Tristan L'Ecuyer, professeur à l'Université du Wisconsin à Madison (USA) et expert en observation de la pluie et des nuages pour l'étude du système climatique, viendra au LATMOS / Guyancourt  le

    vendredi 21 septembre à 11h, salle 2202et donnera un séminaire intitulé

A Quest to Fill a Startling Gap in Observing Arctic Climate

Far-infrared radiation (that occurring at wavelengths longer than 15 microns) makes up 60% of the thermal emission from the Arctic and nearly half of Earth's emission, globally.           Remarkably, however, while far-infrared spectra have been collected from every planet in the solar system, Earth's far-infrared emission spectrum has never been systematically documented. These measurements could offer powerful new insights into the key processes at work in the rapidly changing Arctic. This presentation will describe a new satellite mission concept aimed at addressing this critical observational gap. The Polar Radiant Energy in the Far-InfaRed Experiment (PREFIRE) utilizes two CubeSats in asynchronous orbits to systematically document the spectral variation of thermal emission across the mid- and far-infrared (5 – 45 microns) throughout the Arctic. We anticipate that the resulting measurements will reveal changes in the full spectrum of Arctic radiant energy associated with processes that operate on scales ranging from sub-daily to seasonal. By distinguishing the unique spectral fingerprints of changes in temperature, water vapor, clouds, and surface melt processes, PREFIRE will help untangle the complex time-varying errors in model physics responsible for the large spread in simulations of the Arctic energy budget.