24 research outputs found
Impact study design
Precise design of impact studies carried out in interaction with WP2 and WP
Toward an improved design of the in-situ observing system for ocean reanalysis, analysis and forecasting: design of experiments
This report presents the work plan within the task 1.3 - Observing System Design Studie
Design of the Observing System Simulation Experiments with multi-platform in situ data and impact on fine- scale structures
This report presents the work plan of the Task 2.3: Observing System Simulation Experiments: impact of multi-platform observations for the validation of satellite observation
Assessment of AtlantOS impact
Assessment of the impact of AtlantOS in situ observing system for Copernicus Marine Service and seasonal predictio
Analysis of the OSSEs with multi-platform in situ data and impact on fine-scale structures
This report includes recommendations for the planification of in situ experiments aimed to reconstruct fine-scale ocean currents (~20 km), such as those that will be conducted to validate SWOT satellite observations
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Intercomparison and validation of the mixed layer depth fields of global ocean syntheses
Intercomparison and evaluation of the global ocean surface mixed layer depth (MLD) fields estimated from a suite of major ocean syntheses are conducted. Compared with the reference MLDs calculated from individual profiles, MLDs calculated from monthly mean and gridded profiles show negative biases of 10â20 m in early spring related to the re-stratification process of relatively deep mixed layers. Vertical resolution of profiles also influences the MLD estimation. MLDs are underestimated by approximately 5â7 (14â16) m with the vertical resolution of 25 (50) m when the criterion of potential density exceeding the 10-m value by 0.03 kg mâ3 is used for the MLD estimation. Using the larger criterion (0.125 kg mâ3) generally reduces the underestimations. In addition, positive biases greater than 100 m are found in wintertime subpolar regions when MLD criteria based on temperature are used. Biases of the reanalyses are due to both model errors and errors related to differences between the assimilation methods. The result shows that these errors are partially cancelled out through the ensemble averaging. Moreover, the bias in the ensemble mean field of the reanalyses is smaller than in the observation-only analyses. This is largely attributed to comparably higher resolutions of the reanalyses. The robust reproduction of both the seasonal cycle and interannual variability by the ensemble mean of the reanalyses indicates a great potential of the ensemble mean MLD field for investigating and monitoring upper ocean processes
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Interannual-decadal variability of wintertime mixed layer depths in the North Pacific detected by an ensemble of ocean syntheses
The interannual-decadal variability of the wintertime mixed layer depths (MLDs) over the North Pacific is investigated from an empirical orthogonal function (EOF) analysis of an ensemble of global ocean reanalyses. The first leading EOF mode represents the interannual MLD anomalies centered in the eastern part of the central mode water formation region in phase opposition with those in the eastern subtropics and the central Alaskan Gyre. This first EOF mode is highly correlated with the Pacific decadal oscillation index on both the interannual and decadal time scales. The second leading EOF mode represents the MLD variability in the subtropical mode water (STMW) formation region and has a good correlation with the wintertime West Pacific (WP) index with time lag of 3 years, suggesting the importance of the oceanic dynamical response to the change in the surface wind field associated with the meridional shifts of the Aleutian Low. The above MLD variabilities are in basic agreement with previous observational and modeling findings. Moreover the reanalysis ensemble provides uncertainty estimates. The interannual MLD anomalies in the first and second EOF modes are consistently represented by the individual reanalyses and the amplitudes of the variabilities generally exceed the ensemble spread of the reanalyses. Besides, the resulting MLD variability indices, spanning the 1948â2012 period, should be helpful for characterizing the North Pacific climate variability. In particular, a 6-year oscillation including the WP teleconnection pattern in the atmosphere and the oceanic MLD variability in the STMW formation region is first detected
New 3-dimensionl biogeochemical products derived from machine learning-based methods
International audienc
On the mesoscale monitoring capability of Argo floats in the Mediterranean Sea
In this work a simplified observing system simulation
experiment (OSSE) approach is used to investigate
which Argo design sampling in the Mediterranean Sea would
be necessary to properly capture the mesoscale dynamics in
this basin. The monitoring of the mesoscale features is not
an initial objective of the Argo network. However, it is an
interesting question from the perspective of future network
extensions in order to improve the ocean state estimates. The
true field used to conduct the OSSEs is provided by a specific
altimetry-gridded merged product for the Mediterranean
Sea. Synthetic observations were obtained by sub-sampling
this âNature Runâ according to different configurations of the
ARGO network. The observation errors required to perform
the OSSEs were obtained through the comparison of sea
level anomalies (SLAs) from altimetry and dynamic height
anomalies (DHAs) computed from the real in situ Argo network.
This analysis also contributes to validate satellite SLAs
with an increased confidence. 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.
Increasing the spatial resolution to nearly 75 km75 km, allows
the capture of most of the mesoscale signal in the basin
and to retrieve the SLA field with a RMSE of 3 cm for spatial
scales larger than 150 km, similar to those presently captured
by the altimetry. This would represent a theoretical reduction
of 40% of the actual RMSE. Such a high-resolution Argo
array composed of around 450 floats, cycling every 10 days,
is expected to increase the actual network cost by approximately
a factor of 6.The research leading these results has
received funding from the European FP7 under the E-AIMS
(Euro-Argo Improvements for the GMES Marine Service) project
(code: 312642) and the Sea Level Thematic Assembly Center (SLTAC)
of the Copernicus Marine and Environment Monitoring
Service (CMEMS).Peer Reviewe