Interpretation of station data with an adjoint Model

Maarten Krol (IMAU)

Peter Bergamaschi (ISPRA)

Jan Fokke Meierink, Henk Eskes (KNMI)

Sander Houweling (SRON/IMAU)

What is TM5?

• Global model with zoom option

• Two-way nesting

• Mass-conserving / Positive

• Atmospheric chemistry Applications

• Off-line ECMWF

• Flexible geometry

What is TM5?

6x4

3x2

1x1

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 (x,t)

--> E(I,J,t’)

Adjoint TM5

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

• M0(x, t) = f(E0(I,J))

• M(x, t) = M0+dM(t)/dE(I,J)*(E(I,J)-E0(I,J))

• Only if the system is linear!

Adjoint TM5 (4DVAR)

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) + f(t,t+dt) (during averaging period)

• Adjoint chemistry

• Adjoint emissions give analytically: 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

BETTER CONSTRAIN THE PROBLEM

Conclusions

• Emissions seem to come from regions around the black sea!

• 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, ….

• All observations separately (Movie)