Bremen 2000 – scientific programme

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UP: Umweltphysik

UP 16: Poster: Modellierung (Atmosph
äre)

UP 16.3: Poster

Friday, March 24, 2000, 10:45–11:45, Foyer

Measurement and Modelling of Nitrate Radical Slant Columns in High- and Midlatitudes — •Silvia Schlieter, Marco Bruns, Richard Müller, Andreas Richter, Folkard Wittrock, and John P. Burrows — Institute of Environmental Physics, University of Bremen, Kufsteiner Strasse, 28359 Bremen, Germany

In high latitudes the nitrate radical (NO₃) plays an important role in the denitrification process of the polar stratosphere. Besides ozone and the hydroxyl radical (OH) the nitrate radical is another oxidant in the atmosphere with high abundances during night, when OH concentrations are low.

Measurements were performed inside the polar vortex with low stratospheric temperatures and during a sudden stratospheric warming when the temperatures of the upper stratosphere increased rapidly. Very high NO₃ slant columns were measured according to the strong temperature dependence of the production reactions.

For modelling the slant columns the model package BRAPHO/SLACO is used and shows good agreement with the measured course of the nitrate radical.

Because of the oxidation capacity of NO₃ tropospheric concentrations are estimated from measurements at midlatitudes with the contributions of stratospheric NO₃ are calculated by the model. As expected they are showing high variability and amounts in urban areas.