@article{d7e942a5aa1249b1ab3c6a06775b1ec5,
title = "Glacial reduction of the North American Monsoon via surface cooling and atmospheric ventilation",
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.",
keywords = "North American Monsoon, albedio, ice sheet, paleoclimate, ventilation",
author = "Tripti Bhattacharya and Tierney, {Jessica E.} and Pedro DiNezio",
note = "Funding Information: We wish to acknowledge members of NCAR's Climate Modeling Section, CESM Software Engineering Group (CSEG), and Computation and Information Systems Laboratory (CISL) for their contributions to the development of CESM. P.D.N. gratefully acknowledges CGD for supporting a long-term visit to NCAR when these simulations were performed. Funding for the simulations presented here was provided by NSF (grants AGS-1204011 and OCN-1304910). T.B. and J.E.T. acknowledge a David and Lucile Packard Foundation Fellowship in Science and Engineering to J.E.T. as well as NSF grant OCE-1651034. The source code for CESM1.2 is freely available at http://www.cesm.ucar.edu/models/cesm1.2/ following registration. Both the data and input files, as well as model output, will be made available upon request to P.D.N. The data are archived at the University of Texas at Austin Institute for Geophysics. We thank the developers of NCAR's Command Language (NCL), which was used to perform these analyses. We thank the Editor and two reviewers for comments that greatly improved this manuscript. Publisher Copyright: {\textcopyright}2017. American Geophysical Union. All Rights Reserved.",
year = "2017",
month = may,
day = "28",
doi = "10.1002/2017GL073632",
language = "English (US)",
volume = "44",
pages = "5113--5122",
journal = "Geophysical Research Letters",
issn = "0094-8276",
publisher = "American Geophysical Union",
number = "10",
}