The North Atlantic Waveguide, Dry Intrusion, and Downstream Impact Campaign (NAWDIC)

Dry intrusions emerge as an important component of the extratropical circulation. Governing damaging winds directly, and triggering moisture uptake – thus influencing heavy precipitation indirectly, it is necessary to observe dry intrusions and accurately predict them. NAWDIC is a new initiative for an international field campaign aiming to advance our understanding and modelling of the synoptic- to micro-scale dynamical and physical processes associated with the triggering of severe wind gusts, heavy precipitation, and cold air outbreaks in the North Atlantic-European region. More specifically, NAWDIC will focus on the physical understanding and quantification of the interactions between mesoscale tropopause structure, dry intrusion airstream, and downstream dynamics near the surface cold front for the evolution of high-impact weather in winter extratropical cyclones. Initiated as a campaign with the German high-altitude, long-range aircraft HALO, NAWDIC has become a major international effort. It consists of multiple components, which are planned as stand-alone measurement campaigns by different groups in Europe and North America but will benefit from synergies when coordinated under the umbrella of NAWDIC. During the six-week core observation period in January and February 2026, the HALO aircraft will operate from Shannon (Ireland) and will be complemented by in-situ and remote sensing instruments onboard of additional mid- to long range aircrafts as well as dense ground-based measurements at the French Atlantic coast. Further, the observation activities will be accompanied by a modelling component in collaboration with weather services including the assimilation of NAWDIC observations. This presentation will outline the scientific idea behind NAWDIC and the observational strategies for addressing its goals.