Purpose of the flight and payload description
The Boundary Layer Pressurized Balloons are closed aerostats that keep a nearly constant volume and therefore fly at a quasi-constant density level, acting as Lagrangian tracers of air parcels and meteorological platforms.
The balloon is fabricated by ZODIAC under CNES supervision. It's made of three-laminated polyester of 125 micrometers, has a 2.5m diameter spherical shape and a total mass of approximately 9 kg. This vehicle can fly in layers between the surface and approximately 830 hPa depending of its ballast. As long as a sufficient overpressure is maintained the volume remains constant, except for slight thermal fluctuations producing low amplitude buoyancy oscillations mostly driven by the diurnal cycle.
Scientific instrumentation on board the balloon consists in air pressure, temperature and humidity sensors, and a 3D location GPS receiver. Helium temperature and pressure are also recorded. Data is broadcasted with a mean 15 minutes period, through the ARGOS system. Power is provided by lithium batteries that ensure a mean lifetime of near one month. Batteries, electronics, ARGOS and GPS antenna are all located inside the envelope protected from the salty water when the balloon hits or gets close to the sea surface.
This flight was part of the AMMA (African Monsoon Multidisciplinary Analysis) campaign, an international project to improve the knowledge and understanding of the so called West African monsoon (WAM) and its variability with an emphasis on daily-to-interannual timescales. The effort was motivated by an interest in fundamental scientific issues and by the societal need for improved prediction of the WAM and its impacts on West African nations.
For AMMA a total of 15 balloons were launched during June 2006 from the Cotonou International Airport, in the Republic of Benin.
Details of the balloon flight
Balloon launched on: 7/9/2006 at 9:48 utc
Launch site: Cotonou Cadjehoun Airport, Benin
Balloon launched by: Centre National d'Etudes Spatiales (CNES)
Balloon manufacturer/size/composition: Super Pressure Balloon Zodiac 2.5 mts (Trilaminated Poliethylene - 125 microns)
End of flight (L for landing time, W for last contact, otherwise termination time): 7/13/2006
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 4 d 4 h
Campaign: AMMA (African Monsoon Multidisciplinary Analysis)