Measured and modeled trends of stratospheric Cly and Fy column amounts in the northern hemisphere

The german HGF virtual institute PEP (Pole-Equator-Pole) has been established in
2004 in order to investigate the variability of atmospheric trace constituents along a
north-south transection. Within PEP the HGF centres AWI and FZK as well as the
german Universities of Bremen, Karlsruhe and Potsdam combine their knowledge
and capabilities in ground-based measurements and global and regional modelling
of atmospheric trace constituents and aerosols.
Here we present results of long-term measurements of the stratospheric column of
HCl, ClONO2, HF, and O3 obtained at the different PEP stations in the northern
hemisphere and in addtion at Jungfraujoch. All stations are affiliated
to the NDACC (Network for the Detection of Atmospheric Composition Change).
The measured time series are compared with long-term model calculations
performed with a state of the art 2-D model of the University of Bremen and the 3-D
CTM KASIMA. Please note, that the lowest altitude for the determination of the total
columns is about 7 km leading to a slight underestimation w.r.t. the measurements.