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In September and October 2016 the North Atlantic Waveguide and Downstream Impact Experiment (NAWDEX) explored the impact of diabatic processes on disturbances of the jet stream and their influence on downstream high-impact weather through the deployment of four research aircraft, each with a sophisticated set of remote-sensing and in-situ instruments; the German High Altitude and LOng Range Research Aircraft (HALO), the Deutsches Zentrum fur Luft- und Raumfahrt (DLR) Dassault Falcon 20, the French Service des Avions Francais Instrumentions pour la Recherche en Environnement (SAFIRE) Falcon 20, and the British Facility for Airborne Atmospheric Measurements (FAAM) BAe 146. A total of 49 research flights were performed, including, for the first time, coordinated flights of the four aircraft. The aircraft operations were coordinated with a suite of ground-based measurements and the density of operational radiosonde releases was increased which yielded a very high coverage with high-resolution vertical profiles.
The observation period from 17 September to 22 October 2016 was characterized by frequently occurring extratropical and tropical cyclones which was ideal to investigate mid-latitude weather over the North Atlantic. NAWDEX featured three sequences of upstream triggers of waveguide disturbances, their dynamic interaction with the jet stream, a subsequent downstream development, and eventual weather impact on Europe. Periods of reduced predictability were observed.
NAWDEX was first field experiment with synergistic airborne and ground-based observations from the entrance to the exit region of the storm track, taken to investigate the role of diabatic processes in altering jet stream disturbances, their development, and effects on HIW. The unique data set of high resolution wind, water vapor, and cloud information, taking full advantage of recent developments in remote-sensing instrumentation, forms the basis for future case studies and detailed evaluations of weather and climate predictions to improve our understanding of diabatic influences on Rossby wave propagation and downstream impact of weather systems affecting Europe.
NAWDEX research is connected to the scientific community focusing on both weather and climate timescales. Since the finish of THORPEX programme at the end of 2014, the leadership from the PDP WG has transferred to the new World Weather Research Programme (WWRP) WG on Predictability, Dynamics and Ensemble Forecasting (PDEF). NAWDEX also has a strong link to the High Impact Weather project (HIWeather), a new activity of the WWRP. It also deals with one of the four key questions posed by the Grand Challenge on clouds, circulation and climate sensitivity of the World Climate Research Programme (WCRP) for the next decade (Bony et al., 2015).
An NAWDEX overview is given by Schäfler et al. (2018) including the scientific aims, meteorogical situation, description of all airborne and ground-based observations and first scientific higlights
|© 2015 by Institute for Atmospheric and Climate Science, ETH Zurich|