Test flights of CNES stratospheric superpressure balloons in experimental arctic campaigns 2000-2001 objectives and results

Superpressure balloons float at constant air density levels for duration exceeding 2 months. One scientific use is to study the dynamics of air parcels, using the quasi Lagrangian property of their trajectories. CNES started in 1995 the development of such balloons for low stratosphere : the "STRATEOLE" project, whose principal investigator was the Laboratoire de Meteorologie Dynamique. The purpose was the study of the dynamics of the dilution process of the winter polar vortex over Antarctic. The initial design of the balloons and related systems, done by extrapolation of existing small tropospheric balloons, did show a poor reliability for use at low latitude and an incompatibility with Arctic conditions. In 1999, CNES redesigned the balloons and associated systems, with innovative solutions. Today the validation process of the new design is well advanced, in particular 15 short duration flights and 3 long duration flights have been conducted in winter and spring from the Arctic base of Esrange (Sweden). The results, although still partial due to the exceptionally warm conditions experienced this year in the low stratosphere over Arctic are very positive and allow to restart the preparation of the VORCORE campaign over Antarctic in fall 2003.