Retrieving tropospheric nitrogen dioxide from the Ozone Monitoring Instrument: effects of aerosols, surface reflectance anisotropy, and vertical profile of nitrogen dioxide 1Laboratory for Climate and Ocean-Atmosphere Studies, Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing 100871, China
07 Feb 2014
2Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada
3Atomic and Molecular Physics Division, Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA
4Royal Netherlands Meteorological Institute, De Bilt, the Netherlands
5Fluid Dynamics Lab, Eindhoven University of Technology, Eindhoven, the Netherlands
6RT Solutions Inc., Cambridge, Massachusetts 02138, USA
7IAP/CAS, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
8BIRA-IASB, Belgian Institute for Space Aeronomy, Brussels, Belgium
9Instituut voor sterrenkunde, KU Leuven, Celestijnenlaan 200D, 3001 Heverlee, Belgium
10Center for Environmental Remote Sensing, Chiba University, 1–33 Yayoicho, Inage-ku, Chiba 263-8522, Japan
Received: 02 Jul 2013 – Published in Atmos. Chem. Phys. Discuss.: 14 Aug 2013 Abstract. Retrievals of tropospheric nitrogen dioxide (NO2) from the Ozone
Monitoring Instrument (OMI) are subject to errors in the treatments of
aerosols, surface reflectance anisotropy, and vertical profile of NO2.
Here we quantify the influences over China via an improved retrieval
process. We explicitly account for aerosol optical effects (simulated by
nested GEOS-Chem at 0.667° long. × 0.5° lat.
and constrained by aerosol measurements), surface reflectance anisotropy,
and high-resolution vertical profiles of NO2 (simulated by GEOS-Chem).
Prior to the NO2 retrieval, we derive the cloud information using
consistent ancillary assumptions.
Revised: 18 Dec 2013 – Accepted: 07 Jan 2014 – Published: 07 Feb 2014
We compare our retrieval to the widely used DOMINO v2 product, using MAX-DOAS measurements at three urban/suburban sites in East China as
reference and focusing the analysis on the 127 OMI pixels (in 30 days) closest to the
MAX-DOAS sites. We find that our retrieval reduces the interference of
aerosols on the retrieved cloud properties, thus enhancing the number of
valid OMI pixels by about 25%. Compared to DOMINO v2, our retrieval
better captures the day-to-day variability in MAX-DOAS NO2 data
(R2 = 0.96 versus 0.72), due to pixel-specific radiative transfer
calculations rather than the use of a look-up table, explicit inclusion of
aerosols, and consideration of surface reflectance anisotropy. Our retrieved
NO2 columns are 54% of the MAX-DOAS data on average, reflecting the
inevitable spatial inconsistency between the two types of measurement,
errors in MAX-DOAS data, and uncertainties in our OMI retrieval related to
aerosols and vertical profile of NO2.
Sensitivity tests show that excluding aerosol optical effects can either
increase or decrease the retrieved NO2 for individual OMI pixels with
an average increase by 14%. Excluding aerosols also complexly affects the
retrievals of cloud fraction and particularly cloud pressure. Employing
various surface albedo data sets slightly affects the retrieved NO2 on
average (within 10%). The retrieved NO2 columns increase when the
NO2 profiles are taken from MAX-DOAS retrievals (by 19% on average)
or TM4 simulations (by 13%) instead of GEOS-Chem simulations. Our
findings are also relevant to retrievals of other pollutants (e.g., sulfur
dioxide, ormaldehyde, glyoxal) from UV–visible backscatter satellite
Citation: Lin, J.-T., Martin, R. V., Boersma, K. F., Sneep, M., Stammes, P., Spurr, R., Wang, P., Van Roozendael, M., Clémer, K., and Irie, H.: Retrieving tropospheric nitrogen dioxide from the Ozone Monitoring Instrument: effects of aerosols, surface reflectance anisotropy, and vertical profile of nitrogen dioxide, Atmos. Chem. Phys., 14, 1441-1461, doi:10.5194/acp-14-1441-2014, 2014.