Ozonesonde activities

Several ozonesonde stations will be active during the THESEO 2000 campaign.

There will be regular launches at specific times and there will be a coordinated Lagrangian ozonesonde campaign (Match) aiming at measuring directly the chemically-induced ozone loss inside the polar vortex during the 1999-2000 winter. The Match campaign is coordinated by the Alfred Wegener Institute in Potsdam. The ozonesonde data are transferred to the NILU database NADIR in near real time. Data quality control is carried out by FMI in Sodankyla. Forecast trajectories are calculated by FU Berlin.

Ozonesonde launch in Ny-Ålesund at 79 degrees north.

Photo: Thomas Seiler

Description of the Match technique

Match is a Lagrangian experiment in the course of which ozone sounding at the Arctic and sub-Arctic ozone sonde station net will be coordinated. The experiment will commence by launching a so-called primary sonde at each participating station. Depending on trajectory calculations based on analysis and forecast meteorological fields of ECMWF, a second sonde (the matching sonde or secondary sonde) will be launched into the same air mass a few days later, usually from another station. Normally, the delay between such two soundings lies between 3 and 10 days. Any secondary sonde will further act automatically as a new primary sonde. During the offline analysis all trajectories will be recalculated using no longer forecast meteorological fields but using in addition cooling/heating rates determined from a GCM in order to improve quality. Each pair of ozone soundings connected through such a trajectory (a match) will be checked by several quality criteria. By combining in several time and space bins the ozone differences within the resulting matches in a statistical approach, ozone loss rates can be deduced in an appropiate resolution. Similar action will be performed for ozone lidar measurements. It is anticipated to calculate and to manage an ER-2 Match flight track based on the same principle. In such a case the whole data set of the ER-2 instruments would be used to create match trajectory sets with great chemical background instead of ozone only. This would result in a very valuable data set which would be relatively easily comparable to different model outputs. ER-2 is a stratospheric aircraft operated by NASA from Kiruna during SOLVE.

Click here to read interim report of 25 February on results of the Match campaign.

Explanation of Match technique. From Peter von der Gathen.

Map of the participating ozone sonde stations with a trajectory example connecting ozone sonde launches at Ny-Ålesund/Spitsbergen and Sodankylä/Finland.

This winter Match will concentrate mainly on soundings north of 60 degree north.

Click on the map to get it in full resolution.

Results of previous Match campaigns in different winters at about 20 km height. The upper panels denote the size of the area in that height of the stratosphere where the temperature is lower than the treshold temperature of polar stratospheric clouds (PSC type I: blue, PSC type II: dark blue). The lower panels denote the ozone loss rates as determined with the Match method.

Click on the image to see it in full resolution.