Ultimately HOOVER was not funded, but the project continues to pursue funding and would provide a valuable contribution to the field of atmospheric chemistry.

The campaigns include a set of north-south transects from Germany to northern Europe (Kiruna, 67°N) and southern Europe (Sardinia, 39°N). Some of the flights to Kiruna, especially during the upcoming campaign planned to take place in April-May 2008, are extended by additional flights into the Arctic. The aircraft is equipped with a set of instruments measuring species relevant for photochemistry (HOx, NOx, O3, Peroxides, HCHO, N2O, CO, OVOC, VOC, H2O) and actinic flux.

Objectives :

- Latitudinal cross sections from southern to northern Europe to quantify the concentrations of pollutants (NOx, O3, VOC) and the oxidation capacity in the free troposphere.

- Seasonal variability and its impact on the pollutants and the oxidation capacity in the free troposphere.

- Ozone and HOx budget in the Arctic free troposphere.

- Chemical evolution and life time of pollutants.

- Comparison of the measurements with a box model to evaluate our understanding of the ozone and HOx budget and their seasonal variability.

- Comparison with 3D-GCM to evaluate the understanding of transport of pollutants and its influence on the arctic atmospheric chemistry.