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Airborne MAX-DOAS Measurements Over California: Testing the NASA OMI Tropospheric NO2 ProductAirborne Multi-AXis Differential Optical Absorption Spectroscopy (AMAX-DOAS) measurements of NO2 tropospheric vertical columns were performed over California for two months in summer 2010. The observations are compared to the NASA Ozone Monitoring Instrument (OMI) tropospheric vertical columns (data product v2.1) in two ways: (1) Median data were compared for the whole time period for selected boxes, and the agreement was found to be fair (R = 0.97, slope = 1.4 +/- 0.1, N= 10). (2) A comparison was performed on the mean of coincident AMAX-DOAS measurements within the area of the corresponding OMI pixels with the tropospheric NASA OMI NO2 assigned to that pixel. The effects of different data filters were assessed. Excellent agreement and a strong correlation (R = 0.85, slope = 1.05 +/- 0.09, N= 56) was found for (2) when the data were filtered to eliminate large pixels near the edge of the OMI orbit, the cloud radiance fraction was<50%, the OMI overpass occurred within 2 h of the AMAX-DOAS measurements, the flight altitude was>2 km, and a representative sample of the footprint was taken by the AMAX-DOAS instrument. The AMAX-DOAS and OMI data sets both show a reduction of NO2 tropospheric columns on weekends by 38 +/- 24% and 33 +/- 11%, respectively. The assumptions in the tropospheric satellite air mass factor simulations were tested using independent measurements of surface albedo, aerosol extinction, and NO2 profiles for Los Angeles for July 2010 indicating an uncertainty of 12%.
Document ID
20140012688
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
doi:10.1002/jgrd.50550
Authors
Oetjen, Hilke (California Univ. Los Angeles, CA, United States)
Baidar, Sunil (Colorado Univ. Boulder, CO, United States)
Krotkov, Nickolay A. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Lamsal, Lok N. (Universities Space Research Association Columbia, MD, United States)
Lechner, Michael (Colorado Univ. Boulder, CO, United States)
Volkamer, Rainer (Colorado Univ. Boulder, CO, United States)
Date Acquired
September 26, 2014
Publication Date
July 10, 2013
Publication Information
Publication: Journal of Geophysical Reserach: Atmospheres
Volume: 118
Issue: 13
Subject Category
Geosciences (General)
Report/Patent Number
GSFC-E-DAA-TN10039
Funding Number(s)
CONTRACT_GRANT: NNG11HP16A
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
remote sensing
validation
Nitrogen dioxide

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