Characterization of the atmospheric environment during extreme precipitation events associated with atmospheric rivers in Norway - Seasonal and regional aspects

Clio Michel, Asgeir Sorteberg, Sabine Eckhardt, Chris Weijenborg, Andreas Stohl, Massimo Cassiani

Publications: Contribution to journalArticlePeer Reviewed

Abstract

Extreme precipitation events in Norway in all seasons are often linked to atmospheric rivers (AR). We show that during the period 1979–2018 78.5% of the daily extreme precipitation events in Southwestern Norway are linked to ARs, this percentage decreasing to 59% in the more northern coastal regions and ~40% in the inland regions. The association of extreme precipitation with AR occurs most often in fall for the coastal areas and in summer inland. All Norwegian regions experience stronger winds and 1–2°C increase of the temperature at 850 hPa during AR events compared to the climatology, the extreme precipitation largely contributing to the wet climatology (only considering rainy days) in Norway but also in Denmark and Sweden when the rest of Europe is dry. A cyclone is found nearby the AR landfall point in 70% of the cases. When the cyclone is located over the British Isles, as it is typically the case when ARs reach Southeastern Norway, it is associated with cyclonic Rossby wave breaking whereas when the ARs reach more northern regions, anticyclonic wave breaking occurs over Northern Europe. Cyclone-centered composites show that the mean sea level pressure is not significantly different between the eight Norwegian regions, that baroclinic interaction can still take place although the cyclone is close to its decay phase and that the maximum precipitation occurs ahead of the AR. Lagrangian air parcel tracking shows that moisture uptake mainly occurs over the North Atlantic for the coastal regions with an additional source over Europe for the more eastern and inland regions.
Original languageEnglish
Article number100370
Number of pages15
JournalWeather and Climate Extremes
Volume34
DOIs
Publication statusPublished - Dec 2021

Austrian Fields of Science 2012

  • 105206 Meteorology

Keywords

  • Atmospheric rivers
  • EXTRATROPICAL CYCLONES
  • Extreme precipitation events
  • FUTURE CHANGES
  • INLAND PENETRATION
  • Large-scale atmospheric circulation
  • MOISTURE SOURCES
  • NORTHERN-HEMISPHERE
  • PACIFIC-OCEAN
  • PART I
  • Rossby wave breaking
  • WAVE-BREAKING
  • WEST-COAST
  • WINTER PRECIPITATION

Cite this