Atmospheric rivers over Scandinavia: Pathways and precipitation

Abstract

Atmospheric rivers (ARs) are narrow corridors of intense water‑vapor transport in the atmosphere. It is well known that ARs are critical drivers of regional precipitation and water supply in many parts of North America and East Asia. However, their role in Scandinavian hydroclimate is less well understood.

In this seminar, I will present a climatology of ARs making landfall in Scandinavia during 1980–2019 using AR detections from the Atmospheric River Tracking Method Intercomparison Project. Combined with ERA5 reanalysis precipitation data, we show that ARs occur up to 5.9% of the time in the most active regions, yet deliver up to 40.7% of annual precipitation in some locations. Through cluster analysis, we identify four distinct AR pathways associated with different precipitation patterns across Scandinavia. Finally, we relate AR variability to the large-scale circulation pattern of the North Atlantic Oscillation. Our results show that although Scandinavian ARs are relatively infrequent, they contribute a disproportionate share of the total annual precipitation.

Key topics

– Climate variability and extremes in the form of atmospheric rivers

– Impacts on precipitation in Scandinavia

– Methodological challenges and uncertainty quantification

Speaker

Hans Chen, PhD, Assistant Professor, Chalmers University of Technology.

Hans Chen is an Earth system scientist with a background in atmospheric and climate science. His research examines the Earth-system linkages that drive climate variability and change, with a particular emphasis on Arctic–mid-latitude connections and the terrestrial carbon cycle. He also develops new approaches to quantify fossil fuel emissions by integrating in situ and satellite observations with models using advanced data fusion techniques. At Chalmers, he leads the Climate Dynamics Group (https://climatedynamics.group), which studies topics including atmospheric rivers, atmospheric moisture dynamics, and the impacts of weather extremes on ecosystems, human health, and society

Highlights

– Expert perspective: Emerging methodologies and new findings on precipitation dynamics in Scandinavia

– Interactive Q&A: Engage directly with the speaker during the live session

– Hybrid format: Attend at Geocentrum or online via Zoom