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Source evaluation of aerosol precursors with the adjoint of GEOS-Chem. Daven K. Henze with Amir Hakami and John H. Seinfeld Caltech, Chemical Engineering Support from: NSF, EPA, TeraGrid and JPL Supercomp., W. & S. Davidow Fellowship. Forward sensitivity. Adjoint sensitivity.
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Source evaluation of aerosol precursors with the adjoint of GEOS-Chem Daven K. Henze with Amir Hakami and John H. Seinfeld Caltech, Chemical Engineering Support from: NSF, EPA, TeraGrid and JPL Supercomp., W. & S. Davidow Fellowship
Adjoint method Depending on “model response,” can be used for: Sensitivity analysis: quantifying influence of uncertain model parameters (emissions, reaction rates, …) Attainment studies: assessing the effectiveness of emissions abatement Inverse modeling: using large data sets, optimizing parameters on resolution commensurate with forward model.
Gas-phase chemistry Cloud processing Aerosol thermo Gas-phase emissions SO2, NOx, NH3 Aerosol SO42-, NO3-, NH4+ Forward Model: GEOS-CHEM Model Description, v6-02-05 (Bey et al., 2001; Park et al., 2004) • GEOS-3 Assimilated meteorology • 4°x5°(Global) resolution, 30 vertical levels • HOx - NOx - HCfullgas-phase chemistry • Aerosols - Secondary inorganic - Carbonaceous (primary) aerosol - Sea salt - Dust
The adjoint of GEOS-Chem: hybrid • Discrete (adjoint of algorithm) • KPP (Damian et al., 2002; Sandu et al., 2003; Daescu et al., 2003) • - chemistry • TAMC(Giering & Kaminski, 1998) and manual • - aerosol thermo • - cloud processing • - convection • Manual • - turbulent mixing • - deposition • - heterogeneous chemistry • Continuous (adjoint of equation) • - advection(Vukicevic et al., 2001; Thuburn and Haine, 2001; Liu and Sandu, 2006; Hakami et al., 2006; Singh et al., 2006) Resources - CPU: tadj ~ 1.5 tfwd As || as the fwd model - HD: 45 GB for 1 month (4x5) Henze et. al, 2007
Testing the Adjoint Model: Gradient Check Check gradient using finite difference calculation cost function control parameter adjoint sensitivity Component-wise analysis affords domain wide points-of-comparison
Testing the Adjoint: single processes, 1 week (thermo only)
Testing the Adjoint: single processes, 1 week (thermo only) (chem only)
GEOS-Chem Adjoint: full chemistry Initial Conditions (all species and tracers) Emissions sectors - NOx (lightning, anthro) - SOx (anthro, bioburn, biofuel, ships) - NH3 (anthro, bioburn, biofuel, natural) - OC/BC (anthro, bioburn, biofuel) - others are easy to add Reaction rate constants - All reactions - gas-phase emissions (NO, ISOP, ACET, etc.) - dry deposition
www.epa.gov Pollution = non-attainment of NAAQS for PM2.5 of 15 µg/m3 (annual ave)
Adjoint method Depending on “model response,” can be used for: Sensitivity analysis: quantifying influence of uncertain model parameters (emissions, reaction rates, …) Attainment studies: assessing the effectiveness of emissions abatement Inverse modeling: using large data sets, optimizing parameters on resolution commensurate with forward model.
NH4+ non-attainment July 2001 Attainment -- Aerosols Define cost function ~ non-attainment for PM2.5
Benefit (Hakami et al., 2006) anth NH3 Emissions (normalized) Sensitivities (normalized) Responsibility Effectiveness Attainment -- Aerosols Define cost function ~ non-attainment for PM2.5 NH4+ non-attainment
April NH3 controls effective in spring, SO2 in summer. Attainment -- Aerosols Seasonal variability Emissions Sensitivities anth NH3 stack SOx July Also consider $$ (Pinder et. al, 2007)
Attainment -- Aerosols Long range transport Emissions Sensitivities w.r.t. surface SOx Influences concentrations, not AQ attainment Future emissions scenarios? Climate change? Cost?
Adjoint method Depending on “model response,” can be used for: Sensitivity analysis: quantifying influence of uncertain model parameters (emissions, reaction rates, …) Attainment studies: assessing the effectiveness of emissions abatement Inverse modeling (Data Assimilation): using large data sets, optimizing parameters on resolution commensurate with forward model.
Model: Diff: MOD - OBS Observed Aerosol (IMPROVE): January 2002 SO4 NIT Observed:
Inverse Modeling using Adjoint Model Inverse Model Optimization Improved Estimate Parameter Estimate Gradients (sensitivities) Forward Model Adjoint Model t0 tf tf t0 Predictions Adjoint Forcing - Observations
Optimized Anth NH3 1 . . . 10 [kg/box/s] scaling f = ln( e10/e1) Emissions Scaling Factors NIT DIFF(GC-IMPRV) 1 . . . 10 Domain wide NH3 adjustments similar to inverse modeling study by Gilliland et al., 2006.
Optimized Anth NH3 1 . . . 10 [kg/box/s] scaling f = ln( e10/e1) Emissions Scaling Factors NH4+ CASTNet
The End Thanks!