Polar MM5 Simulations of the Winter Climate of the Laurentide Ice Sheet at the LGM
Optimized regional climate simulations are conducted using the Polar MM5, a version of the fifth-generation Pennsylvania State University-NCAR Mesoscale Model (MM5), with a 60-km horizontal resolution domain over North America during the Last Glacial Maximum (LGM, 21 000 calendar years ago), when mu...
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ftmaineuniv:oai:digitalcommons.library.umaine.edu:ers_facpub-1067 2024-09-15T18:12:22+00:00 Polar MM5 Simulations of the Winter Climate of the Laurentide Ice Sheet at the LGM Bromwich, David H. Toracinta, E. Richard Wei, Helin Oglesby, Robert J. Fastook, James L. Hughes, Terence J. 2004-09-01T07:00:00Z application/pdf https://digitalcommons.library.umaine.edu/ers_facpub/68 https://doi.org/10.1175/1520-0442(2004)017<3415:PMSOTW>2.0.CO;2 https://digitalcommons.library.umaine.edu/context/ers_facpub/article/1067/viewcontent/hughes_17_3415_3433.pdf unknown DigitalCommons@UMaine https://digitalcommons.library.umaine.edu/ers_facpub/68 doi:10.1175/1520-0442(2004)017<3415:PMSOTW>2.0.CO;2 https://digitalcommons.library.umaine.edu/context/ers_facpub/article/1067/viewcontent/hughes_17_3415_3433.pdf This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. In addition, no permission is required from the rights-holder(s) for educational uses. For other uses, you need to obtain permission from the rights-holder(s). Earth Science Faculty Scholarship Earth Sciences text 2004 ftmaineuniv https://doi.org/10.1175/1520-0442(2004)017<3415:PMSOTW>2.0.CO;2 2024-07-24T05:38:40Z Optimized regional climate simulations are conducted using the Polar MM5, a version of the fifth-generation Pennsylvania State University-NCAR Mesoscale Model (MM5), with a 60-km horizontal resolution domain over North America during the Last Glacial Maximum (LGM, 21 000 calendar years ago), when much of the continent was covered by the Laurentide Ice Sheet (LIS). The objective is to describe the LGM annual cycle at high spatial resolution with an emphasis on the winter atmospheric circulation. Output from a tailored NCAR Community Climate Model version 3 (CCM3) simulation of the LGM climate is used to provide the initial and lateral boundary conditions for Polar MM5. LGM boundary conditions include continental ice sheets, appropriate orbital forcing, reduced CO2 concentration, paleovegetation, modified sea surface temperatures, and lowered sea level. Polar MM5 produces a substantially different atmospheric response to the LGM boundary conditions than CCM3 and other recent GCM simulations. In particular, from November to April the upper-level flow is split around a blocking anticyclone over the LIS, with a northern branch over the Canadian Arctic and a southern branch impacting southern North America. The split flow pattern is most pronounced in January and transitions into a single, consolidated jet stream that migrates northward over the LIS during summer. Sensitivity experiments indicate that the winter split flow in Polar MM5 is primarily due to mechanical forcing by LIS, although model physics and resolution also contribute to the simulated flow configuration. Polar MM5 LGM results are generally consistent with proxy climate estimates in the western United States, Alaska, and the Canadian Arctic and may help resolve some long-standing discrepancies between proxy data and previous simulations of the LGM climate. Text Ice Sheet Alaska The University of Maine: DigitalCommons@UMaine |
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Open Polar |
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The University of Maine: DigitalCommons@UMaine |
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ftmaineuniv |
language |
unknown |
topic |
Earth Sciences |
spellingShingle |
Earth Sciences Bromwich, David H. Toracinta, E. Richard Wei, Helin Oglesby, Robert J. Fastook, James L. Hughes, Terence J. Polar MM5 Simulations of the Winter Climate of the Laurentide Ice Sheet at the LGM |
topic_facet |
Earth Sciences |
description |
Optimized regional climate simulations are conducted using the Polar MM5, a version of the fifth-generation Pennsylvania State University-NCAR Mesoscale Model (MM5), with a 60-km horizontal resolution domain over North America during the Last Glacial Maximum (LGM, 21 000 calendar years ago), when much of the continent was covered by the Laurentide Ice Sheet (LIS). The objective is to describe the LGM annual cycle at high spatial resolution with an emphasis on the winter atmospheric circulation. Output from a tailored NCAR Community Climate Model version 3 (CCM3) simulation of the LGM climate is used to provide the initial and lateral boundary conditions for Polar MM5. LGM boundary conditions include continental ice sheets, appropriate orbital forcing, reduced CO2 concentration, paleovegetation, modified sea surface temperatures, and lowered sea level. Polar MM5 produces a substantially different atmospheric response to the LGM boundary conditions than CCM3 and other recent GCM simulations. In particular, from November to April the upper-level flow is split around a blocking anticyclone over the LIS, with a northern branch over the Canadian Arctic and a southern branch impacting southern North America. The split flow pattern is most pronounced in January and transitions into a single, consolidated jet stream that migrates northward over the LIS during summer. Sensitivity experiments indicate that the winter split flow in Polar MM5 is primarily due to mechanical forcing by LIS, although model physics and resolution also contribute to the simulated flow configuration. Polar MM5 LGM results are generally consistent with proxy climate estimates in the western United States, Alaska, and the Canadian Arctic and may help resolve some long-standing discrepancies between proxy data and previous simulations of the LGM climate. |
format |
Text |
author |
Bromwich, David H. Toracinta, E. Richard Wei, Helin Oglesby, Robert J. Fastook, James L. Hughes, Terence J. |
author_facet |
Bromwich, David H. Toracinta, E. Richard Wei, Helin Oglesby, Robert J. Fastook, James L. Hughes, Terence J. |
author_sort |
Bromwich, David H. |
title |
Polar MM5 Simulations of the Winter Climate of the Laurentide Ice Sheet at the LGM |
title_short |
Polar MM5 Simulations of the Winter Climate of the Laurentide Ice Sheet at the LGM |
title_full |
Polar MM5 Simulations of the Winter Climate of the Laurentide Ice Sheet at the LGM |
title_fullStr |
Polar MM5 Simulations of the Winter Climate of the Laurentide Ice Sheet at the LGM |
title_full_unstemmed |
Polar MM5 Simulations of the Winter Climate of the Laurentide Ice Sheet at the LGM |
title_sort |
polar mm5 simulations of the winter climate of the laurentide ice sheet at the lgm |
publisher |
DigitalCommons@UMaine |
publishDate |
2004 |
url |
https://digitalcommons.library.umaine.edu/ers_facpub/68 https://doi.org/10.1175/1520-0442(2004)017<3415:PMSOTW>2.0.CO;2 https://digitalcommons.library.umaine.edu/context/ers_facpub/article/1067/viewcontent/hughes_17_3415_3433.pdf |
genre |
Ice Sheet Alaska |
genre_facet |
Ice Sheet Alaska |
op_source |
Earth Science Faculty Scholarship |
op_relation |
https://digitalcommons.library.umaine.edu/ers_facpub/68 doi:10.1175/1520-0442(2004)017<3415:PMSOTW>2.0.CO;2 https://digitalcommons.library.umaine.edu/context/ers_facpub/article/1067/viewcontent/hughes_17_3415_3433.pdf |
op_rights |
This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. In addition, no permission is required from the rights-holder(s) for educational uses. For other uses, you need to obtain permission from the rights-holder(s). |
op_doi |
https://doi.org/10.1175/1520-0442(2004)017<3415:PMSOTW>2.0.CO;2 |
_version_ |
1810449942892773376 |