1. QOS2016-26, 2016. Quadrennial Ozone Symposium of the International Ozone Commission
QUALITY ASSESSMENT OF IASI/Metop-A AND OMI/Aura OZONE COLUMN AMOUNTS BY USING EUBREWNET GROUND-BASED MEASUREMENTS
N. Peinado-Galán (1), X. Calbet (2), O.E. García (3), E. López-Baeza (1), A. Redondas (3), E. Sepúlveda (3), M. E. Koukouli (4), I. Zyrichidou (4), I. Fountoulakis (4), D. Balis (4), A. Bais (4), T. Karppinen (5), J. López-Solano (3), and B. Hernández-Cruz (3)
(1) University of Valencia, Faculty of Physics, Earth Physics and Thermodynamics Dept, Climatology from Satellites Group, Valencia, Spain. , (2) State Meteorological Agency (AEMET), Madrid, Spain, (3) Izaña Atmospheric Research Center (IARC), State Meteorological Agency (AEMET), Santa Cruz de Tenerife, Spain, (4) Laboratory of Atmospheric Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece, (5) Finnish Meteorological Institute (FMI), Arctic Research Centre, Sodankylä, Finland
ABSTRACT
This work addresses the comparison of IASI (Infrared Atmospheric Sounding Interferometer) on board MetopA and OMI (Ozone Monitoring Instrument) on board Aura to several ground-based Brewer spectrophotometers belonging to the European Brewer network (EUBREWNET) for the period September 2010 to December The focus of this study is to examine how well the satellite retrieval products capture the total ozone column amounts (TOC) at different latitudes and evaluate the different levels of Brewer spectrophotometer data.
On this comparison Level 1 and 1.5 Brewer data will be used to evaluate satellite data, where: 1) Level 1 Brewer data are the TOC calculated with the standard Brewer algorithm from the direct sun measurements; and 2) Level 1.5 Brewer data are Level 1.0 observations filtered and corrected from instrumental issues. The IASI retrievals examined are operational IASI Level 2 products, version 5 from September 2010 to October 2014, and version 6 from October 2014 to December 2015, from EUMETSAT Data Centre, while OMI retrievals are OMI-DOAS TOC products extracted from the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC). 
FACTORS TO BE CONSIDERED IN THE COMPARISON IASI-BREWER-OMI:
A) Collocation criteria:
- Temporal collocation criteria: 1, 2, 3, 4, and 6 hour time difference between the measurements of IASI and Brewer. IASI overpass times at 9:30 local solar time. OMI overpass time over Europe: 12:45 hours (GMT).
- Spatial collocation: 5 collocation distances: 250 km, 200 km, 150 km, 100 km and 50 km between IASI and Brewer measurements. OMI spatial grid: 0.25º lat, 0.25º lon over station position.
STUDY AREA
Sodankylä (Finland): high-latitude station (67.42°N, 26.59°E, 180 m a.s.l.)
Thessaloniki (North of Greece): mid-latitude station (40.63º N, 22.96º E, 36 m a.s.l).
Izaña Atmospheric Observatory (IZO) (Tenerife, Canary Islands, Spain): sub-tropical station (28.31º N, 16.50º W, 2367 m a.s.l.)
B) Vertical Sensitivity: IASI, OMI and Brewer techniques have different vertical sensitivity, what affects the comparison.
IASI VERTICAL SENSITIVITY (from IASI v6)
Median of the sum along the row AVKS distinguishing for each season
O3 row AVKs for typical measurement conditions at IZO
COMPARISONS
Brewer 1.0/1.5 vs OMI-DOAS v3 vs IASI L2 v5 :
Comparison of total atmospheric integrated ozone from September 2010 to October 2014.
Brewer 1.0/1.5 vs OMI-DOAS v3 vs IASI L2 v6:
Comparison of total atmospheric integrated ozone from October 2014 to December 2016.
Analysis based on the possible presence of clouds and the topography and the surface type (land/water) within the IASI v6 IFOV is presented.
The IASI’s response to real atmospheric O3 variability strongly depends on its vertical sensitivity.
The vertical structures that are detectable by the IASI remote sensor are given by the AVKs.
IASISensitive to the max O3 concentrations in the stratosphere and to the upper troposphere/lower stratosphere regions, but weak sensitivity in the lower troposphere.
RESULTS
IZO (28.31º N, 16.50º W, 2367 m a.s.l.)
SUMMARY 3 STATIONS: TEMPORAL COLOCATION CRITERIA 1h
Flag cldness=1 Flag Lansea=0
Colocation criteria: 100 km and 1h
Mean and STD decreases for Brewer data L1.5 except in IZO
Corrected in Brewer Level 2.0
Differences are not independent of spatio-temporal criteria.
100km and 1h spatio-temporal windows is a good compromision between the scatter and the nº of coincidences.
p.e TOC Temporal Serie in IZO
Thessaloniki (40.63º N, 22.96º E, 36 m a.s.l.)
Sodänkyla (67.42°N, 26.59°E, 180 m a.s.l.)
Flag cldness=1 Flag Lansea=0
Colocation criteria: 100 km and 1h
Flag cldness=1 Flag Lansea=0
Colocation criteria: 100 km and 1h
Mean differences decrease as space window increases
systematically difference
between IASI land and ocean data
Ocean  +RD
Land  -RD
SUMMARY TABLE: Spatial window 100km. Temporal window +1h
Cldness=[1,2]
Land/sea=1
Cldness=[1,2]
Land/sea=0
Cldness=[1,2]
Land/sea=0
Sodänkyla. 01/09/2014 – 31/12/2015
IZO. 01/09/2014 – 31/12/2015
Thessaloniki . 01/09/2014 – 31/12/2015 R
MEAN RD (%)
STDV RD (%)
BIAS (DU) N
IASI v6 vs BREWER L1.5
0,97
3,1
3,9
10,7
150
IASI v6 vs OMI
4,2
4,3
14,2
OMI vs BREWER L1.5
0,99
-1,0
2,6
-3,4 R
MEAN RD (%)
STDV RD (%)
BIAS (DU) N
IASI v6 vs BREWER L1.5
0,90
3,6
3,1
6,5
484
IASI v6 vs OMI
0,83
2,9
3,7
3,4
OMI vs BREWER L1.5
0,92
0,8
2,4
2,1 R
MEAN RD (%)
STDV RD (%)
BIAS (DU) N
IASI v6 vs BREWER L1.5
0,94
3,2
3,1
3,6
197
IASI v6 vs OMI
0,90
1,9
4,2
1,6
OMI vs BREWER L1.5
0,96
-1,6
2,4
-0,8
Thessaloniki. 01/01/2013 – 31/08/2014
Sodänkyla. 01/09/2010 – 31/08/2014
IZO. 01/09/2010 – 31/08/2014 R
MEAN RD (%)
STDV RD (%)
BIAS (DU) N
IASI v6 vs BREWERL1.5
0,90
0,9
3,4
9,3
620
IASI v6 vs OMI
0,89
-0,2
3,1
-3,6
OMI vs BREWER L1.5
0,91
1,2
3,3 R
MEAN RD (%)
STDV RD (%)
BIAS (DU) N
IASI v6 vs BREWER L1.5
0,93
-1,9
3,1
-6,1
466
IASI v6 vs OMI
0,87
-0,5
4,2
-1,8
OMI vs BREWER L1.5
0,92
-1,3
3,3
-4,4 R
MEAN RD (%)
STDV RD (%)
BIAS (DU) N
IASI v6 vs BREWER L1.5
0,97
2,4
3,4
7,6
458
IASI v6 vs OMI
4,0
10,3
OMI vs BREWER L1.5
0,99
-0,9
2,2
-2,8
CONCLUSIONS
The comparison of total ozone columns as retrieved by IASI v6 and IASI v5 to coincident ground-based ozone observations (Brewer) and other satellite-based sensor (OMI) show very consistent results at three stations. But IASI shows higher agreement with Brewer than with OMI at all locations.
IASI overestimates TOC measurements registered with all sensors at three stations.
The inter-comparison between IASI and Brewer results are shown to be dependent on the collocation criteria used: being the most ideal case the comparison between data with a max distance of 100 km and 1 hour of time difference between datasets (good scatter and high nº of coincidences). In addition, results show that differences between IASI and ground base measurements depend on cloud cover and topography.
REFERENCES
ACKNOWLEDGEMENTS
- Balis, D., Koukouli, M., Loyola, D., Valks, P., and Hao, N.: O3M SAF second validation report of GOME-2 total ozone products, REF: SAF/O3M/AUTH/GOME2VAL/RP/02, 2008.
- Clerbaux, C., Boynard, A., Clarisse, L., George, M., Hadji-Lazaro, J., Herbin, H., Hurtmans, D., Pommier, M., Razavi, A., Turquety, S., Wespes, C., and Coheur, P.-F.: Monitoring of atmospheric composition using the thermal infrared IASI/MetOp sounder, Atmos. Chem. Phys., 9, 6041–6054, 2009.
- Scarnato, B., J. Staehelin, R. Stübi, and H. Schill (2010), Long‐term total ozone observations at Arosa (Switzerland) with Dobson and Brewer instruments (1988–2007), J. Geophys. Res., 115, D13306, doi: /2009JD
We thank the European Brewer Network ( for providing access to the data and the PI investigators and their staff for establishing and maintaining the sites used in this investigation.