The primary objective of the European eXport of Precursors and Ozone by long-Range Transport (EXPORT) project is to characterise and quantify the photochemical air pollution both forming over Europe and being exported eastwards from Europe. The data held at BADC was collected during a co-ordinated 3 aircraft flying campaign in August 2000 based at Oberpfaffenhofen in Southern Germany. Measurements were made of many photochemical parameters including ozone, its precursors, other oxidants and both gas phase and particulate tracers in the air over Europe and that being transported eastwards out of Europe.

This dataset contains airborne atmospheric and chemistry measurements taken on board the Met Office C-130 Hercules aircraft flight A775 for the EXPORT project. The flight was over Germany, Austria, Czech and Slovak Reps, and Poland.

Study of PBL Air over Czech Republic and southern Poland contrasted with Uplifted (N. American) air at ca. 25,000ft

The aim of the experiment was to observe two areas of polluted air, as forecast by RDF trajectory forecasts and the NILU model. The first area was forecast to be over the Czech Republic / southern Poland at low levels and the second was forecast to be over southern Poland / Germany at higher altitudes (ca. 26,000 to 29,000ft. Both the Mystere and Falcon aircraft only planned to sample the higher altitude polluted layer. The results from the Mystere were planned to feed back to the C-130, after sampling the low level air. Indeed communications from the Mystere were passed to the C-130 but probably made little difference to the eventual plan.

The flight was very interesting. The main science started with a profile into an airfield at Ostrava, Czech Republic. Bottles were filled during the descent into the airfield. These should show 'chemical age' difference above and below the boundary layer. Below the inversion at around FL045, a rather heavily polluted boundary layer was sampled in the Czech Republic / southern Poland. Several runs were carried out in this air, mostly at an altitude of approximately 3,000ft above ground. The flight area was mostly very heavily polluted, with several factory chimneys and at least one power station that was passed several times. Once above a more rural area the levels of primary pollutants dropped significantly, possibly indicating that a significant fraction of the primary pollutant concentrations were due to the local sources. The aircraft remained in the PBL for quite some time. This was partly due to the requests of the mission scientists but also because of having to wait to go into Polish airspace.

The second part of the flight was at higher level, between ca. 26,000 and 29,000ft, in order to sample uplifted air forecast to be of N. American origin. The air was certainly rich in CO (up to around 100ppb) but interestingly the ozone was anti-correlated with the CO. It is possible that the air had been uplifted in convection, in which case the ozone concentration might be anti-correlated with the CO, if there has been insufficient time for photochemical processing. Alternatively, boundary layer air (from either N. America or Europe) may have mixed with dry, ozone-rich UTLS air.

Most instruments performed well, the exception being the PSAP, which was very noisy. The NOxy worked well but reported loss of flow into the NOy1 inlet (NOy minus HNO3), above ca. FL240.

Meteorology

The surface chart showed a weak ridge of high pressure over central Europe. The midday analysis showed a frontal feature stretching from the North Sea, across NE Germany and into Southern Poland. Some troughing of the upper air.