Moving towards a Global GHG Constellation: Flux Constraints in the Presence of Intercalibration and Transport Uncertainty
Sean Crowell, University of Oklahoma, scrowell@ou.edu (Presenter)
Lesley Ott, NASA GSFC GMAO, lesley.e.ott@nasa.gov
Chris O'Dell, CSU/CIRA, odell@atmos.colostate.edu
Tommy Taylor, CSU/CIRA, tommy.taylor@colostate.edu
Peter Somkuti, CSU/CIRA, psomkuti@colostate.edu
Berrien Moore III, University of Oklahoma, berrien@ou.edu
The international space-based observing system currently boasts multiple instruments designed for observing CO2, CH4, and NO2 with the goal of targeting emissions: OCO-2, OCO-3, GOSAT, GOSAT-2, TROPOMI, TanSat, and GHGSat-D. In addition, numerous missions are planned that will add to and/or replace these instruments, e.g. GeoCarb, CO2M, GOSAT-GW, Sentinel-5, MethaneSat. The sensor fleet has been shown to constrain surface fluxes of CO2/CH4 at regional and point-source scales. Clouds and generally sparse sampling imply a tremendous potential for using multiple sensors simultaneously to constrain carbon cycle processes. However, instruments are individually calibrated and validated against ground targets, and different instruments are almost certain to suffer from intercalibration errors. Secondly, most retrieval frameworks are designed and tuned for a specific instrument, which complicates use of the retrieved trace gases from two different instruments. Thirdly, atmospheric transport errors are a significant source of uncertainties in regional scale and local scale flux estimates constrained by single instruments, and it is expected that multiple sensors could exacerbate, rather than alleviate, this issue. Finally, the current generation of atmospheric inversion tools is not well-suited to extract the full information content from numerous sensors due to the model resolution in space and time as well as efficiency of the assimilation algorithms. All 4 of these challenges must be tackled before we can make use of the current and future constellation of sensors to constrain fluxes with properly characterized uncertainties.
In this presentation, we will begin to explore the impacts of 1) systematic errors in retrievals arising from intercalibration errors and 2) sampling differences on transport on the posterior uncertainties in estimated surface fluxes of CO2 in the context of NASA’s Carbon OSSE project. In particular, we take the first step towards constraining fluxes with a geostationary satellite modeled on GeoCarb and a polar orbiter modeled on OCO-2 in the presence of these errors and explore how the different components affect the uncertainties in the posterior fluxes.
Presentation: Talk_Crowell_120_25.pdf
Presentation Type: Talk
Session: 4.4 Towards an international space-based GHG emission monitoring system
Session Date: Thursday (6/17) 11:30 AM