CW3E Members Attend 4^th Annual Atmospheric River Reconnaissance Workshop at ECMWF in Reading, UK

July, 13 2023

Members of CW3E’s AR Recon team attended the 4th Annual Atmospheric River Reconnaissance (AR Recon) Workshop at the European Centre for Medium-Range Weather Forecasts (ECMWF) held in Reading, UK and online during June 27–30, 2023. The goals of this workshop included highlighting the accomplishments of the exceptionally active 2023 AR Recon season and spotlighting the impact of data collected and assimilated during AR Recon into various operational weather models. The workshop also previewed research in progress using data collected during the season, discussed the upcoming collaboration between the North Atlantic Waveguide, Dry Intrusion, and Downstream Impact Campaign (NAWDIC) and AR Recon, and discussed future plans for the growth of AR Recon. Organization of the workshop was guided by the AR Recon Modeling and Data Assimilation Steering Committee.

The first day of the workshop began with opening remarks by Florian Pappenberger, Director of Forecasts & Deputy-Director General at ECMWF, and a presentation on AR Recon motivation and achievements by Marty Ralph, CW3E Director and PI of AR Recon. The remainder of the day focused on AR Recon during Water Year 2023 (and, at times, beyond). The morning sessions focused primarily on observational platforms and techniques associated with AR Recon, as well as analysis of the meteorological characteristics associated with landfalling ARs based on AR Recon observations. The afternoon sessions focused primarily on the use of sensitivity products, both the adjoint and ensemble methods, to highlight areas where targeted AR Recon observations, particularly dropsondes, would be most beneficial to the accuracy of numerical weather prediction model run solutions. The importance of AR Recon to water management operations was also highlighted by Cary Talbot, National Lead, Forecast-Informed Reservoir Operations Program (FIRO) at the US Army Engineer Research & Development Center. The day concluded with a reception and poster viewing session.

The second day of the workshop began with a presentation by Rear Admiral Nancy Hann, Director of the NOAA Office of Marine and Aviation Operations (OMAO), describing NOAA’s current and future aircraft support for AR Recon, followed by an overview of AR Recon observational strategies and impacts on NOAA/NCEP modeling by Vijay Tallapragada, Senior Scientist for EMC and Co-PI of AR Recon. The remainder of the morning continued to focus on modeling, data assimilation, and impact studies related to AR Recon observations. This general theme continued into the afternoon, which featured a celebration of ECMWF’s successful implementation of its newest version of the Integrated Forecasting System (Cycle 48r1). Chris Davis, NCAR Senior Scientist and Chair, WMO WWRP Science Steering Committee, highlighted activities of the World Weather Research Programme relevant to AR Recon. The day concluded with a workshop dinner at Bel and the Dragon in the Reading town centre.

The third day of the workshop was kicked off by Helen Dacre, Professor of Meteorology at the University of Reading, who presented on precipitation efficiencies in extratropical cyclones and the role of ARs. The remainder of the morning session continued with a focus on scientific advances in physical process understanding and how these advances could be considered and/or applied toward future AR Recon targeting operations. Topics included interactions between the WCB and the jet stream, dry intrusions, and even tropical cyclones in the western Pacific. The afternoon featured a panel discussion regarding new directions and the future of AR Recon. Each member of the audience was invited to provide one comment based on the workshop, and a wide variety of constructive ideas was discussed.

The fourth day of the meeting transitioned to the NAWDIC Workshop, with a presentation from Christian Grams, Professor of Meteorology at the Karlsruhe Institute of Technology outlining the primary field campaign and its various complementary projects. CW3E Director, Marty Ralph, gave a presentation on the potential collaborations between AR Recon and the NAWDIC campaign, discussing the potential for coordinating sampling flights off the US East Coast with flights over Europe. The morning session featured discussion of various projects that will occur under the NAWDIC umbrella, including the UK led CAPRI field campaign (Cyclones, coupled Atmosphere-surface, Processes and Risk of Impacts), French led contributions via SAFIRE aircraft and ground-based sensor deployment, and proposed US plans to sample upstream, antecedent atmospheric conditions associated with high-impact weather events. The day finished with breakout group sessions on Atmospheric Rivers and Dry Intrusions, the presentation of a case study representing the full collaborative efforts of the group, and reporting on the results of the breakout group discussions.

The full meeting agenda, recording of each talk, copies of presentation slides, and posters presented at the meeting can be found here, on the ECMWF’s website for the event.

AR Recon Workshop Session Topics

AR Recon in Water Year 2023

Modeling, Data Assimilation and Impact Studies

Scientific Advances in Physical Process Understanding

The Future of AR Recon

Attendees of the 4th Annual Atmospheric River Reconnaissance Workshop at the European Centre for Medium-Range Weather Forecasts offices in Reading, UK (27 June 2023, Photo: ECMWF)