1. The new Pandora total ozone algorithm including the retrieval of
effective ozone temperature
Martin Tiefengraber,
Alexander Cede

2. TO3 difference Pandora vs. OMI
Langley, Virginia (38.9, -77.2)
OMI: OMTO3 v8.5
Pandora standard TO3
OMI - Pandora
Seasonal cycle
~ -10 to + 10 DU
Temperature?

3. Pandora standard TO3 algorithm
Fitting window: 310 to 330 nm
Background poly: 4
Offset poly: 0
XSec: Brion / Daumont / Malicet (BDM) 225 K
Absorption free reference (theoretical reference)

4. Include TEff fit TEff fit fails Reasons: Spectral stray light
No absolute
calibration
spectral feature due to stray light
what to say about absolute calibration

5. “Synthetic” ozone-free reference including TEff fit
SC DU
TEff 221 K
Reference:
take noon time data and add estimated SC and TEff.
Only unique set of SC and TEff
SC DU
TEff 228 K
How do we know SC and TEff values?
Auto-Cross-Calibration

6. Auto-Cross-Calibration
∆TEff +5 K
∆TEff 0 K
∆SC +5 DU
∆SC + 0 K
∆SC + 5 K
∆SC 0 K
First guess SC = theoretical reference
First guess TEff = 225K
Minimize difference between:
Day1(refDay1)
and
Day1(refDay2)
up to now:
cumbersome iterative approach

7. Theoretical and synthetic reference
Theoretical reference and best guess synthetic reference
What about additional noise due to TEff fitting?

8. Additional noise when including TEff fit
Additional noise due to TEff fit:
from ~ 1.2 DU
to ~ 1.6 DU
Enhanced point to point variation ↔
TEff variation
Single points retrieval possible
no actual noise estimation!

9. TO3 difference Pandora vs. OMI I
Pandora TO3 retrieval with TEffO3 from TOMS climatology
Seasonal cycle:
~ -10 to +10
~ -9 to +5
Note:
TOMS v8.5 doesn’t use ozone weighted temperature. Instead a Beers law approximation for each layer is applied and the radiance sensitivity is computed.

10. TO3 difference Pandora vs. OMI II
Pandora TO3 retrieval with TEffO3 fitted
Seasonal cycle
~ -10 to +10
~ -9 to +5
~ -9 to +7

11. TO3 difference Pandora vs. OMI III
TEff based on:
TOMS
O3 profile (with TO3 corrected)
fixed temperature climatology
NCEP/NCAR Reanalysis:
actual temperature profile
fixed O3 profile (US std. atmos.)

12. Conclusions / What’s next?
Season cycle (TO3 OMI-Pandora) cannot be explained by temperature only
New field calibration method applied
“Auto-Cross-Calibration”
TEff retrieval reasonable (single points retrieval)
TO3 + TEff retrieval with theoretical reference
Spectral stray light correction (matrix method)
Absolute calibration

13. Thank you very much !

15. Side note: effect of O3 absorption cross section
TO3(Serdyuchenko)
>
TO3(BDM)
TEffO3(Serdyuchenko)
TEffO3(BDM)

16. Backup slide: definition TEff
TEff= i=1 N T i ∗ n O3, i i=1 N n O3, i