scilov-10 validation of sciamachy nadir operational no 2 product f. azam, a. richter, m. weber, h....
TRANSCRIPT
SCILOV-10Validation of SCIAMACHY nadir
operational NO2 product
F. Azam, A. Richter, M. Weber, H. Bovensmann and J. P. Burrows
ESA/ESRIN, Frascati, Italy26-02-2014
Contents:
Datasets
NO2 total column inter-comparisons
Relative differences
Bias
Conclusion/Outlook
1
ESA /DLR (SCIAMACHY) vs IUP(SCIAMACHY and GOME2) NO2 main retrieval differences
2
ESA/DLR v5.02 IUP (SCIA+GOME2)
Processors: BIRA-IASB (SDOAS) IUP (DOAS)
Spectral range 426.5-451.5 nm 425 -450 nm
Max. SZA 89° 85°
AMF LIDORT code SCIATRAN
Cloud parameters OCRA/SACURA FRESCO
See for details; Richter et al. 2005, 2011 and SCIAMACHY Level 2 version5.02 products Readme file
3
ESA/DLR and IUP SCIAMACHY :
ESA/DLR and IUP SCIAMACHY NO2
monthly mean zonal means (5°x5° latitude bins)
ESA/DLR amounts relatively higher than IUP at high latitudes
4
Relative differences comparisons:
Relative differences between the monthly mean zonal means of ESA/DLR and IUP SCIAMACHY NO2 datasets for the time span 2002-2012.
In general very good agreement within ±5%
differences at high latitudes reach ~15%
(ESA-IUP)/IUP
5
ESA/DLR SCIAMACHY and GOME2 :
ESA/DLR SCIAMACHY and IUP GOME2 NO2 monthly mean zonal means (5°x5° latitude bins)
ESA/DLR amounts higher than GOME2 at higher latitudes and tropics
6
At higher latitudes and tropics, seasonality in differences, reaches +20 %
elsewhere good agreement within 5%
Relative differences comparisons:
Relative differences between the monthly mean zonal means of ESA/DLR SCIAMACHY and IUP GOME2 NO2 datasets for the time span 2007-2012.
(ESA-GOME2)/GOME2
13
Bias comparisons:
Relative differences between the monthly mean zonal means of ESA/DLR and IUP SCIAMACHY NO2 datasets averaged over the time span 2002-2012.
almost stable offset with a strong statistical dispersion at higher latitude
insignificant bias of ~ 0.8%.
13
Bias comparisons:
Relative differences between the monthly mean zonal means of ESA/DLR SCIAMACHY and IUP GOME2 NO2 datasets averaged over the time span 2007-2012.
positive bias ~ 6%
significant offset at ~ 40 – 60N
9
Conclusions
ESA/DLR SCIAMACHY NO2 total column v5.02 compared with scientific IUP products derived from SCIAMACHY and GOME2 measurements
The SCIAMACHY datasets agree quite well (~5%) with the exception of high latitudes where the differences can reach 15%
Probable reasons: differences in max. limit of SZA, the differences in the air mass factors and input as cloud parameters etc
ESA/DLR and GOME2 data show large differences at tropics and high latitudes that can reach 20%; significant offset ~6.0% observed around
40-60N
Possible reasons: differences in overpass time, differences in max. limit of SZA, the differences air mass factors, input to the processors. SCIAMACHY captures more structured tropospheric signals due to its better spatial resolution, this could explain large differences observed at the tropics
10
Outlook/Recommendations
Comparisons of NO2 with ground based measurments
Studies on scan angle dpendency should be a part of future operational nadir validation activities.
Thank You