Adjoint TM5

Maarten Krol

Peter Bergamaschi, Jan Fokke Meierink, Henk Eskes, Sander

Houweling

Why an Adjoint TM5?

• Concentrations on a station depend on emissions

• Interesting 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’)

Adjoint

• dM(t)/dE(I,J) (constant emissions) can be calculated with the adjoint in one simulation

• M0 = 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

Dirty

Clean

Finokalia

• Integrations 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 chemistry

• Adjoint emissions give dM(t)/dE(I,J)

Clean

Dirty

Clean

Dirty

Clean

Dirty

Clean

Dirty

Prior MCF emission distribution

Procedure

• Minimise

• With

Posterior MCF emissions:

Negatives

Emissions over sea

penalty if over sea

apri=pland

Conclusions

• Results sensitive to prior information

• Not surprising: 8 observations <==> 1300 unknowns

• Emissions required: 10-30 gG/year

• How to avoid negatives?

Next Steps (to be done)

• Prior Information– non-negative– full covariance matrix

• Full 4Dvar, starting with obtained solution as starting guess emissions

• Influence station sampling, BL scheme, ….

• Faster calculations (parallel version?)