The balloon launch site was chosen to provide the best possible coverage of the intertropical zone and to optimize flight duration. Mahé airport in The Seychelles, in the Indian Ocean, was identified as the site affording the best conditions. The balloons, spanning 11 to 13 metres and carrying payloads weighing around 22 kilograms, gain altitude and stabilize about one hour into their flight at a ceiling of 18 to 20 kilometres. Over the course of three to four months, borne by the winds, they will circumnavigate the planet twice and potentially overfly 96 countries as they collect their data.
The goal of these observations is to gain new insights into the climate mechanisms of the lower stratosphere at the equator, in particular those transporting the main greenhouse gas—water vapour—in the stratosphere and the periodic change in direction of stratospheric winds called the Quasi-Biennial Oscillation (QBO). Strateole-2 comes under the umbrella of the World Meteorological Organization’s SPARC programme (Stratosphere-troposphere Processes And their Role in Climate). Certain observations will be sent in near-real time to weather centres around the world to help improve forecasting. CNES has been a leading international operator of stratospheric balloons for many years now. It has conducted several successful missions since the Strateole-Vorcore campaign in the Antarctic in 2005 and developed the flight control systems for Strateole-2 to the highest safety and reliability standards.
This project initiated by France has attracted a broad panel of international partners, in particular the United States. In France, CNES is working with a number of research laboratories at CNRS and its other partners: the LMD dynamic meteorology research laboratory (CNRS/ENS Paris/Ecole Polytechnique/SU), the LATMOS atmospheres, environments and space observations laboratory (CNRS/UVSQ/SU), the LPC2E environmental and space physics and chemistry laboratory (CNES/CNRS/University of Orléans), the GSMA molecular and atmospheric spectrometry laboratory (CNRS/University of Reims Champagne-Ardenne) and CNRM, the national meteorological research centre (Meteo-France/CNRS). In Italy, it is teamed with the Instituto di Scienze dell'Atmosfera e del Clima (CNR-ISAC), and in the United States with the Laboratory for Atmospheric and Space Physics (LASP, University of Colorado), Northwest Research Associates and Scripps Institution of Oceanography.