Impact of tropospheric nitrogen dioxide on the regional radiation budget 1Science Systems and Applications Inc., Lanham, MD, USA
2Goddard Space Flight Center, Greenbelt, MD, USA
3Royal Netherlands Meteorological Institute (KNMI), de Bilt, The Netherlands
4SRI International, Menlo Park, CA, USA
5University of Maryland, Baltimore County, USA
6RT Solutions, Cambridge, MA, USA
Received: 11 Mar 2009 – Published in Atmos. Chem. Phys. Discuss.: 03 Jun 2009 Abstract. Following the launch of several satellite ultraviolet and visible
spectrometers including the Ozone Monitoring Instrument (OMI), much
has been learned about the global distribution of nitrogen dioxide
(NO2). NO2, which is mostly anthropogenic in origin, absorbs solar
radiation at ultraviolet and visible wavelengths.
We parameterized NO2 absorption for fast radiative
transfer calculations. Using this parameterization with cloud, surface, and
NO2 information from different sensors in the NASA A-train constellation
of satellites and NO2 profiles from the Global Modeling Initiative (GMI), we
compute the global distribution of net atmospheric heating (NAH) due to
tropospheric NO2 for January and July 2005. The globally-averaged NAH
values due to tropospheric NO2 are very low: they are about 0.05 W/m2.
While the impact of
NO2 on the global radiative forcing is small, locally it can produce
instantaneous net atmospheric heating of 2–4 W/m2 in heavily polluted areas.
We assess the impact of clouds and find that they reduce the globally-averaged NAH
values by 5–6% only. However,
because most of NO2 is contained in the boundary layer in
polluted regions, the cloud shielding effect can significantly reduce the net
atmospheric heating due to tropospheric NO2 (up to 50%). We examine
the effect of diurnal variations
in NO2 emissions and chemistry on net atmospheric heating and find only a
small impact of these on the daily-averaged heating (11–14% at the most).
We also examine the sensitivity of NO2 absorption to various geophysical
conditions. Effects of the vertical distributions of cloud optical depth and
NO2 on net atmospheric heating and downwelling radiance are simulated in
detail for various scenarios including vertically-inhomogeneous convective
clouds observed by CloudSat. The maximum effect of NO2 on downwelling
radiance occurs when the NO2 is located in the middle part of the cloud
where the optical extinction peaks.
Revised: 21 Aug 2009 – Accepted: 24 Aug 2009 – Published: 04 Sep 2009
Citation: Vasilkov, A. P., Joiner, J., Oreopoulos, L., Gleason, J. F., Veefkind, P., Bucsela, E., Celarier, E. A., Spurr, R. J. D., and Platnick, S.: Impact of tropospheric nitrogen dioxide on the regional radiation budget, Atmos. Chem. Phys., 9, 6389-6400, doi:10.5194/acp-9-6389-2009, 2009.