CNRS - Centre National de Recherche Scientifique

The postdoctoral researcher will be based at LISA (Inter-University Laboratory for Atmospheric Systems – http://www.lisa.u-pec.fr), within the Modelling group. He/she will work, under the supervision of Marie Camredon (MCF UPEC/LISA, Marie.Camredon@lisa.ipsl.fr ) and Matthias Beekmann (DR CNRS/LISA, Matthias.Beekmann@lisa.ipsl.fr). The postdoctoral researcher will benefit from LISA’s extensive expertise in 0D modelling and explicit chemical mechanisms, with contributions to the supervisory team from, Richard Valorso (IR CNRS/LISA, co-developer of GECKO-A) and Bernard Aumont (PR UPEC/LISA), in addition to Marie Caredon, and in 3D modelling with the support of Guillaume Siour (IR/CNRS/LISA, head of the national CHIMERE tool) and Arineh Cholakian (IE/CNRS/LMD), in addition to Matthias Beekmann. The research will be carried out as part of the ADEME funded ECLAT project (Learning from Summer 2022: what will air quality be like in a future climate?).

LISA (Inter-University Laboratory for Atmospheric Systems), UMR CNRS 7583, is a joint research unit of the University of Paris-Est Créteil, the University of Paris Cité and the CNRS. It forms part of the EFLUVE Observatory for Universe Sciences and the IPSL Research Federation. Its main areas of research focus on understanding the behaviour of terrestrial and planetary atmospheres, and the impacts associated with changes in atmospheric composition caused by human activities. The methods used are based on real-atmosphere observations, experimental laboratory simulations and numerical modelling.

Homepage: http://www.lisa.u-pec.fr

Volatile organic compounds (VOCs) present in the atmosphere affect air quality and the climate. Indeed, they act as precursors to the photochemical formation of so-called secondary pollutants, in particular gaseous ozone, and a major proportion of the organic fraction of fine particulate matter in the condensed phase. The complex chemistry of VOC oxidation is linked to the production, transformation and loss of free radicals (OH, HO₂, RO₂, etc.), which constitute the atmosphere’s oxidising capacity. This chemistry can be explicitly modelled, involving millions of reactions, in highly detailed chemical mechanisms such as the Master Chemical Mechanism (MCM) developed in the UK or those generated using LISA’s GECKO-A tool (https://geckoa.lisa.u-pec.fr). However, it is represented in a highly simplified manner, involving a few hundred reactions, in the reduced chemical mechanisms commonly used in chemistry and transport models. These reduced chemical mechanisms were developed to represent ozone chemistry. Their ability to predict the concentrations of its precursors – in particular those of VOCs and radicals – and to be applied to future climatic conditions is only poorly documented.

This postdoctoral project therefore aims to assess the ability of reduced chemical mechanisms to represent the concentrations of gaseous compounds – and in particular those of VOCs and radicals – in the context of climate change.

The method will involve comparing, within a box model, several reduced mechanisms (MELCHIOR, SAPRC-07, SAPRC-22) – which are those currently used in the CHIMERE chemistry and transport model (https://www.lmd.polytechnique.fr/chimere/) – with an explicit reference mechanism generated by GECKO-A. The simulations will focus on France during the summer of 2022, characterised by several heatwave periods, and can therefore be used as an analogue for a future climate. Discrepancies between the mechanisms’ predictions will be documented for ozone, nitrogen oxides and radicals, as well as for the reactivity of VOCs with respect to OH and NO₃. This comparison is an essential step in the evaluation of chemistry and transport models.

Please candidate via the central CNRS site

https://emploi.cnrs.fr/Offres/CDD/UMR7583-ISALAM-007/Default.aspx