adjoint tm5

Adjoint TM5Maarten KrolPeter Bergamaschi, Jan Fokke Meierink, Henk Eskes, Sander Houweling

Why an Adjoint TM5?Concentrations on a station depend on emissionsInteresting quantity: dM(x,t)/dE(I,J,t)How does a station concentration at t changes as a function of emissions in gridbox (I,J) at time t?Inverse problem: from measurements M (t) --> E(I,J,t)

AdjointdM(t)/dE(I,J) (constant emissions) can be calculated with the adjoint in one simulationM0 = f(E0(I,J))M(t) = M0 + dM(t)/dE(I,J)*(E(I,J)-E0(I,J))Only if the system is linear!Example: MCF at Finokalia

Finokalia MINOS 2001 measurements

FinokaliaIntegrations from M(t) back to july, 15.Forcing at station rm(I,J,1) = rm(I,J,1) + forcing (at averaging period t, t+dt)Adjoint chemistryAdjoint emissions give dM(t)/dE(I,J)

Clean

Dirty

Clean

Dirty

Clean

Dirty

Clean

Dirty

Prior MCF emission distribution

ProcedureMinimise

With

Posterior MCF emissions:

penalty if over sea

apri=pland

ConclusionsResults sensitive to prior informationNot surprising: 8 observations 1300 unknownsEmissions required: 10-30 gG/yearHow to avoid negatives?

Next Steps (to be done)Prior Informationnon-negativefull covariance matrixFull 4Dvar, starting with obtained solution as starting guess emissionsInfluence station sampling, BL scheme, .Faster calculations (parallel version?)