BALSAMINE Campaign (1979)
BALSAMINE (BALlons Surpressurises pour l'Analyse de la Mousson INdienne d'Ete) was a superpressure balloon launch campaign carried out in 1979 in the Indian Ocean, which was originally proposed by two scientists of the Laboratoire de Meteorologie Dynamique (LMD): Daniel Cadet and Gilles Sommeria.
BALSAMINE was sponsored by the Centre National d'Etudes Spatiales (CNES) and the Delgation Generale de la Recherche Scientifique et TechniqUe (DGRST) and was the French contribution to the Summer MONEX (Monsoon Experiment), a GARP (Global Atmospheric Research Program) subprogram, which was implemented to collect a large data set on the Indian Summer monsoon and to improve the knowledge on various related meteorological problems in the region.
The preparation of the campaign started on June 1978. A fundamental change from previous operations with similar balloons was the adoption by CNES of the newly introduced ARGOS location system instead of the NIMBUS platform being used. Although the new system allowed "quasi" realtime tracking of the balloons, it weighted considerably more than its predecessor, hence forcing to increase the balloon size. Thus, the BALSAMINE platform was finally based on a non-extensible polyester 2.5 m diameter balloon envelope. The electronic equipment, except for the ambient sensors and the antenna, was placed inside the envelope of the balloon to protect them from the waves and rain buffeting in case the balloon could descend due to icing to the sea. This allowed the balloon to recover its nominal buoyancy after drying out. As a complementary measure wax was also sprayed on the envelope of the balloon, to reduce water retention.
A polyesthirene container attached to the lower pole of the balloon housed the power supply (lithium cells), the transmitter-oscillator, data encoder, and a pressure transducer to measure the pressure inside the envelope. The 400 mhz Argos antenna, a second pressure transducer to measure the air pressure, and their associated electronics were fastened to the upper pole of the balloon. Finally, the remaining two temperature sensors and the humidity sensor were located hanging at the end of three 80 cm long sticks fastened on the envelope of the balloon. The total weight of the equipment was in the order of the 3.5 kg.
The operations were based in two sites Mahe, in the Seychelles Islands and Diego Suarez in the northern tip of Madagascar.
The launch strategy devised was to release an average of two balloons per day from Seychelles and one or two from Madagascar during the onset of the monsoon, which occurs mainly at the end of May or begining of June. Nevertheless, that year the onset of monsoon was delayed so the first balloons aloft were carried to the African continent instead to the Indian Ocean. There, many disappeared sucked by the intertropical convergence zone, so the LMD scientists were forced to stop the launches in May 25. Finally the onset of the monsoon occured on the last days of June when the balloon launches were resumed.
The new Argos system allowed for the first time the access to location information and measurements of the balloons via the ARGOS server at CNES in Toulouse. Using a telephone handset and an acoustic modem connected to a thermal printer the scientists on the field were capable to recover position and information for each balloon in flight. Even after some manual processing, the data was returned by telex daily to the launching teams, which allowed them to follow the status of the balloons.
During the near three months of field operations (May 15 to July 8) a total of 88 superpressure constant-level balloons were launched: 60 balloons from Seychelles and 28 from Diego Suarez.
List of the balloons launched during the BALSAMINE campaign (incomplete)