Abstract :
[en] Reactive inorganic chlorine plays a crucial role in the stratospheric ozone depletion.
To stabilize and enable a recovering of the stratospheric ozone layer, the Montreal
protocol and its amendments and adjustments have been progressively implemented to
reduce or even stop the production and emission of important chlorinated source gases
(CFCs, HCFCs, CCl4, CH3CCl3, and Halons). As these source gases are photolysed in
the stratosphere into inorganic chlorine and fluorine, respectively, the turn over of the
inorganic chlorine (HCl and ClONO2) and slowing down of fluorine (HF and COF2)
reservoirs act as a verification of the effectiveness of these protocols.
Here we present results of long-term measurements of the stratospheric column of
HCl, ClONO2, and HF obtained at different stations in the northern hemisphere (Ny
Alesund, Kiruna, Zugspitze, Jungfraujoch, Izana, all affiliated to the NDACC, Network
for the Detection of Atmospheric Composition Change) within the PEP (Pole-
Equator-Pole) network. These time series are interpreted with model calculations performed
with a state of the art 2-D model and the 3-D CTM KASIMA with respect
to the determination of the slowing down or turn over, respectively. In addition, trend
parameters calculated using different approaches (e.g. linear trend, bootstrap-method)
will be presented and intercompared.
