Detection from space of a reduction in anthropogenic emissions of nitrogen oxides during the Chinese economic downturn

Abstract:

Rapid economic and industrial development in
China and relatively weak emission controls have resulted in
significant increases in emissions of nitrogen oxides (NOx)
in recent years, with the exception of late 2008 to mid 2009
when the economic downturn led to emission reductions detectable
from space. Here vertical column densities (VCDs)
of tropospheric NO2 retrieved from satellite observations by
SCIAMACHY, GOME-2 and OMI (both by KNMI and by
NASA) are used to evaluate changes in emissions of NOx
from October 2004 to February 2010 identifying impacts of
the economic downturn. Data over polluted regions of Northern
East China suggest an increase of 27–33% in 12-month
mean VCD of NO2 prior to the downturn, consistent with an
increase of 49% in thermal power generation (TPG) reflecting
the economic growth. More detailed analysis is used to
quantify changes in emissions of NOx in January over the
period 2005–2010 when the effect of the downturn was most
evident. The GEOS-Chem model is employed to evaluate
the effect of changes in chemistry and meteorology on VCD
of NO2. This analysis indicates that emissions decreased by
20% from January 2008 to January 2009, close to the reduction
of 18% in TPG that occurred over the same interval. A
combination of three independent approaches indicates that
the economic downturn was responsible for a reduction in
emissions by 9–11% in January 2009 with an additional decrease
of 10%attributed to the slow-down in industrial activity
associated with the coincident celebration of the Chinese
New Year; errors in the estimate are most likely less than
3.4 %.

Notes:

Final Manuscript in DASH