My first look at Tropospheric NO2 data for the Pacific NW.
Whats that in Nevada?
Why are the Dutch and US. data sets so different?
Dutch OMI U.S. OMI
So, what has Farren been doing since?
• Converted OMI VCD (molec/cm2) into a mixing ratio for comparison to AIRPACT. Tried uniform PBL, then MM5 PBL.
• This produced good results but caused problems over water (and “assumes” all Tropospheric NO2 is within the PBL)
• Looked at fires (large discrepancy).
• Now: AIRPACT is converted into a VCD value using Press. & Temp. of each Layer and then compared to OMI.
• “Below Cloud” ghost column being considered and we NEED to implement averaging kernels.
• Almost completely automated for monthly comparisons.
Molecules/cm2
February 1, 2007 near 21:00 UTC
AIRPACT – Vertical Column Density – NO2 US OMI – Vertical Column Density – Tropo. NO2
Cloud Fraction over 50% shown as black contour.
After looking at many days, emissions for AIRPACT look low (on average) for non-Seattle urban areas.
Ghosted OMI TROP. AIRPACT OMI – TROP.
Looking at the “I-5 Corridor”
TROPOSPHERE – COLUMN NO2 – March 2007
Residuals:
OMI Pixel Density
March I-5 Area Residuals (OMI - AIRPACT)
-4.00E+15
0.00E+00
4.00E+15
2007
0302
2007
0303
2007
0304
2007
0305
2007
0306
2007
0307
2007
0308
2007
0309
2007
0310
2007
0312
2007
0313
2007
0314
2007
0315
2007
0316
Date
Avg
. Res
idu
al (m
ole
c/cm
2)
-1000
-800
-600
-400
-200
0
200
400
600
800
1000
Nu
mb
er o
f OM
I Po
ints
Avg Residual
Avg Residual w/ Ghost
# of OMI Points
OMI Pixel Density and Cloud Cover greatly influence agreement with Airpact.
Ghost Column looks promising.
SO2 from Mountains?
A high SO2 emission event… can we see it?
Mt. St. Helens – Oct. 7, 2004
Effects of Striping is evident… but the OMI folks are working hard!
What does the Future Hold?• Implement automated comparison of AIRPACT with OMI
(Multiple Species? Make it available on the web?)• Implement Quality Flags and Averaging Kernels for
comparisons (eliminate low pixel density, and high CFRAC)• Evaluate emissions inventory used in AIRPACT for urban
areas.
Grrrrrrrr…. Bad CLOUDS!
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