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How Measurements Of Rate Constants At Low Temperature Increase The Predictivity Of Photochemical Models Of Titans's Atmosphere

hal.structure.identifierLaboratoire de Chimie Physique D'Orsay [LCPO]
dc.contributor.authorPERNOT, Pascal
hal.structure.identifierLaboratoire d'Astrophysique de Bordeaux [Pessac] [LAB]
dc.contributor.authorHÉBRARD, Eric
hal.structure.identifierSSE 2009
dc.contributor.authorDOBRIJEVIC, M.
hal.structure.identifierPLANETO - LATMOS
dc.contributor.authorCARRASCO, Nathalie
hal.structure.identifierInstitut des Sciences Moléculaires [ISM]
dc.contributor.authorBERGEAT, A.
hal.structure.identifierInstitut des Sciences Moléculaires [ISM]
dc.contributor.authorHICKSON, K. M.
hal.structure.identifierInstitut de Physique de Rennes [IPR]
dc.contributor.authorCANOSA, André
hal.structure.identifierInstitut de Physique de Rennes [IPR]
dc.contributor.authorLE PICARD, Sébastien D.
hal.structure.identifierInstitut de Physique de Rennes [IPR]
dc.contributor.authorSIMS, Ian R
dc.date.conference2009-10
dc.description.abstractEnKinetic data measured at low temperatures are very sparse; for instance, in state-of-the-art photo-chemical models of Titan atmosphere, less than 10% of the rates have been measured in the relevant temperature range (100-200 K). A consequence is that photochemical models rely mostly on low-T extrapolations by Arrhenius-type laws. There is more and more evidence that this is often inappropriate, and low T extrapolations are hindered by very high uncertainty. The predictions of models based on those extrapolations are expected to be very inaccurate. A dialogue between modellers and experimentalists is necessary to improve this situation. Considering the difficulty of low-T reaction kinetics experiments, the identification of key reactions has to be based on an optimal strategy to improve the predictivity of photochemical models. This can be achieved by global sensitivity analysis, as illustrated on Titan atmospheric chemistry. The main difficulty of this scheme is that it requires a lot of inputs, mainly the evaluation of uncertainties for extrapolated reaction rates. Although a large part has already been achieved by Hébrard et al., extension and validation requires a group of experts. A new generation of collaborative kinetic database is needed to implement efficiently this scheme. The KIDA project, initiated by V. Wakelam for astrochemistry, has been joined by planetologists with similar prospects. A result from these meetings was the reevaluation of the uncertainties associated with measured low-T reaction rates. The impact of this database update on the predicted densities of neutrals species in Titan's atmosphere is remarkable. There is a general precision improvement, but some species densities remain poorly predicted. Using these results, we generated a new list of key reactions, i.e. having a strong impact on the precision of model predictions, for which better estimation will have to be obtained, either experimentally or theoretically.
dc.language.isoen
dc.title.enHow Measurements Of Rate Constants At Low Temperature Increase The Predictivity Of Photochemical Models Of Titans's Atmosphere
dc.typeCommunication dans un congrès
dc.subject.halPlanète et Univers [physics]/Astrophysique [astro-ph]/Astrophysique stellaire et solaire [astro-ph.SR]
dc.subject.halPhysique [physics]/Astrophysique [astro-ph]/Astrophysique stellaire et solaire [astro-ph.SR]
dc.subject.halPlanète et Univers [physics]/Astrophysique [astro-ph]/Planétologie et astrophysique de la terre [astro-ph.EP]
dc.subject.halPhysique [physics]/Astrophysique [astro-ph]/Planétologie et astrophysique de la terre [astro-ph.EP]
bordeaux.pageid. 17.08
bordeaux.volume41
bordeaux.conference.titleDPS Meeting
bordeaux.countryUS
bordeaux.conference.cityPuerto Rico
bordeaux.peerReviewedoui
hal.identifierhal-00426684
hal.version1
hal.invitednon
hal.proceedingsnon
hal.popularnon
hal.audienceNon spécifiée
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-00426684v1
bordeaux.COinSctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.volume=41&rft.spage=id.%2017.08&rft.epage=id.%2017.08&rft.au=PERNOT,%20Pascal&H%C3%89BRARD,%20Eric&DOBRIJEVIC,%20M.&CARRASCO,%20Nathalie&BERGEAT,%20A.&rft.genre=unknown


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