München 2004 – wissenschaftliches Programm

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UP: Umweltphysik

UP 4: Satelliten und Anwendungen I

UP 4.2: Fachvortrag

Montag, 22. März 2004, 14:30–14:45, HS 225

Estimating the lifetime of boundary layer NO_x using GOME data — •Steffen Beirle¹, U. Platt¹, N. Spichtinger², A. Stohl³, M. Wenig⁴, and T. Wagner¹ — ¹Institut 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 NO_x 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 NO_x 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 NO_x to be 6 hours in summer and about 24 hours in winter.