Search results for "Ocean"

Simulation de spectres à haute température : une approche statistique du compromis résolution / précision

2010

International audience; Malgré les progrès continus enregistrés dans le domaine de la spectroscopie moléculaire, théorique et expérimentale, les banques de données spectroscopiques disponibles présentent des lacunes importantes, notamment pour l'interprétation des observations des environnements astrophysiques à haute température. Ce constat s'applique en particulier à la molécule de méthane présente dans les atmosphères de nombreux objets astrophysiques. La modélisation du coefficient d'absorption du méthane dans le proche infrarouge et/ou à haute température continue à défier les théoriciens du fait de la complexité intrinsèque de son spectre rovibrationnel. De fait, les analyses à haute …

The present status of methane spectroscopy for planetary applications

2008

International audience

Etat de l'Art des Analyses Raie par Raie des Spectres du Méthane

2008

SPVIEW and XTDS: graphical tools for the analysis and simulation of high-resolution molecular spectra

2007

Fonction de partition du methane à haute température

2008

Titan's surface and atmosphere from Cassini/VIMS data with updated methane opacity

2013

International audience; We present an analysis of Titan data acquired by the Cassini Visual and Infrared Mapping Spectrometer (VIMS), making use of recent improvements in methane spectroscopic parameters in the region 1.3-5.2 μm. We first analyzed VIMS spectra covering a 8 × 10-km2 area near the Huygens landing site in order to constrain the single scattering albedo (ω0) of the aerosols over all of the VIMS spectral range. Our aerosol model agrees with that derived from Huygens Probe Descent Imager/Spectral Radiometer (DISR) in situ measurements below 1.6 μm. At longer wavelengths, ω0 steadily decreases from 0.92 at 1.6 μm to about 0.70 at 2.5 μm and abruptly drops to about 0.50 near 2.6 μm…

Evaluation of observed and modelled aerosol lifetimes using radioactive tracers of opportunity and an ensemble of 19 global models

2015

Abstract. Aerosols have important impacts on air quality and climate, but the processes affecting their removal from the atmosphere are not fully understood and are poorly constrained by observations. This makes modelled aerosol lifetimes uncertain. In this study, we make use of an observational constraint on aerosol lifetimes provided by radionuclide measurements and investigate the causes of differences within a set of global models. During the Fukushima Dai-Ichi nuclear power plant accident of March 2011, the radioactive isotopes cesium-137 (137Cs) and xenon-133 (133Xe) were released in large quantities. Cesium attached to particles in the ambient air, approximately according to their av…

Convective hydration in the tropical tropopause layer during the StratoClim aircraft campaign: pathway of an observed hydration patch

2018

The source and pathway of the hydration patch in the TTL (tropical tropopause layer) that was measured during the Stratospheric and upper tropospheric processes for better climate predictions (StratoClim) field campaign during the Asian summer monsoon in 2017 and its connection to convective overshoots are investigated. During flight no. 7, two remarkable layers are measured in the TTL, namely (1) the moist layer (ML) with a water vapour content of 4.8–5.7 ppmv in altitudes of 18–19 km in the lower stratosphere and (2) the ice layer (IL) with ice content up to 1.9 eq. ppmv (equivalent parts per million by volume) in altitudes of 17–18 km in the upper tropo…

Précipitations à Madagascar, Mayotte, la Réunion et les Îles Éparses durant la saison des pluies (1971-1999) : rôle et contribution des talwegs tropi…

2014

7 pages; International audience; Cette étude, sur la base d’un jeu de données pluviométriques original, recherche les mécanismes à l’origine de lavariabilité spatiotemporelle des précipitations journalières observées sur Madagascar, Mayotte, La Réunion et les îlesÉparses. L’étude se concentre sur le début et le coeur de l’été austral de 1971 à 1999. Un focus sur la contribution desTalwegs Tropicaux-Tempérés (TTT) est réalisé. Dans une première partie, une classification sur les séries de précipitationsde vingt-neuf stations a mis en évidence six types de jours et de mécanismes associés. La classe sèche est associée à desanomalies cycloniques, deux des cinq classes dont associées à des TTT, …

Multi-Resolution error analysis of predicted absorption coefficients. Method and computer implementation. Application to the infrared spectrum of met…

2009

A general method for the estimation of the confidence interval of molecular absorption coefficients is presented. It combines statistical numerical experiments with analytical calculations. The method uses line parameter predictions (position and intensity) with known estimated uncertainties. The propagation of errors from line parameters to absorption coefficients or cross-sections are analyzed in detail as a function of the resolution. This work is especially intended to provide expert information for applications requiring theoretical predictions for which the present state of the art of line by line high-resolution modeling is not accurate enough to meet the experimental precision. As a…