[Job Details:]The Amazonian forest represents a major contribution to the variations of atmospheric greenhouse gases (GHGs), like CO2 and CH4. However, the exact magnitude of this contribution to the global carbon cycle remains highly uncertain, especially due to the fact that there are very few long term observations in this part of the world.
The regional biospheric fluxes of GHGs can be estimated through two main approaches. The bottom-up method is based on sporadic forest inventories and local measurements of carbon exchange between the ecosystem and the atmosphere, analyzed through terrestrial ecosystem models. On the other hand, the top-down methodology is using the space-time variations of atmospheric mixing ratios which integrate the surface fluxes on a larger scale.
Atmospheric transport models are used to link the observed atmospheric gradients, to the distribution of surface fluxes. In French Guiana, North-East of Amazonia, the Guyaflux station (www.ecofog.gf/fr/fonctionnement/guyaflux/) is equipped for continuous measurements of CO2 and H2O biospheric eddy fluxes (since 2003), and high precision atmospheric mixing ratios of CO2 and CH4 (since October 2009). Those dataset should improve the estimations of the contribution of North-East Amazonia in the CO2 and CH4 budget.
The postdoctoral fellow will be in charge of the analysis of the flux and mixing ratio (CO2 and CH4) measurements at the Guyaflux observatory, in collaboration with the international monitoring stations already running in Amazonia. This region is dominated by trade-wind easterlies coming from the tropical Atlantic Ocean. The analysis of the atmospheric gradients from Atlantic stations (Barbados, Ascencion), the Guyaflux site, and Brazilians stations (Santaren, Arembepe) will provide information about the regional CO2 and CH4 fluxes distribution.
In addition to the low troposphere monitoring network, other dataset may be used like the European CARIBIC project in the high troposphere, or remote sensing CH4 observations. The applicant will analyze the available dataset by using the atmospheric inversion scheme develops at LSCE, with the objective to assess the carbon fluxes (CO2 and CH4) and their uncertainties in Amazonia.
Cooperation is foreseen with various research groups in Latin America and the NOAA CarbonTracker team. General information and application procedure: The salary will depend on the experience of the applicant (about 2600 € net/month for a young research fellow). The selected applicant will work at LSCE, Gif sur Yvette, France, but will need to travel 2-3 times to Kourou, French Guiana (2-3 weeks each time). The deadline to submit applications is May 31, 2010. The contract could start in July/August 2010 for a duration of 12 months. Applicants should submit a CV, list of publications, and a short statement of research interests to Damien BONAL (bonal@nancy.inra.fr) and Michel RAMONET (michel.ramonet@lsce.ipsl.fr). | 
Biogeosciences-Academic
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