POLSTAR

POLSTAR in ’98

Airborne expedition to investigate the causes of ozone loss in the region of the Polar Tropopause

The measurement campaign POLSTAR 98 took place in January – February 1998 in Kiruna, northern Sweden, as part of the Ozone Research Programme of the Federal Ministry for Education, Science, Research and Technology (BMBF).

The main aim of the „Polar Stratospheric Aerosol Experiment“ POLSTAR was to investigate the formation and composition of the cirrus clouds that form in the region of the upper troposphere and lower Stratosphere. It is suspected that these ice clouds, or the chemical processes which occur on the surface of the aerosol particles, play an important role in the destruction of ozone.

Two research aircraft based in Kiruna were used for the measurement of particles and trace gases during the experiment. A total of eight flights were made during the three weeks of the experiment. Most of the flights involved both aircraft flying in tight formation so as to allow simultaneous measurements using a complex combination of measurement systems.

The Learjet 35A D-CGFD was operated as a research aircraft for the first time as part of a cooperation venture between the companies GFD and enviscope. The second aircraft involved was the Falcon D-CMET from the DLR.

The following measurement systems were installed on the Learjet 35A, D-CGFD:

Measurement systems and the operating Groups:
Description Institute PI
VACA/AAMAS * MPI-K Heidelberg Frank Arnold
Ion-Trap * MPI-K Heidelberg Frank Arnold
FSSP 300 IPA University of Mainz Stephan Borrmann
HACOPAC IPA University of Mainz Volker Dreiling
O3 MPI-C Mainz Horst Fischer
FISH FZ Jülich Cornelius Schiller
Basic Meteorology enviscope GmbH Dieter Schell
* flown alternately

where:

VACA/ AAMAS = „Automatic Aircraft-borne Mass Spectrometer“ with prior „Volatile Aerosol Composition Analyzer“ (Ion-Molecule-Reaction Mass Spectrometer with a prior evaporation stage for the determination of the composition of the volatile aerosol components, especially H2SO4 and HNO3);
Ion-Trap = Ion-trap mass spectrometer for the determination of gaseous trace compounds;
FSSP 300 =“Forward Scattering Spectrometer Probe“ for the determination of the size distribution of cloud particles in the size range > 0.41 µm;
HACOPAC =“High Altitude Condensation Optical Particle Aerosol Counters“ for the determination of the size distribution of atmospheric aerosol in the size range from 10 nm to approx. 5 µm;
O3 = Ozone analyser;
FISH = „Fast In-Situ Stratospheric Hygrometer“ for determination of the water vapour content.

All systems were operated for the first time on the Learjet 35A. The systems operated without technical problems on all of the eight flights, despite the extreme winter conditions experienced on some flights.

The individual flights lasted up to 4.5 hours, so that it was possible to make flights to the area around Spitzbergen without the necessity of landing for refuelling. During the flights, the Learjet was able to make measurements at its maximum flight altitude of 45000 ft.