Semi-empirical dissipation source functions for ocean waves: Part I, definition, calibration and validation

New parameterizations for the spectra dissipation of wind-generated waves are proposed. The rates of dissipation have no predetermined spectral shapes and are functions of the wave spectrum and wind speed and direction, in a way consistent with observation of wave breaking and swell dissipation properties. Namely, the swell dissipation is nonlinear and proportional to the swell steepness, and dissipation due to wave breaking is non-zero only when a non-dimensional spectrum exceeds the threshold at which waves are observed to start breaking. An additional source of short wave dissipation due to long wave breaking is introduced to represent the dissipation of short waves due to longer breaking waves. Several degrees of freedom are introduced in the wave breaking and the wind-wave generation term of Janssen (J. Phys. Oceanogr. 1991). These parameterizations are combined and calibrated with the Discrete Interaction Approximation of Hasselmann et al. (J. Phys. Oceangr. 1985) for the nonlinear interactions. Parameters are adjusted to reproduce observed shapes of directional wave spectra, and the variability of spectral moments with wind speed and wave height. The wave energy balance is verified in a wide range of conditions and scales, from gentle swells to major hurricanes, from the global ocean to coastal settings. Wave height, peak and mean periods, and spectral data are validated using in situ and remote sensing data. Some systematic defects are still present, but the parameterizations yield the best overall results to date. Perspectives for further improvement are also given.Comment: revised version for Journal of Physical Oceanograph

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

Pour une histoire du sport et de la jeunesse

Les sports et la jeunesse ont contribué à structurer, selon des principes et des modalités souvent communs, parfois différents ou décalés dans le temps, et avec des fortunes diverses, l'image de l'Allemagne moderne et contemporaine. Ce volume en analyse quelques aspects et tente de clarifier leurs enjeux, les composantes politiques et sociales de leur structuration et les traces de leur influence, jetant ainsi les bases pour des recherches futures

François Reitel, L'Allemagne -Espaces, économie et société. (Nathan, 1996)

Tournadre Jean-François. François Reitel, L'Allemagne -Espaces, économie et société. (Nathan, 1996). In: Recherches Internationales, n°46, 1996. pp. 124-125

Laurent Carroué et Bruno Odent. Allemagne : état d'alerte ? (L’Harmattan, 1994)

Tournadre Jean François. Laurent Carroué et Bruno Odent. Allemagne : état d'alerte ? (L’Harmattan, 1994). In: Recherches Internationales, n°41-42, 1995. pp. 235-236

Karl Marx, lecteur d’Eugène Sue

La Sainte Famille, rédigée en 1844, paraît en février 1845. Cet ouvrage, qui, à l’origine, ne devait pas dépasser les dimensions d’une brochure, est intéressant à plus d’un titre. Tout d’abord, il est le premier qui soit dû à la collaboration de Marx et Engels. En second lieu, il marque une étape dans l’évolution de la pensée de ces deux auteurs, qui se séparent à ce moment‑là de manière décisive des Jeunes Hégéliens dont ils avaient été pendant quelques années très proches. Le titre initiale..

L’influence des pays de l’Est sur les changements en rda

Les changements intervenus en RDA depuis la fin de l’été 1989 se situent au milieu d’une période qui a été marquée des bouleversements qui ont atteint la quasi-totalité des pays de l’Est, à l’exception peut-être de l’Albanie. Avant le mouvement qui a entraîné l’éviction de Honecker, l’Union Soviétique avait entamé une modification radicale, mais progressive, de sa conduite politique à l’initiative de M. Gorbatchev. Dans des conditions différentes, et plus récemment, la Pologne et la Hongrie a..

Avant‑Propos

Les textes ici rassemblés correspondent pour l'essentiel aux contributions prononcées lors d'une journée d'études organisée par Gilbert Krebs et moi‑même le 31 mai 2002, à l'UFR d'allemand de la Sorbonne Nouvelle (Paris III). L'idée nous en est venue à partir d'un double constat. D'une part, en France tout au moins, la recherche sur la fonction historique, sociétale, culturelle et idéologique de la jeunesse et du sport n'a commencé à se développer que récemment, alors que le discours sur la j..

L’image de la RDA dans L’Humanité et dans Le Monde de 1969 à 1989

Les convenances académiques et l’honnêteté scientifique commandent d’abord de justifier la limitation du corpus. Il aurait été possible d’élargir le champ de l’investigation à la radio et à la télévision françaises, mais, outre que cela n’aurait pas considérablement ouvert l’éventail des représentations proposées, le risque aurait été de se limiter à la constatation de l’itération de poncifs au demeurant facilement interprétables, comme par exemple les images de militaires de la RDA défilant ..