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 0.05W/m2.
While the impact of NO2 on the global radiative forcing is
small, locally it can produce instantaneous net atmospheric
heating of 2–4W/m2 in heavily polluted areas. We assess
the impact of clouds and find that they reduce the globallyaveraged
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 distri-
butions 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.