36 research outputs found
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 ââGreenâ 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. Instrumentsâ development and satellite missionsâ 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 25âŻyears 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 âGreenâ 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. Instrumentsâ development and satellite missionsâ 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 CarrouĂ© et Bruno Odent. Allemagne : Ă©tat d'alerte ? (LâHarmattan, 1994)
Tournadre Jean François. Laurent CarrouĂ© et Bruno Odent. Allemagne : Ă©tat d'alerte ? (LâHarmattan, 1994). In: Recherches Internationales, n°41-42, 1995. pp. 235-236
Karl Marx, lecteur dâEugĂšne Sue
La Sainte Famille, rĂ©digĂ©e en 1844, paraĂźt en fĂ©vrier 1845. Cet ouvrage, qui, Ă lâorigine, ne devait pas dĂ©passer les dimensions dâune brochure, est intĂ©ressant Ă plus dâun titre. Tout dâabord, il est le premier qui soit dĂ» Ă la collaboration de Marx et Engels. En second lieu, il marque une Ă©tape dans lâĂ©volution de la pensĂ©e de ces deux auteurs, qui se sĂ©parent Ă ce momentâlĂ de maniĂšre dĂ©cisive des Jeunes HĂ©gĂ©liens dont ils avaient Ă©tĂ© pendant quelques annĂ©es trĂšs proches. Le titre initiale..
Lâimage de la RDA dans LâHumanitĂ© et dans Le Monde de 1969 Ă 1989
Les convenances acadĂ©miques et lâhonnĂȘtetĂ© scientifique commandent dâabord de justifier la limitation du corpus. Il aurait Ă©tĂ© possible dâĂ©largir le champ de lâinvestigation Ă la radio et Ă la tĂ©lĂ©vision françaises, mais, outre que cela nâaurait pas considĂ©rablement ouvert lâĂ©ventail des reprĂ©sentations proposĂ©es, le risque aurait Ă©tĂ© de se limiter Ă la constatation de lâitĂ©ration de poncifs au demeurant facilement interprĂ©tables, comme par exemple les images de militaires de la RDA dĂ©filant ..
AvantâPropos
Les textes ici rassemblĂ©s correspondent pour l'essentiel aux contributions prononcĂ©es lors d'une journĂ©e d'Ă©tudes organisĂ©e par Gilbert Krebs et moiâmĂȘme le 31 mai 2002, Ă l'UFR d'allemand de la Sorbonne Nouvelle (Paris III). L'idĂ©e nous en est venue Ă partir d'un double constat. D'une part, en France tout au moins, la recherche sur la fonction historique, sociĂ©tale, culturelle et idĂ©ologique de la jeunesse et du sport n'a commencĂ© Ă se dĂ©velopper que rĂ©cemment, alors que le discours sur la j..
Lâinfluence des pays de lâEst sur les changements en rda
Les changements intervenus en RDA depuis la fin de lâĂ©tĂ© 1989 se situent au milieu dâune pĂ©riode qui a Ă©tĂ© marquĂ©e des bouleversements qui ont atteint la quasi-totalitĂ© des pays de lâEst, Ă lâexception peut-ĂȘtre de lâAlbanie. Avant le mouvement qui a entraĂźnĂ© lâĂ©viction de Honecker, lâUnion SoviĂ©tique avait entamĂ© une modification radicale, mais progressive, de sa conduite politique Ă lâinitiative de M. Gorbatchev. Dans des conditions diffĂ©rentes, et plus rĂ©cemment, la Pologne et la Hongrie a..