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

• Published in: Geophysical Research Letters
• Main Authors: Bhattacharya, Tripti, Tierney, Jessica E., DiNezio, Pedro
• Other Authors: Univ Arizona, Dept Geosci, Department of Geosciences; University of Arizona; Tucson Arizona USA, Institute for Geophysics; University of Texas at Austin; Austin Texas USA
• Format: Article in Journal/Newspaper
• Language: English
• Published: AMER GEOPHYSICAL UNION 2017
• Subjects: Ice Sheet
• Online Access: http://hdl.handle.net/10150/625049; https://doi.org/10.1002/2017GL073632

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, 21kaB.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. NSF [AGS-1204011, OCN-1304910, OCE-1651034]; David and Lucile Packard Foundation Fellowship in Science and Engineering 6 month embargo; First published: 27 May 2017 This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [e-mail].