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 a campaign denominated VASCO (Variabilité Atmosphérique intra-Saisonnière et Couplage Océanique) aimed to study the predictability of intraseasonal convective perturbations in the Indo-Pacific tropical area, the role of air-sea coupling in this intraseasonal variability and the physical origin of the intraseasonal sea surface temperature variability in the western Indian Ocean.
The ten balloons launched during the campaign were released during January and Febraury 2007, from the Mahé airport in Seychelles Islands.
Balloon launched on: 2/5/2007 at 10:27 utc
Launch site: Seychelles International Airport, Mahe
Balloon launched by: Centre National d'Etudes Spatiales (CNES)
Balloon manufacturer/size/composition: Super Pressure Balloon
Flight identification number: D33
End of flight (L for landing time, W for last contact, otherwise termination time): 2/26/2007 at 1:26 utc
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 21 d
Landing site: Bransfield Strait, Antarctica
Campaign: VASCO 2007
This balloon endured aloft 21 days and traveled 24.870 kilometers from Seychelles Islands to Antarctica. This was the longest flight for a boundary layer balloon since it's introduction in the decade of 1970. Until then, mean life time was merely 10 days and distance a few thousands kilometers.
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