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München 2004 – scientific programme

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UP: Umweltphysik

UP 4: Satelliten und Anwendungen I

UP 4.2: Fachvortrag

Monday, March 22, 2004, 14:30–14:45, HS 225

Estimating the lifetime of boundary layer NOx using GOME data — •Steffen Beirle1, U. Platt1, N. Spichtinger2, A. Stohl3, M. Wenig4, and T. Wagner11Institut für Umweltphysik Heidelberg — 2TUM München — 3University of Colorado, USA — 4NASA Goddard Space Flight Center, USA

Nitrogen oxides are important trace gases with impact on health, rain acidity and especially ozone production in the troposphere. NO2 is detectable from satellite platforms using differential optical absorption spectroscopy (DOAS). Tropospheric column densities can be retrieved by estimating and subtracting the stratospheric column.

The lifetime of boundary layer NOx depends on many factors like OH concentration, humidity, actinic flux or wind transport and is therefore highly variable (several hours up to some days). Satellite measurements have the potential to estimate mean lifetimes of boundary layer NOx for different regions and seasons. Here we present two new approaches:

First, we investigate the weekly cycle of NO2 in industrialized regions: Emissions are minimal on Sundays. This influences, depending on the lifetime, the Monday levels of NO2. Second, we compare modelled NO2 distributions for different lifetimes (using EDGAR emissions and the Lagrangian particle dispersion model FLEXPART) with the distributions actually measured by GOME, to find a most likely lifetime.

With these methods, for instance for Germany, we find the mean lifetime of boundary layer NOx to be 6 hours in summer and about 24 hours in winter.

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