The Aeroclipper: A new device to explore convective systems and cyclones

The Aeroclipper device is a balloon that carries an instrumented guide rope. It freely moves with the surface wind on quasi-Lagrangian trajectories, performing measurements in the atmospheric surface layer and at the Ocean surface. The Aeroclipper was primarily designed to measure low level dynamics and surface turbulent fluxes perturbations produced by organized deep convection over the tropical Oceans. These balloons are attracted toward convective regions by the low-level wind convergence generated by the associated low surface pressure. Compared to Eulerian platforms (moored buoys) or to oceanographic ships, these balloons are thus expected to optimize the measurement statistics in the vicinity and under active convective systems.

During the Vasco (Validation of the Aeroclipper System under Convective Occurrences) test experiment, in January and February 2007, six Aeroclipper prototypes were launched from the Mahé Island in the tropical Indian Ocean. Two of these Aeroclippers survived in the tropical cyclone Dora, enduring wind speed larger than 40ms-1 and giving continuous estimates of the tangential and the radial winds as a function of the eye distance. The two Aeroclippers then stayed confined into the eye of Dora for more than a week and remained captured in the low-pressure center when Dora became an extra-tropical depression.

The initial scientific objectives, the Aeroclipper instrumentation and some preliminary results of the Vasco test experiment will be presented. Extensions of the scientific objectives of the Aeroclipper device for Tropical Cyclone issues will be also discussed.