Vous êtes ici : Accueil / Recherches / Equipes / SYSCO2 / Oceanflux

Oceanflux

Par Webmaster Legos Dernière modification 08/09/2014 10:25

Objectives:

Reconstruction of super-resolution oceanic pCO2 and air-sea CO2 fluxes at the air-sea interface in the Eastern Boundary Upwelling systems using remotely sensed product combinations either from the atmosphere or the ocean to properly assess the CO2 sources and sinks at small scales

Tools:

Development of a novel multiscale and non-linear method based on the Microcanonical Multifractal Formalism which takes into account the cascading properties of physical variables across the scales in complex signals

Perspectives:

To derive super resolution pCO2 from space from only remotely sensed observations so clearly the most obvious urgent requirement is to have in orbit another Thermal and Near-infrared Sensor for Carbon Observation which will deliver column abundances of atmospheric CO2 with a much denser sampling than GOSAT or SCIAMACHY (i.e. fixed flight pattern of GOSAT led to a very suboptimal sampling of the regions of interest).

To extend our approach to infer DMS air-sea fluxes using EO derived phytoplankton functional types, CODiM (Comparison of Ocean Dimethylsulfide Models) type models, and DMSGO atlas.

Scientific and societal issues

Understanding and quantifying ocean–atmosphere exchanges of the long-lived greenhouse gases (GHGs) such as carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) are important for understanding the global biogeochemical cycles of carbon and nitrogen in the context of ongoing global climate change. The global budgets of these gases are substantially determined by the marine system. Accurately predicting the evolution of the marine CO2 sink and the marine emissions of N2O and CH4 is of great importance for future climate change scenarios as used in studies for the Intergovernmental Panel on Climate Change (Denman et al., 2007).

The ocean can be thought of as a complex system in which a large number of different processes (physical, chemical, biological, atmosphere-ocean interactions, etc.) interact with each other at different spatial and temporal scales. These scales extend from millimeters to thousands of kilometers and from seconds to centuries (Dickey, 2003). In particular, there is a growing body of evidence that the upper few hundred meters of the oceans are dominated by submesoscale activity, covering the range 1-10 km, and that this activity is important to understand global ocean properties (Klein and Lapeyre, 2009). Accurately estimating the sources and sinks of the GHGs at the air-sea interface requires being able to resolve these small scales. However, the scarcity of oceanographic cruises and the lack of available satellite products for GHG concentrations at high resolution prevent from obtaining a global assessment of their spatial variability at small scales. For example, from the in situ ocean measurements the uncertainty of the net global ocean-atmosphere CO2 fluxes is between 20 and 30% (IOCCP, 2007), and could be higher in the Oxygen Minimum Zones (OMZ) of the Eastern Boundary Upwelling Systems (EBUS). This indeed suggests alternative approaches for inferring the CO2 fluxes at high resolution from remotely sensed data. In this project, we study the validity of a novel method to reconstruct maps of surface ocean partial pressure pCO2 and CO2 fluxes at super resolution (4 km) using sea surface temperature (SST) and ocean colour data at this resolution, and CarbonTracker CO2 fluxes data at low resolution (110 km). The responsible process for propagating the information between scales is related to cascading properties and multiscale organization, typical of fully developed turbulence. The methodology, based on the Microcanonical Multifractal Formalism, makes use, from the knowledge of singularity exponents, of the optimal wavelet for the determination of the energy injection mechanism between scales. We have applied such a methodology to the study of the Benguela Upwelling System.

General organization

The STSE project was led by Christoph Garbe and Véronique Garçon and articulated along 8 Work Packages including Collection of data, Boundary conditions for model, Estimation of k and pGHG, Resolution and adaptation, Assessment of high resolution, Validation and Comparison.

Partners        

LEGOS (Toulouse), GEOSTAT/INRIA (Bordeaux), University of Heidelberg (Heidelberg, Germany), Karlsruhe Institute for Technology (Karlsruhe, Germany)

Financial support

The STSE from ESA granted for Oceanflux (SOLAS partnership) to LEGOS, GEOSTAT/INRIA University of Heidelberg and Karlsruhe Institute for Technology over the period 2011-2013 with an additional Change Contract Notice of 6 months.

 


Actions sur le document

logo cnes logo IRD Logo université de Toulouse Logo université Paul Sabatier Logo CNRS
Logo bibliothèque OBS Logo Observatoire Midi Pyrénées