Weekly cycle of NO2 by GOME measurements: a signature of anthropogenic sources S. Beirle1, U. Platt1, M. Wenig2, and T. Wagner1 1Institut für Umweltphysik, Universität Heidelberg, Germany 2NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
Abstract. Nitrogen oxides
(NO+NO2=NOx and reservoir species) are important trace gases in the troposphere
with impact on human health, atmospheric chemistry and climate. Besides natural sources (lightning, soil
emissions) and biomass burning, fossil fuel combustion is estimated to be responsible for
about 50% of the total production of NOx. Since human activity in industrialized countries
largely follows a seven-day cycle, fossil fuel combustion is expected to be reduced
during weekends. This "weekend effect" is well known from local, ground based
measurements, but has never been analysed on a global scale before.
The Global Ozone Monitoring Experiment (GOME) on board the ESA-satellite ERS-2 allows
measurements of NO2 column densities. By estimating and subtracting the stratospheric column,
and considering radiative transfer, vertical column densities (VCD) of tropospheric
NO2 can be determined (e.g. Leue et al., 2001). We demonstrate the statistical
analysis of weekly cycles of tropospheric NO2 VCDs for different regions of the world. In the
cycles of the industrialized regions and cities in the US, Europe and Japan a clear Sunday
minimum of tropospheric NO2 VCD can be seen. Sunday NO2 VCDs are about
25-50% lower than working day levels. Metropolitan areas with other religious and cultural backgrounds
(Jerusalem, Mecca) show different weekly patterns corresponding to different days of rest. In
China, no weekly pattern can be found.
The presence of a weekly cycle in the measured tropospheric NO2 VCD may help to identify the different
anthropogenic source categories. Furthermore, we estimated the lifetime of tropospheric
NO2 by analysing the mean weekly cycle exemplarily over Germany, obtaining a value of about
6 h in summer and 18-24 h in winter.
Citation: Beirle, S., Platt, U., Wenig, M., and Wagner, T.: Weekly cycle of NO2 by GOME measurements: a signature of anthropogenic sources, Atmos. Chem. Phys., 3, 2225-2232, doi:10.5194/acp-3-2225-2003, 2003.