CNES PRESS RELEASE

PARIS, 7 October 2004

MEGHA-TROPIQUES
TAKING A CLOSER LOOK AT TROPICAL CLIMATE AND CYCLONES

Today, the CNES Board of Directors has given the go-ahead for phases C, D and E of the Megha-Tropiques project. This joint French-Indian mission is designed to study atmospheric circulation and the water cycle in the tropical belt. Data from the satellite will help to improve our understanding of the role played by the water cycle in the tropical atmospheric and tell us more about tropical convection processes. Megha-Tropiques is a component of the international Global Energy and Water cycle EXperiment (GEWEX) to study energy and water exchanges in the Earth/atmosphere system.

Circling Earth on a low-inclined orbit (20°), Megha-Tropiques—megha is the Sanskrit word for clouds and tropiques the French word for tropics—will study the water cycle and energy exchanges in the Earth/atmosphere system inside the Intertropical Convergence Zone (ITCZ) at different temporal and spatial scales. The ITCZ is where forcing of the atmosphere by solar radiation is strongest, this energy being partly stored as latent heat of evaporation in the oceans. This energy is then redistributed in the atmosphere through condensation and precipitation. The role of water in the tropical atmosphere is a complex phenomenon and its effect on climate is still poorly understood. And, within the wider perspective of climate change, the distribution of water vapour, cloud and radiative fluxes, and precipitations and latent heat are likely to be modified. Studying the energy budget throughout the ITCZ is therefore emerging as a priority for scientists researching the climate system and climate variations brought about by human activities.

Variations in energy and water budget exchanges in the land/ocean/atmosphere system in the Tropics have a major influence on climate all around the globe. These systems interact with the general atmospheric circulation in ways we still do not fully understand—one reason why weather forecasts and predictions of climatic events such as cyclones, monsoons, flooding and drought are not more accurate. The Megha-Tropiques mission will improve our understanding of these processes and better assimilate them in climate and meteorology models.

To fulfil these objectives, the Megha-Tropiques satellite will be carrying instruments such as : the MADRAS microwave imaging radiometer, the SAPHIR microwave sounder and the SCARAB radiometer.

Megha-Tropiques data are set to:
- give more accurate representations of humid convection and how it interacts with dynamics and radiation in large-scale models
- quantify the role of water vapour in the greenhouse effect
- enhance understanding of extreme events like floods and drought linked to the natural variability of the water cycle in the tropical belt and, ultimately, allow us to forecast them better
- improve knowledge and forecasting of tropical cyclones

Megha-Tropiques is slated to launch in 2008/2009 into an 867-kilometer orbit. The satellite’s data collection mission is scheduled to last three years.

First recommended by CNES’s science programmes committee (CPS) after the space science seminar in Saint Malo in 1993, then confirmed at the following seminar in Arcachon in 1998, Megha-Tropiques is a joint CNES/ISRO (Indian Space and Research Organization) initiative for which the partner agencies will share responsibility for mission and science aspects.

ISRO will have responsibility for the system and satellite, supported by CNES, and is also supplying the launch vehicle, spacecraft bus, satellite operations control centre, science data receiving station and mission centre. It is prime contractor for the MADRAS instrument.

CNES is supplying the microwave elements for the MADRAS imager (MARFEQ subassembly), which will be developed by EADS-Astrium. It is also prime contractor for the SAPHIR and SCARAB instruments, which it is developing in house with support from research laboratories at the Institut Pierre Simon Laplace: the LMD dynamic meteorology research laboratory; the CETP terrestrial and planetary environment research centre; and the LERMA (Astrophysical Radiation and Matter Research Laboratory) at the Observatoire de Paris.

Data processing, archiving and product distribution will be handled by the science data centre located In India while the French scientists will use the ICARE research structure set up in Lille, northern France, last year, by CNES, CNRS,Lille UNiversity and Conseil Regional Nord Pas de Calais for their research.

CNES’s financial contribution is 48 millions of euros.

ISRO Chairman, G. Madhavan Nair, said: "Megha Tropiques is an important mission which will provide vital atmospheric data over the tropical region that would help in monsoon variability studies. I am happy over the progress made in this programme".

CNES President Yannick d'Escatha said: “This decision demonstrates the importance CNES attaches to the stewardship of our planet and once again confirms the utility of space assets in improving our understanding of its underlying mechanisms. Megha-Tropiques is a fine and promising mission made possible by our successful long-term partnership with ISRO.”

Sandra LALY
Phone: +33 1 44 76 77 32
Mobile: +33 6 08 48 39 31