Stationary wave reflection as a mechanism for zonalizing the atlantic winter jet at the LGM

Marcus Löfverström, Rodrigo Caballero, Johan Nilsson, Gabriele Messori

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

Current estimates of the height of the Laurentide Ice Sheet (LIS) at the Last Glacial Maximum (LGM) range from around 3000 to 4500 m. Modeling studies of the LGM, using low-end estimates of the LIS height, show a relatively weak and northeastward-tilted winter jet in the North Atlantic, similar to the modern jet, while simulations with high-end LIS elevations show a much more intense and zonally oriented jet. Here, an explanation for this response of the Atlantic circulation is sought using a sequence of LGM simulations spanning a broad range of LIS elevations. It is found that increasing LIS height favors planetary wave breaking and nonlinear reflection in the subtropical North Atlantic. For high LIS elevations, planetary wave reflection becomes sufficiently prevalent that a poleward-directed flux of wave activity appears in the climatology over the midlatitude North Atlantic. This entails a zonalization of the stationary wave phase lines and thus of the midlatitude jet.

Original languageEnglish (US)
Pages (from-to)3329-3342
Number of pages14
JournalJournal of the Atmospheric Sciences
Volume73
Issue number8
DOIs
StatePublished - Aug 1 2016
Externally publishedYes

Keywords

  • Atm/ocean structure/ phenomena
  • Atmospheric
  • Circulation/ dynamics
  • Ice age
  • Nonlinear dynamics
  • Planetary waves
  • Rossby waves
  • Waves

ASJC Scopus subject areas

  • Atmospheric Science

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