Satellite altimetry and ocean dynamics

This paper provides a summary of recent results derived from satellite altimetry. It is focused on altimetry and ocean dynamics with synergistic use of other remote sensing techniques, in-situ data and integration aspects through data assimilation. Topics include mean ocean circulation and geoid issues, tropical dynamics and large-scale sea level and ocean circulation variability, high-frequency and intraseasonal variability, Rossby waves and mesoscale variability.This paper provides a summary of recent results derived from satellite altimetry. It is focused on altimetry and ocean dynamics with synergistic use of other remote sensing techniques, in-situ data and integration aspects through data assimilation. Topics include mean ocean circulation and geoid issues, tropical dynamics and large-scale sea level and ocean circulation variability, high-frequency and intraseasonal variability, Rossby waves and mesoscale variability. To cite this article: L.L. Fu, P.-Y. Le Traon, C. R. Geoscience 338 (2006)

Improveing test suites for efficient fault localization

ABSTRACT The need for testing-for-diagnosis strategies has been identified for a long time, but the explicit link from testing to diagnosis (fault localization) is rare. Analyzing the type of information needed for efficient fault localization, we identify the attribute (called Dynamic Basic Block) that restricts the accuracy of a diagnosis algorithm. Based on this attribute, a test-for-diagnosis criterion is proposed and validated through rigorous case studies: it shows that a test suite can be improved to reach a high level of diagnosis accuracy. So, the dilemma between a reduced testing effort (with as few test cases as possible) and the diagnosis accuracy (that needs as much test cases as possible to get more information) is partly solved by selecting test cases that are dedicated to diagnosis

Improveing test suites for efficient fault localization

ABSTRACT The need for testing-for-diagnosis strategies has been identified for a long time, but the explicit link from testing to diagnosis (fault localization) is rare. Analyzing the type of information needed for efficient fault localization, we identify the attribute (called Dynamic Basic Block) that restricts the accuracy of a diagnosis algorithm. Based on this attribute, a test-for-diagnosis criterion is proposed and validated through rigorous case studies: it shows that a test suite can be improved to reach a high level of diagnosis accuracy. So, the dilemma between a reduced testing effort (with as few test cases as possible) and the diagnosis accuracy (that needs as much test cases as possible to get more information) is partly solved by selecting test cases that are dedicated to diagnosis

On the Evolution of Keyword-Driven Test Suites

Many companies rely on software testing to verify that their software products meet their requirements. However, test quality and, in particular, the quality of end-to-end testing is relatively hard to achieve. The problem becomes challenging when software evolves, as end-to-end test suites need to adapt and conform to the evolved software. Unfortunately, end-to-end tests are particularly fragile as any change in the application interface, e.g., application flow, location or name of graphical user interface elements, necessitates a change in the tests. This paper presents an industrial case study on the evolution of Keyword-Driven test suites, also known as Keyword-Driven Testing (KDT). Our aim is to demonstrate the problem of test maintenance, identify the benefits of Keyword-Driven Testing and overall improve the understanding of test code evolution (at the acceptance testing level). This information will support the development of automatic techniques, such as test refactoring and repair, and will motivate future research. To this end, we identify, collect and analyze test code changes across the evolution of industrial KDT test suites for a period of eight months. We show that the problem of test maintenance is largely due to test fragility (most commonly-performed changes are due to locator and synchronization issues) and test clones (over 30% of keywords are duplicated). We also show that the better test design of KDT test suites has the potential for drastically reducing (approximately 70%) the number of test code changes required to support software evolution. To further validate our results, we interview testers from BGL BNP Paribas and report their perceptions on the advantages and challenges of keyword-driven testing

Synthesis of OSSE results

Observing System Simulation Experiments (OSSEs): Report describing the robust results obtained from across the model

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

Eddy dynamics from satellite altimetry

Most of the kinetic energy of ocean circulation is contained in ubiquitous mesoscale eddies. Their prominent signatures in sea surface height have rendered satellite altimetry highly effective in observing global ocean eddies. Our knowledge of ocean eddy dynamics has grown by leaps and bounds since the advent of satellite altimetry in the early 1980s. A satellite’s fast sampling allows a broad view of the global distribution of eddy variability and its spatial structures. Since the early 1990s, the combination of data available from two simultaneous flying altimeters has resulted in a time-series record of global maps of ocean eddies. Despite the moderate resolution, these maps provide an opportunity to study the temporal and spatial variability of the surface signatures of eddies at a level of detail previously unavailable. A global census of eddies has been constructed to assess their population, polarity, intensity, and nonlinearity. The velocity and pattern of eddy propagation, as well as eddy transports of heat and salt, have been mapped globally. For the first time, the cascade of eddy energy through various scales has been computed from observations, providing evidence for the theory of ocean turbulence. Notwithstanding the tremendous progress made using existing observations, their limited resolution has prevented study of variability at wavelengths shorter than 100 km, where important eddy processes take place, ranging from energy dissipation to mixing and transport of water properties that are critical to understanding the ocean’s roles in Earth’s climate. The technology of radar interferometry promises to allow wide-swath measurement of sea surface height at a resolution that will resolve eddy structures down to 10 km. This approach holds the potential to meet the challenge of extending the observations to submesoscales and to set a standard for future altimetric measurement of the ocean

Global observations of fine-scale ocean surface topography with the surface water and ocean topography (SWOT) mission

© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in [citation], doi:[doi]. Morrow, R., Fu, L., Ardhuin, F., Benkiran, M., Chapron, B., Cosme, E., d'Ovidio, F., Farrar, J. T., Gille, S. T., Lapeyre, G., Le Traon, P., Pascual, A., Ponte, A., Qiu, B., Rascle, N., Ubelmann, C., Wang, J., & Zaron, E. D. Global observations of fine-scale ocean surface topography with the surface water and ocean topography (SWOT) mission. Frontiers in Marine Science, 6(232),(2019), doi:10.3389/fmars.2019.00232.The future international Surface Water and Ocean Topography (SWOT) Mission, planned for launch in 2021, will make high-resolution 2D observations of sea-surface height using SAR radar interferometric techniques. SWOT will map the global and coastal oceans up to 77.6∘ latitude every 21 days over a swath of 120 km (20 km nadir gap). Today’s 2D mapped altimeter data can resolve ocean scales of 150 km wavelength whereas the SWOT measurement will extend our 2D observations down to 15–30 km, depending on sea state. SWOT will offer new opportunities to observe the oceanic dynamic processes at scales that are important in the generation and dissipation of kinetic energy in the ocean, and that facilitate the exchange of energy between the ocean interior and the upper layer. The active vertical exchanges linked to these scales have impacts on the local and global budgets of heat and carbon, and on nutrients for biogeochemical cycles. This review paper highlights the issues being addressed by the SWOT science community to understand SWOT’s very precise sea surface height (SSH)/surface pressure observations, and it explores how SWOT data will be combined with other satellite and in situ data and models to better understand the upper ocean 4D circulation (x, y, z, t) over the next decade. SWOT will provide unprecedented 2D ocean SSH observations down to 15–30 km in wavelength, which encompasses the scales of “balanced” geostrophic eddy motions, high-frequency internal tides and internal waves. This presents both a challenge in reconstructing the 4D upper ocean circulation, or in the assimilation of SSH in models, but also an opportunity to have global observations of the 2D structure of these phenomena, and to learn more about their interactions. At these small scales, ocean dynamics evolve rapidly, and combining SWOT 2D SSH data with other satellite or in situ data with different space-time coverage is also a challenge. SWOT’s new technology will be a forerunner for the future altimetric observing system, and so advancing on these issues today will pave the way for our future.The authors were mostly funded through the NASA Physical Oceanography Program and the CNES/TOSCA programs for the SWOT and OSTST Science teams. AnP acknowledges support from the Spanish Research Agency and the European Regional Development Fund (Award No. CTM2016-78607-P). AuP acknowledges support from the ANR EQUINOx (ANR-17-CE01-0006-01)

Global Observations of Fine-Scale Ocean Surface Topography With the Surface Water and Ocean Topography (SWOT) Mission

The future international Surface Water and Ocean Topography (SWOT) Mission, planned for launch in 2021, will make high-resolution 2D observations of sea-surface height using SAR radar interferometric techniques. SWOT will map the global and coastal oceans up to 77.6 latitude every 21 days over a swath of 120 km (20 km nadir gap). Today’s 2D mapped altimeter data can resolve ocean scales of 150 km wavelength whereas the SWOT measurement will extend our 2D observations down to 15–30 km, depending on sea state. SWOT will offer new opportunities to observe the oceanic dynamic processes at scales that are important in the generation and dissipation of kinetic energy in the ocean, and that facilitate the exchange of energy between the ocean interior and the upper layer. The active vertical exchanges linked to these scales have impacts on the local and global budgets of heat and carbon, and on nutrients for biogeochemical cycles. This review paper highlights the issues being addressed by the SWOT science community to understand SWOT’s very precise sea surface height (SSH)/surface pressure observations, and it explores how SWOT data will be combined with other satellite and in situ data and models to better understand the upper ocean 4D circulation (x, y, z, t) over the next decade. SWOT will provide unprecedented 2D ocean SSH observations down to 15–30 km in wavelength, which encompasses the scales of “balanced” geostrophic eddy motions, high-frequency internal tides and internal waves. Frontiers in Marine Science | www.frontiersin.org 1 May 2019 | Volume 6 | Article 232 Morrow et al. SWOT Fine-Scale Global Ocean Topography This presents both a challenge in reconstructing the 4D upper ocean circulation, or in the assimilation of SSH in models, but also an opportunity to have global observations of the 2D structure of these phenomena, and to learn more about their interactions. At these small scales, ocean dynamics evolve rapidly, and combining SWOT 2D SSH data with other satellite or in situ data with different space-time coverage is also a challenge. SWOT’s new technology will be a forerunner for the future altimetric observing system, and so advancing on these issues today will pave the way for our future

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

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