The North Atlantic Waveguide and Downstream Impact Experiment

TLDR

NAWDEX investigated how diabatic processes disturb the jet stream and influence downstream high‑impact weather over Europe by coordinating four research aircraft and ground‑based measurements. The experiment executed 49 flights from 17 Sept to 22 Oct 2016 with four aircraft (HALO, DLR Falcon 20, SAFIRE Falcon 20, FAAM BAe 146) equipped with remote‑sensing and in‑situ instruments, complemented by ground observations to capture a wide range of atmospheric phenomena. NAWDEX documented three upstream trigger sequences of waveguide disturbances, their dynamic interaction with the jet stream, and the resulting downstream weather impacts on Europe, providing a rich dataset for future case studies and model evaluations of diabatic influences on Rossby waves.

Abstract

Abstract 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, and coordinated with a suite of ground-based measurements. A total of 49 research flights were performed, including, for the first time, coordinated flights of the four aircraft: the German High Altitude and Long Range Research Aircraft (HALO), the Deutsches Zentrum für Luft- und Raumfahrt (DLR) Dassault Falcon 20, the French Service des Avions Français Instrumentés pour la Recherche en Environnement (SAFIRE) Falcon 20, and the British Facility for Airborne Atmospheric Measurements (FAAM) BAe 146. The observation period from 17 September to 22 October 2016 with frequently occurring extratropical and tropical cyclones was ideal for investigating midlatitude weather over the North Atlantic. NAWDEX featured three sequences of upstream triggers of waveguide disturbances, as well as their dynamic interaction with the jet stream, subsequent development, and eventual downstream weather impact on Europe. Examples are presented to highlight the wealth of phenomena that were sampled, the comprehensive coverage, and the multifaceted nature of the measurements. This unique dataset forms the basis for future case studies and detailed evaluations of weather and climate predictions to improve our understanding of diabatic influences on Rossby waves and the downstream impacts of weather systems affecting Europe.