Coastal sea level anomalies and associated trends from Jason satellite altimetry over 2002–2018

Climate-related sea level changes in the world coastal zones result from the superposition of the global mean rise due to ocean warming and land ice melt, regional changes caused by non-uniform ocean thermal expansion and salinity changes, and by the solid Earth response to current water mass redistribution and associated gravity change, plus small-scale coastal processes (e.g., shelf currents, wind & waves changes, fresh water input from rivers, etc.). So far, satellite altimetry has provided global gridded sea level time series up to 10–15 km to the coast only, preventing estimation of sea level changes very close to the coast. Here we present a 16-year-long (June 2002 to May 2018), high-resolution (20-Hz), along-track sea level dataset at monthly interval, together with associated sea level trends, at 429 coastal sites in six regions (Northeast Atlantic, Mediterranean Sea, Western Africa, North Indian Ocean, Southeast Asia and Australia). This new coastal sea level product is based on complete reprocessing of raw radar altimetry waveforms from the Jason-1, Jason-2 and Jason-3 missions

A new phase in the production of quality-controlled sea level data

Sea level is an essential climate variable (ECV) that has a direct effect on many people through inundations of coastal areas, and it is also a clear indicator of climate changes due to external forcing factors and internal climate variability. Regional patterns of sea level change inform us on ocean circulation variations in response to natural climate modes such as El Niño and the Pacific Decadal Oscillation, and anthropogenic forcing. Comparing numerical climate models to a consistent set of observations enables us to assess the performance of these models and help us to understand and predict these phenomena, and thereby alleviate some of the environmental conditions associated with them. All such studies rely on the existence of long-term consistent high-accuracy datasets of sea level. The Climate Change Initiative (CCI) of the European Space Agency was established in 2010 to provide improved time series of some ECVs, including sea level, with the purpose of providing such data openly to all to enable the widest possible utilisation of such data. Now in its second phase, the Sea Level CCI project (SL_cci) merges data from nine different altimeter missions in a clear, consistent and well-documented manner, selecting the most appropriate satellite orbits and geophysical corrections in order to further reduce the error budget. This paper summarises the corrections required, the provenance of corrections and the evaluation of options that have been adopted for the recently released v2.0 dataset (https://doi.org/10.5270/esa-sea_level_cci-1993_2015-v_2.0-201612). This information enables scientists and other users to clearly understand which corrections have been applied and their effects on the sea level dataset. The overall result of these changes is that the rate of rise of global mean sea level (GMSL) still equates to ∼ 3.2 mm yr−1 during 1992–2015, but there is now greater confidence in this result as the errors associated with several of the corrections have been reduced. Compared with v1.1 of the SL_cci dataset, the new rate of change is 0.2 mm yr−1 less during 1993 to 2001 and 0.2 mm yr−1 higher during 2002 to 2014. Application of new correction models brought a reduction of altimeter crossover variances for most corrections

Sea level along the world’s coastlines can be measured by a network of virtual altimetry stations

For nearly 30 years, space-based radar altimetry has been routinely measuring changes in sea level at global and regional scales. But this technique designed for the open ocean does not provide reliable sea level data within 20 km to the coast, mostly due to land contamination within the radar echo in the vicinity of the coast. This problem can now be overcome through dedicated reprocessing, allowing the retrieval of valid sea level data in the 0-20 km band from the coast, and then the access to novel information on sea level change in the world coastal zones. Here we present sea level anomalies and associated coastal sea level trends at 756 altimetry-based virtual coastal stations located along the coasts of North and South America, Northeast Atlantic, Mediterranean Sea, Africa, North Indian Ocean, Asia and Australia. This new dataset, derived from the reprocessing of high-resolution (300 m) along-track altimetry data from the Jason-1, 2 and 3 missions from January 2002 to December 2019, allows the analysis of the decadal evolution of coastal sea level and fills the coastal gap where sparse sea level information is currently available

The dynamical control of subduction parameters on surface topography

he long-wavelength surface deflection of Earth's outermost rocky shell is mainly controlled by large-scale dynamic processes like isostasy or mantle flow. The largest topographic amplitudes are therefore observed at plate boundaries due to the presence of large thermal heterogeneities and strong tectonic forces. Distinct vertical surface deflections are particularly apparent at convergent plate boundaries mostly due to the convergence and asymmetric sinking of the plates. Having a mantle convection model with a free surface that is able to reproduce both realistic single-sided subduction and long-wavelength surface topography self-consistently, we are now able to better investigate this interaction. We separate the topographic signal into distinct features and quantify the individual topographic contribution of several controlling subduction parameters. Results are diagnosed by splitting the topographic signal into isostatic and residual components, and by considering various physical aspects like viscous dissipation during plate bending. Performing several systematic suites of experiments, we are then able to quantify the topographic impact of the buoyancy, rheology, and geometry of the subduction-zone system to each and every topographic feature at a subduction zone and to provide corresponding scaling laws. We identify slab dip and, slightly less importantly, slab buoyancy as the major agents controlling surface topography at subduction zones on Earth. Only the island-arc high and the back-arc depression extent are mainly controlled by plate strength. Overall, his modeling study sets the basis to better constrain deep-seated mantle structures and their physical properties via the observed surface topography on present-day Earth and back through time

Altimetry for the future: Building on 25 years of progress

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the ‘‘Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

Altimetry for the future: building on 25 years of progress

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the “Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

Effets neuroprotecteurs des gaz xénon, protoxyde d'azote et hélium (application à l'accident vasculaire cérébral de type ischémique)

CAEN-BU Médecine pharmacie (141182102) / SudocLYON1-BU Santé (693882101) / SudocSudocFranceF

Mini-vis : l’orthodontie de demain

Les mini-vis d’ancrage font aujourd’hui partie intégrante de l’arsenal thérapeutique de l’orthodontiste. Après de nombreuses recherches expérimentales et cliniques depuis plus de dix ans maintenant, elles répondent parfaitement au cahier des charges de l’orthodontiste et ainsi aux exigences de facilité d’usage, de fiabilité et d’innocuité. Elles satisfont les besoins d’ancrage dans toutes les situations cliniques quelle que soit la typologie du patient ou son passé dentaire, s’intégrant alors dans les plans de traitement pluridisciplinaires. Elles permettent au praticien de garder le contrôle de la biomécanique déjouant enfin les affres du manque de coopération du patient. La biomécanique orthodontique est désormais au service des objectifs occlusaux, fonctionnels et esthétiques

High-resolution surveys of internal tidal waves in Monterey Bay, California, using an autonomous underwater vehicle

The article of record as published may be located at http://dx.doi.org/10.4319/lom.2011.9.571Temperature measured at the Monterey Inner Shelf Observatory (MISO) in southern Monterey Bay reveals frequent solitons and semidiurnal internal tidal bores (ITBs). A field study was undertaken to determine whether these features originate offshore and propagate shoreward over the continental shelf, and to characterize their evolution as they propagate. We developed a new survey method of using an autonomous underwater vehicle (AUV) to tightly track the thermocline along a 4.5 km transect, repeated 18 times over 18 hours, thereby measuring the internal-wave induced isotherm displacement at very high resolution. AUV measurements were compared with measurements at MISO, which is closer to shore. Internal waves of various scales were captured. An ITB of amplitude greater than 20 m propagating shoreward from the outer bay was the dominant feature. Rapid changes in stratification, possibly due to horizontal advection, were also observed. Technical challenges, advantages, and future improvements of this new AUV survey method are discussed. This study demonstrates that AUVs are efficient tools for surveying internal tidal waves