Abrupt regime shifts in the North Atlantic atmospheric circulation over the last deglaciation

Marcus Löfverström, Juan M. Lora

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


We analyze modeling results of the North Atlantic atmospheric winter circulation from a transient climate simulation over the last 21,000 years. In agreement with previous studies, we find that the midlatitude jet stream assumes a strong, stable, and zonal disposition so long as the North American ice sheets remain in their continent-wide Last Glacial Maximum (LGM) configuration. However, when the Laurentide ice sheet (LIS) and Cordilleran ice sheet separate (∼14,000 years ago), the jet stream abruptly changes to a tilted circulation regime, similar to modern. The proposed explanation is that the dominant stationary wave source in the North Atlantic sector changes from the LIS to the Cordilleran mountain range during the saddle collapse. As long as the LIS dominates, the circulation retains the zonal LGM state characterized by prevalent stationary wave reflection in the subtropical North Atlantic. When the Cordillera takes over, the circulation acquires its modern disposition with a weak and meridionally tilted jet stream and storm track.

Original languageEnglish (US)
Pages (from-to)8047-8055
Number of pages9
JournalGeophysical Research Letters
Issue number15
StatePublished - Aug 16 2017
Externally publishedYes


  • atmosphere-ice sheet interactions
  • circulation regimes
  • deglacial climate
  • jet stream
  • planetary wave reflection
  • stationary waves

ASJC Scopus subject areas

  • Geophysics
  • General Earth and Planetary Sciences


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