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Stephen A. Cohn, Terry Hock, Philippe Cocquerez, Junhong Wang, Florence Rabier, David Parsons, Patrick Harr, Chun-Chieh Wu, Philippe Drobinski, Fatima Karbou, Stéphanie Vénel, André Vargas, Nadia Fourrié, Nathalie Saint-Ramond, Vincent Guidard, Alexis Doerenbecher, Huang-Hsiung Hsu, Po-Hsiung Lin, Ming-Dah Chou, Jean-Luc Redelsperger, Charlie Martin, Jack Fox, Nick Potts, Kathryn Young, and Hal Cole

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 Antarctic continent. The driftsonde system is now a mature and robust observing system that can be combined with flight-level data to conduct multidisciplinary research at heights well above that reached by current research aircraft. In this article we describe the development and capabilities of the driftsonde system, the exemplary science resulting from its use to date, and some future applications.

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Florence Rabier, Aurélie Bouchard, Eric Brun, Alexis Doerenbecher, Stéphanie Guedj, Vincent Guidard, Fatima Karbou, Vincent-Henri Peuch, Laaziz El Amraoui, Dominique Puech, Christophe Genthon, Ghislain Picard, Michael Town, Albert Hertzog, François Vial, Philippe Cocquerez, Stephen A. Cohn, Terry Hock, Jack Fox, Hal Cole, David Parsons, Jordan Powers, Keith Romberg, Joseph VanAndel, Terry Deshler, Jennifer Mercer, Jennifer S. Haase, Linnea Avallone, Lars Kalnajs, C. Roberto Mechoso, Andrew Tangborn, Andrea Pellegrini, Yves Frenot, Jean-Noël Thépaut, Anthony McNally, Gianpaolo Balsamo, and Peter Steinle

The Concordiasi project is making innovative observations of the atmosphere above Antarctica. The most important goals of the Concordiasi are as follows:

  • To enhance the accuracy of weather prediction and climate records in Antarctica through the assimilation of in situ and satellite data, with an emphasis on data provided by hyperspectral infrared sounders. The focus is on clouds, precipitation, and the mass budget of the ice sheets. The improvements in dynamical model analyses and forecasts will be used in chemical-transport models that describe the links between the polar vortex dynamics and ozone depletion, and to advance the under understanding of the Earth system by examining the interactions between Antarctica and lower latitudes.

  • To improve our understanding of microphysical and dynamical processes controlling the polar ozone, by providing the first quasi-Lagrangian observations of stratospheric ozone and particles, in addition to an improved characterization of the 3D polar vortex dynamics. Techniques for assimilating these Lagrangian observations are being developed.

A major Concordiasi component is a field experiment during the austral springs of 2008–10. The field activities in 2010 are based on a constellation of up to 18 long-duration stratospheric super-pressure balloons (SPBs) deployed from the McMurdo station. Six of these balloons will carry GPS receivers and in situ instruments measuring temperature, pressure, ozone, and particles. Twelve of the balloons will release dropsondes on demand for measuring atmospheric parameters. Lastly, radiosounding measurements are collected at various sites, including the Concordia station.

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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, Louis-François Meunier, Jean-Marc Nicot, Tuuli Perttula, Nicholas Potts, Patrick Ragazzo, David Richardson, Sergio Sosa-Sesma, and André Vargas
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Véronique Ducrocq, Isabelle Braud, Silvio Davolio, Rossella Ferretti, Cyrille Flamant, Agustin Jansa, Norbert Kalthoff, Evelyne Richard, Isabelle Taupier-Letage, Pierre-Alain Ayral, Sophie Belamari, Alexis Berne, Marco Borga, Brice Boudevillain, Olivier Bock, Jean-Luc Boichard, Marie-Noëlle Bouin, Olivier Bousquet, Christophe Bouvier, Jacopo Chiggiato, Domenico Cimini, Ulrich Corsmeier, Laurent Coppola, Philippe Cocquerez, Eric Defer, Julien Delanoë, Paolo Di Girolamo, Alexis Doerenbecher, Philippe Drobinski, Yann Dufournet, Nadia Fourrié, Jonathan J. Gourley, Laurent Labatut, Dominique Lambert, Jérôme Le Coz, Frank S. Marzano, Gilles Molinié, Andrea Montani, Guillaume Nord, Mathieu Nuret, Karim Ramage, William Rison, Odile Roussot, Frédérique Said, Alfons Schwarzenboeck, Pierre Testor, Joël Van Baelen, Béatrice Vincendon, Montserrat Aran, and Jorge Tamayo

The Mediterranean region is frequently affected by heavy precipitation events associated with flash floods, landslides, and mudslides that cause hundreds of millions of euros in damages per year and, often, casualties. A major field campaign was devoted to heavy precipitation and f lash f loods from 5 September to 6 November 2012 within the framework of the 10-yr international Hydrological Cycle in the Mediterranean Experiment (HyMeX) dedicated to the hydrological cycle and related high-impact events. The 2-month field campaign took place over the northwestern Mediterranean Sea and its surrounding coastal regions in France, Italy, and Spain. The observation strategy of the field experiment was devised to improve knowledge of the following key components leading to heavy precipitation and flash flooding in the region: 1) the marine atmospheric f lows that transport moist and conditionally unstable air toward the coasts, 2) the Mediterranean Sea acting as a moisture and energy source, 3) the dynamics and microphysics of the convective systems producing heavy precipitation, and 4) the hydrological processes during flash floods. This article provides the rationale for developing this first HyMeX field experiment and an overview of its design and execution. Highlights of some intensive observation periods illustrate the potential of the unique datasets collected for process understanding, model improvement, and data assimilation.

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