Investigating the Link Between Glyoxal and Biogenic Activities - Towards an Interdisciplinary Approach in Earth System Science - page 54

Nevertheless, the uncertainties in total emissions are large due to their dependence
on several parameters, including condition and species of plants, humidity, and also
temperature (Guenther et al. 2000 ). Anthropogenic emissions are around 10 times
lower globally than biogenic emissions, while 50 TgCyr − 1 are emitted from
pyrogenic sources, however the uncertainties of estimation are high (Stavrakou
et al. 2009b ). In the last years, interest in the large variability of VOC fluxes into the

atmosphere led to investigation of the spatial and temporal distribution of molecules
such as formaldehyde (HCHO) and CHOCHO, because these are intermediate
products in the oxidation of most VOC. Moreover, CHOCHO is an indicator of
secondary aerosol formation (Fu et al. 2008 ; Sinreich et al. 2007 ; Vrekoussis et al.
2009 ) and has a short lifetime in the atmosphere, caused by photolysis (Tadi et al.
2006 ), and oxidation mechanisms in the presence of hydroxyl radicals (Setokuchi
2011 ). Additionally, wet and dry deposition are sinks of CHOCHO in the atmo-
sphere (Fu et al. 2008 ). In recent years, a number of retrievals of global distribution
of CHOCHO from satellite measurements has been reported including the SCan-
ning Imaging spectroMeter Atmospheric CHartographY (Bovensmann et al. 1999 ;
Burrows et al. 1995 ), the second Global Ozone Monitoring Experiment (GOME-2)
(Callies et al. 2000 ), and OMI (Levelt et al. 2006 ) by using the DOAS method in
the visible spectral region (Alvarado et al. 2014 ; Kurosu et al. 2007 ; Lerot et al.
2010 ; Chan Miller et al. 2014 ; Vrekoussis et al. 2009 ; Vrekoussis et al. 2010 ;
Wittrock et al. 2006 ). In these studies, the largest amounts of CHOCHO were
observed over tropical and sub-tropical regions with a large spatial and temporal
variability, mainly as result of vegetation and

fl

fire emissions.
In this study, a short description of the CHOCHO retrieval approach applied to
OMI measurements, as well as an investigation of the link between glyoxal and
biogenic emissions during 2005

2012 are presented.

-

2 Glyoxal Retrieval

DOAS is frequently applied for the remote sensing of trace gases concentrations in
the troposphere and stratosphere. This technique allows the determination of
amounts of trace gases with narrow absorption bands in the ultraviolet and visible
spectral range. DOAS is based on the Beer-Lambert law in the atmosphere by
analyses the intensity of absorption bands (Platt and Stutz 2008 ),

"

Z ds X
i

I ðkÞ
I 0 ðkÞ ¼

exp q i ð s Þr i ðk ; s Þþq Ray ð s Þr Ray ðk ; s Þ

ð 1 Þ

þq Mie ð s Þr Mie ðk ; s Þþq Ring ð s Þr Ring ðk ; s Þ