Glacial reduction of the North American Monsoon via surface cooling and atmospheric ventilation

Tripti Bhattacharya, Jessica E. Tierney, Pedro DiNezio

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

The North American Monsoon (NAM) provides critical water resources to the U.S. southwest and northwestern Mexico. Despite its importance to regional hydrology, the mechanisms that shape this monsoon are not fully understood. In this paper, we use model simulations of the Last Glacial Maximum (LGM, 21 ka B.P.) to assess the sensitivity of the NAM to glacial boundary conditions and shed light on its fundamental dynamics. We find that atmospheric changes induced by ice sheet albedo reduce NAM intensity at the LGM. The high albedo of the Laurentide ice sheet cools the surface and drives anomalous northwesterly winds that reduce the monsoon circulation and import cold, dry air into the core NAM region. Our work emphasizes the role of ice sheet albedo rather than topography in driving the atmospheric changes that modulate the glacial NAM, and ties our understanding of the NAM to broader theories of monsoon systems.

Original languageEnglish (US)
Pages (from-to)5113-5122
Number of pages10
JournalGeophysical Research Letters
Volume44
Issue number10
DOIs
StatePublished - May 28 2017

Keywords

  • North American Monsoon
  • albedio
  • ice sheet
  • paleoclimate
  • ventilation

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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