Andre Vargas

The Concordiasi Field Experiment over Antarctica: First results from innovative atmospheric measurements

Florence Rabier , Steve Cohn , Philippe Cocquerez , Albert Hertzog, Linnea Avallone, Terry Deshler, Jennifer Haase , Terry Hock, Alexis Doerenbecher , Junhong Wang , Vincent Guidard, Jean-Noël Thépaut , Rolf Langland, Andrew Tangborn , Gianpaolo Balsamo , Eric Brun, David Parsons , Jérôme Bordereau , Carla Cardinali , François Danis , Jean-Pierre Escarnot , Nadia Fourrié, Ron Gelaro, Christophe Genthon , Kayo Ide, Lars Kalnajs, Charlie Martin, LouisFrançois Meunier , Jean-Marc Nicot , Tuuli Perttula, Nicholas Potts , Patrick Ragazzo , David Richardson, Sergio Sosa-Sesma , André Vargas 3

THE AEROCLIPPER A New Device to Explore Convective Systems and Cyclones

Aeroclipper balloons, designed for taking measurements at the air-sea interface, can withstand extreme conditions encountered when they are drawn into tropical cyclones and then follow the eye trajectory.

Driftsondes: Providing In Situ Long-Duration Dropsonde Observations over Remote Regions

Constellations of driftsonde systems— gondolas floating in the stratosphere and able to release dropsondes upon command— have so far been used in three major field experiments from 2006 through 2010. With them, high-quality, high-resolution, in situ atmospheric profiles were made over extended periods in regions that are otherwise very difficult to observe. The measurements have unique value for verifying and evaluating numerical weather prediction models and global data assimilation systems; they can be a valuable resource to validate data from remote sensing instruments, especially on satellites, but also airborne or ground-based remote sensors. These applications for models and remote sensors result in a powerful combination for improving data assimilation systems. Driftsondes also can support process studies in otherwise difficult locations—for example, to study factors that control the development or decay of a tropical disturbance, or to investigate the lower boundary layer over the interior Antarct...

Low-Atmosphere Drifting Balloons: Platforms for Environment Monitoring and Forecast Improvement

AbstractBalloons are one of the key observing platforms for the atmosphere. Radiosounding is the most commonly used technique and provides over a thousand vertical profiles worldwide every day. These data represent an essential cornerstone of data assimilation for numerical weather prediction systems. Although less common (but equally interesting for the in situ investigation of the atmosphere), drifting boundary layer pressurized balloons (BLPBs) offer rare observational skills. These balloons collect meteorological and/or chemical measurements at isopycnal height as they drift in a quasi-Lagrangian way. The BLPB system presented in this paper was developed by the French Space Agency [Centre National d’Etudes Spatiales (CNES)] and has been used in field experiments focusing on precipitation in Africa [African Monsoon Multiscale Analysis (AMMA)] and the Mediterranean [Hydrological Cycle in the Mediterranean Experiment (HyMeX)] as well as on air pollution in India [Indian Ocean Experiment (INDOEX)] and the...

Returning to Hydrogen Gas : a Strategic Decision to Continue Achievement of Stratospheric Balloons Flights

The Balloons Sub-directorate of the French Space Agency (CNES) has developed and operated a wide range of balloon vehicles which include Zero-pressure Stratospheric Balloons (BSO) since the early 1960’s, for the national and international scientific community. Until winter 1999/2000, the BSO main envelope was inflated with hydrogen gas. The use of this gas for balloon inflation also included transport and storage issues, and was then part of the operational team expertise. By 2000, helium gas had been chosen to replace hydrogen gas for the main envelop inflation for safety reasons. Indeed helium has some advantages (inert gas, safety handling), but also presents some drawbacks:  Nonrenewable resource.  Expensive to extract.  Supply difficulties (few storage sites).  Increasing cost, due to constant growth of industrial and scientific applications combined with the decrease of the supply of the world market, are now becoming alarming for CNES Balloons program sustainability. Compared to helium, hydrogen gas is produced from primary sources (natural gas, hydrocarbons or biomass), which ensures the energy source sustainability and consequently, there are many storage places, closer to our various launching sites, lowering the transport cost to an acceptable level. In addition, taken into account balloon performances, hydrogen as gas inflation allows a 7% decrease in the required gas volume to raise a load and the balloon rises faster and higher. The only “dark” side of hydrogen gas is related to its high flammability properties. A working group has been mandated by the Director of the Toulouse Space Center, in order to gather information to make a decision about the replacement. The group has raised questions, particularly related to safety. A hazard study was carried out by experts of the National Industrial Environment and Risks Institute (INERIS). Potential accidental events (ERC) have been highlighted in the implementation and the operability of a BSO for each of the phases of a flight (negative countdown during ground operations, ascending to ceiling, flight, flight ending and recovery). This paper presents the results of the hazard study with its impacts on the modification of the hardware (ground and flight segments), as well as the impact on the operations for the preparation and the release of the balloon.