1 / 29

Properties of Urban NO 2 Fields from OMI Measurements

Properties of Urban NO 2 Fields from OMI Measurements. Edward A. Celarier UMBC/GEST James F. Gleason NASA/GSFC Thomas P. Kurosu HSAO/CfA Jennifer G. Murphy U of Toronto Jeffrey A. Geddes U of Toronto Eric J. Bucsela SSRI, Inc. Bojan R. Bojkov UMBC/GEST Christian Retscher UMBC/GEST.

ivie
Download Presentation

Properties of Urban NO 2 Fields from OMI Measurements

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Properties of Urban NO2 Fields from OMI Measurements Edward A. Celarier UMBC/GEST James F. Gleason NASA/GSFC Thomas P. Kurosu HSAO/CfA Jennifer G. Murphy U of Toronto Jeffrey A. Geddes U of Toronto Eric J. Bucsela SSRI, Inc. Bojan R. Bojkov UMBC/GEST Christian Retscher UMBC/GEST American Geophysical Union Spring Meeting 2008

  2. OMI in a Nutshell EOS-Aura Spacecraft ORBIT: Polar, sun-synchronous, 97 minute period Key component of the A-Train 1345 Local equator crossing time (ascending node) OPERATIONS: Launched July 15, 2004 Nearly flawless, continual operation since launch to present

  3. OMI in a Nutshell OMI Instrument Hyperspectral radiometer Three spectral bands UV1 270-314 nm UV2 306-380 nm Visible 350-500 nm Simultaneous spectra in 60 fields of view cross-track, covering 2600 km Scan is just wide enough that scans from successive orbits “touch” at equator

  4. OMI in a Nutshell Level-2 (and some Level-3) products being produced from OMI measurements: Ozone O3 Total column Nitrogen dioxide NO2 Total, stratospheric, tropospheric columns Aerosols Aerosol index, Single-scatt. albedo, opt thick Cloud properties Fractional coverage, height Sulfur dioxide SO2 Bromine oxide BrO Chlorine dioxide OClO Formaldehyde HCHO Glyoxal CHOCHO

  5. OMI NO2 Data Products(Publicly available) • Level-2 • Stratospheric column NO2 • Tropospheric column NO2 • Total column NO2 • Level-2G • Selected Level-2 data fields on 1x1 grid • Level-3 (coming soon) • Total column • Tropospheric column • Cloud-screened (30%)

  6. NO2 in Urban Areas

  7. NO2 in Urban Areas

  8. NO2 in Urban Areas

  9. NO2 in Urban Areas

  10. NO2 in Urban Areas

  11. NO2 in Urban Areas

  12. NO2 in Urban Areas

  13. NO2 in Urban Areas

  14. Ground-based NO2 measurements Thermo Scientific (TECO) 42C instrument Measures NO and NO2. Detection limit ~ 50 pptv NO2 Ubiquitous for air quality measurements in N America. Samples 4-10 m above ground. Measurements made every 1 minute, compiled into 1 hour averages. For comparison to OMI (1330 LT), used 1100 to 1500 window. Measurements may be biased positive due to peroxyacetyl nitrates (PANs).

  15. The Challenge: How to use OMI measurements to complement in situ measurements of NO2? • OMI effectively averages over ~400 km2 regions (comparable to the size of small urban areas), while in situ samplers making point measurements • OMI views an area of interest in its regional context, which can help determine if anomalous NOx events are associated with extra-urban sources, such as forest fires. • OMI measures integrated column NO2, while samplers measure at fixed height in the boundary layer

  16. OMI vs. Ground-Based Measurements – a start Can we assume … … that the GB measurement is made in a well-mixed layer? … that time-averaged GB measurements reflect spatial averages over moderate distance scales? … that OMI tropospheric NO2 columns are dominated by the boundary layer in urban setting? (I.e. no comparable amount in the free troposphere.)

  17. The Greater Toronto Urban Area (GTA)

  18. The Greater Toronto Urban Area (GTA)

  19. The Greater Toronto Urban Area (GTA)

  20. The Greater Toronto Urban Area (GTA)

  21. The Greater Toronto Urban Area (GTA)

  22. Results Timeseries of OMI/in-situ ratio (monthly means)

  23. Results Monthly climatological average ratio OMI/in-situ

  24. Results

  25. Results

  26. Results

  27. Discussion • OMI can’t “see” NO2 below clouds • To make statistical comparison, the OMI and GB data sets were subjected to the same cloud filtering • The monthly filtered averages in cloudy months are not necessarily representative of the actual below-cloud concentrations • Photochemistry is different below clouds • Dynamics of vertical mixing is different on overcast days • May be that not all the variation between winter/nonwinter OMI/GB ratios is due to boundary layer height, but averages of these ratios are very suggestive that it explains a large part of the variation

  28. Discussion • We are studying a number of other locations • We are interested in using OMI to establish climatological NO2 distributions to aid in air quality assessments, and the identification and characterization of anomalous events • The air quality community can use OMI data to understand the in situ measurements in their regional context

  29. Acknowledgments • Ontario Ministry of the Environment • TECO 42c data • Data are publicly available (6-18 months after measurement) at www.airqualityontario.ca • Aura Validation Data Center • NASA Goddard Space Flight Center

More Related