Slides for IPCC

Inverse Modeling of CO 2 Air Parcel Sources Sinks wind Sample Changes in CO 2 in the air tell us about sources and sinks Atmospheric budgets, or “inversions”

3 Basic Atmospheric CO 2 Inversion Components GPP ER Lagrangian Particle Dispersion Model (LPDM) with Regional Atmospheric Modeling System (RAMS) Calibrated CO 2 concentrations Observations from Flux Towers SiB3 model of biosphere fluxes Fossil Fuel Emissions Boundary Conditions WLEF Tower (Park Falls WI, USA)

4 “Observed” at 2PM on 7/7/2004: 368 ppm “Calculated” for 2PM on 7/7/2004: 370 ppm - 3 ppm + 1 ppm - 2 ppm = 366 ppm WLEF Tower -2 ppm 1 ppm -3 ppm 370 ppm Transport Model: Conceptualizing Carbon drawdown in upwind areas must be too strong since the observed CO 2 at the tower is higher than what we predict Final: 366 ppm

Black: air parcels in contact with surface Red: air parcels reach lateral boundaries (20 days of “upstream” transport in 50 seconds) SiB-RAMS-LPDM Back-Trajectories from WLEF Tower (400 m TV tower near Park Falls, WI)

Biome Mean Contributions (ppm) to Round Lake station CO 2, June-August 2007 GPPRespiration

Inversion Results for 2004: Weekly NEE corrections A priori NEE calculated by Simple Biosphere Model (SiB3) Difference from a priori NEE calculated by inversion model Posterior NEE via the inversion (best optimized guess).

Regional Atmospheric CO2 Inversions Need good representation of transport Need good boundary conditions of CO2 from global inversion runs (e.g. CarbonTracker) Need reasonably accurate a prior guess of NEE patterns (e.g. crops) Can be difficult to partition out sink/source components in policy- relevant ways Need lots of concentration data Computational demands Implicitly accounts for all surface sources and sinks of CO2 Far more cost effective than inventory-based methods Great temporal resolution with in-situ instruments (hourly or less on measurements) Policy relevant inversion results (i.e. regional) PROSCONS

*Big Picture* 4 MgC -4 MgC 1.5 MgC 2007 CarbonTracker Annual NEE Estimate 2007 SiB-CROP a priori NEE Estimate Carbon Sink: 318 TgC NEE, MCI (2007) Carbon SINK: 81 TgC NEE, MCI (2007) 2007 Inventory Annual NEE Estimate Carbon SINK: 130 TgC NEE, MCI (2007) Are the inventory data and the inversion data reconcilable? Are the means relatively close? Does the inventory mean sit within the confidence bounds of the inversion results? What are the sensitivities of the inversion to difficult to quantify uncertainties, e.g. variations in transport and inversion setup. 2 MgC -2 MgC

Mean daily NEE (weekly for summer months) for MCI region