimetric period. Applying a statistical approach, this allows us to provide a realistic error budget of the MSL rise measured by satellite altimetry. These new calculations highlight a reduction in the rate of sea level rise since 2005, by ~2 mm/yr. This represents a 60% reduction compared to the 3.3 mm/yr sea level rise (glacial isostatic adjustment correction applied) measured between 1993 and 2005. Since November 2005, MSL is accurately measured by a single satellite, Jason-1. However the error analysis performed here indicates that the recent reduction in MSL rate is real.

Tide gauge

Post-glacial rebound

Satellite Altimetry

10.5194/os-5-193-2009

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Citations (245)

Data Quality Assessment of In Situ and Altimeter Observations Through Two-Way Intercomparison Methods

ESASP (2013)

S. Guinehut G. Valladeau Jean‐François Legeais Marie‐Hélène Rio Michaël Ablain

Quality Assessment

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NEW GLOBAL VERTICAL DISTRIBUTION OF GRIDDED PARTICULATE ORGANIC CARBON AND CHLOROPHYLL-A CONCENTRATION USING MACHINE LEARNING FOR CMEMS

HAL (Le Centre pour la Communication Scientifique Directe) (2021)

Raphaëlle Sauzède Hervé Claustre Remanan Pannimpullath Julia Uitz S. Guinehut

Particulate organic carbon

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Estimating global 3D ageostrophic motion at the mesoscale: operational perspectives and future challenges

EGU General Assembly Conference Abstracts (2019)

Bruno Buongiorno Nardelli S. Guinehut Sandrine Mulet Daniele Iudicone

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Sea level budget over 2003–2008: A reevaluation from GRACE space gravimetry, satellite altimetry and Argo

Global and Planetary Change (2008)

Anny Cazenave K. Dominh S. Guinehut Étienne Berthier William Llovel

Argo

Future sea level

Gravimetry

10.1016/j.gloplacha.2008.10.004

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Citations (300)

Argo Data 1999–2019: Two Million Temperature-Salinity Profiles and Subsurface Velocity Observations From a Global Array of Profiling Floats

Frontiers in Marine Science (2020)

Annie P. S. Wong Susan Wijffels Stephen C. Riser Sylvie Pouliquen Shigeki Hosoda

In the past two decades, the Argo Program has collected, processed and distributed over two million vertical profiles of temperature and salinity from the upper two kilometers of the global ocean. A similar number of subsurface velocity observations near 1000 dbar have also been collected. This paper recounts the history of the global Argo Program, from its aspiration arising out of the World Ocean Circulation Experiment, to the development and implementation of its instrumentation and telecommunication systems, and the various technical problems encountered. We describe the Argo data system and its quality control procedures, and the gradual changes in the vertical resolution and spatial coverage of Argo data from 1999 to 2019. The accuracies of the float data have been assessed by comparison with high-quality shipboard measurements, and are concluded to be 0.002°C for temperature, 2.4 dbar for pressure, and 0.01 PSS-78 for salinity, after delayed-mode adjustments. Finally, the challenges faced by the vision of an expanding Argo Program beyond 2020 are discussed.

Argo

Temperature salinity diagrams

Instrumentation

Ocean observations

10.3389/fmars.2020.00700

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Citations (265)

DATA ASSEMBLY AND PROCESSING FOR OPERATIONAL OCEANOGRAPHY: TEN YEARS OF ACHIEVEMENTS

Oceanography (2009)

Pierre‐Yves Le Traon Gilles Larnicol S. Guinehut Sylvie Pouliquen Abderrahim Bentamy

Data assembly and processing centers are essential elements of the operational oceanography infrastructure. They provide data and products needed by modeling and data assimilation systems; they also provide products directly usable for applications. This paper discusses the role and functions of the data centers for operational oceanography. It describes some of the main data assembly centers (Argo and in situ data, altimetry, sea surface temperature) developed during the Global Ocean Data Assimilation Experiment. An overview of other data centers (wind and fluxes, ocean color, sea ice) is also given. Much progress has been achieved over the past 10 years to validate, intercalibrate, and merge altimeter data from multiple satellites. Accuracy and timeliness of products have been improved, and new products have been developed. The same is true for sea surface temperature data through the Global High-Resolution Sea Surface Temperature Pilot Project. A breakthrough in processing, quality control, and assembly for in situ data has also been achieved through the development of the real-time and delayed-mode Argo data system. In situ and remote-sensing data are now systematically and jointly used to calibrate, validate, and monitor over the long term the quality and consistency of the global ocean observing system. Main results are illustrated. There is also a review of the development and use of products that merge in situ and remote-sensing data. Future issues and main prospects are discussed in the conclusion.

10.5670/oceanog.2009.66

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Citations (20)

A global comparison of Argo and satellite altimetry observations

Anne-Lise Dhomps S. Guinehut Pierre‐Yves Le Traon G. Larnicol

Abstract. Differences and complementarities between Sea Level Anomalies (SLA) deduced from altimeter measurements and dynamic height anomalies (DHA) calculated from Argo in situ temperature (T) and salinity (S) profiles are globally analyzed. Compared to previous studies, Argo data allows a much better spatial coverage of all oceans and particularly the Southern Ocean, the use of salinity measurements and the use of a deeper reference level. The use of time series along the Argo float trajectories also provides a means to describe the vertical structure of the ocean both for the low frequency and the mesoscale part of the circulation. The comparison shows the very good consistency between Argo and altimeter observations. Correlations range from 0.9 in low latitudes to 0.3 in high latitudes where the contributions of deep baroclinic and barotropic signals are the largest. The study underlines the large influence of salinity observations on the consistency between altimetry and hydrographic observations. SLA/DHA consistency is thus improved by 35% (relative to the SLA minus DHA signal) by using measured S profiles instead of climatology data. The use of a deep reference level also significantly improves the correlation at mid and high latitudes. The role of seasonal signals on the correlation and regression analysis between altimeter and Argo observations is also analyzed. As they are mainly associated with the heating/cooling of surface layers, removing these large scale signals significantly reduces the correlation and impacts the geographical structure of the Argo/altimetry regression coefficients. These results emphasize the need to separate the different time and space scales in order to improve the merging of the two data sets. The study of seasonal to interannual SLA minus DHA signals finally reveals interesting signals related to deep ocean circulation variations. Future work is, however, needed to understand the observed differences and relate them to different forcing mechanisms.

Argo

Temperature salinity diagrams

Dynamic height

10.5194/osd-7-995-2010

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Citations (3)