Stratéole-2: what observations for these new stratospheric balloons released in November?

© CNES / GABORIAUD Roman, 2018

CNES and a consortium of CNRS laboratories kicked off the Stratéole-2 program. Stratospheric balloons will be sent from Seychelles, to study the climatic phenomena of the zones situated between the two tropics.

The new mission follows the one carried out in 2005, in the Antarctic, which bore the name of Stratéole. This program is the result of a collaboration between several countries, including the United States, Italy, and France. Within France, several bodies have worked together, including the National Center for Space Studies (CNES) and several laboratories of the National Center for Scientific Research (CNRS).

A first balloon already dropped

The Stratéole-2 program is based on large stratospheric pressurized balloons with a diameter of 11 to 13 m. They carry about 22 kg of payload, including scientific instruments to perform various measurements and observations.

They will fly over the Earth, at an altitude between 18 and 20 km. The launch site was selected to optimize the duration of flights, while optimally covering the intertropical zone, which is the heart of the study. Thus, it is the airport of Mahé, the biggest island of the archipelago of Seychelles, which was chosen.

A first "blank" release, that is to say without scientific instrumentation, was made last Friday, and another of the same type is planned in the coming days. The purpose of these operations is to ensure the proper handling of the balloons during their flight, before proceeding to actual launches, the first being scheduled between 17 and 30 November 2019.

Study factors that play a role in the climate

Stratéole-2 is part of an initiative of the World Meteorological Organization, which aims to determine the influence of stratospheric processes on climate. More specifically, the CNES program aims to "  study the dynamics of the atmosphere in the intertropical zone  ".

Concretely, balloons will be particularly interested in two phenomena. First, they will be responsible for facilitating the analysis of transport mechanisms in the stratosphere of water vapor, which is the main greenhouse gas. Secondly, their measurements will make it possible to study the changes in the direction of the winds of altitude. Their observations may also contribute to the preparation of weather forecasts.

Each balloon will travel twice around the Earth in three or four months, depending on the wind. During this time, they will fly over 96 countries.

Source: CNRS