Adjoint TM5
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Transcript of Adjoint TM5
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?)