Paleometeorology: High resolution Northern Hemisphere wintertime mid-latitude dynamics during the Last Glacial Maximum

• Published in: Geophysical research letters Vol. 38; no. 23
• Main Authors: Unterman, M. B., Crowley, T. J., Hodges, K. I., Kim, S.-J., Erickson, D. J.
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 01.12.2011; American Geophysical Union; John Wiley & Sons, Inc
• Subjects: Age; Asian; Atmospheric sciences; Climate; Climate science; Climatology; Earth sciences; Earth, ocean, space; Exact sciences and technology; Labrador; Last Glacial Maximum; LGM; LGM storm tracks; Marine; Meteorology; Paleoclimate science; paleometeorology; Storms; Tracking; Weather; United States; Atlantic Ocean; Labrador Sea; Northwest Atlantic; North Pacific; Canada; Asia; Arctic region; North American Atlantic; polar regions; Alaska; Pacific Ocean; North Atlantic; Laurentide ice sheet; Greenland; Mid latitude; atmospheric precipitation; focus; ice; Climate models; climate; Last glacial maximum; monthly average; North America; trajectory; Cyclogenesis; dust storms; drill cores; dynamics; Winter; Northern Hemisphere; interpretation; standard samples; Forcing; reduction; boundary conditions; age; high resolution; statistics
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2011GL049599

Hourly winter weather of the Last Glacial Maximum (LGM) is simulated using the Community Climate Model version 3 (CCM3) on a globally resolved T170 (∼75 km) grid. Results are compared to a longer LGM climatological run with the same boundary conditions and monthly saves. Hourly‐scale animations are used to enhance interpretations. The purpose of the study is to explore whether additional insights into ice age conditions can be gleaned by going beyond the standard employment of monthly average model statistics to infer ice age weather and climate. Results for both LGM runs indicate a decrease in North Atlantic and increase in North Pacific cyclogenesis. Storm trajectories react to the mechanical forcing of the Laurentide Ice Sheet, with Pacific storms tracking over middle Alaska and northern Canada, terminating in the Labrador Sea. This result is coincident with other model results in also showing a significant reduction in Greenland wintertime precipitation – a response supported by ice core evidence. Higher‐temporal resolution puts in sharper focus the close tracking of Pacific storms along the west coast of North America. This response is consistent with increased poleward heat transport in the LGM climatological run and could help explain “early” glacial warming inferred in this region from proxy climate records. Additional analyses shows a large increase in central Asian surface gustiness that support observational inferences that upper‐level winds associated with Asian‐Pacific storms transported Asian dust to Greenland during the LGM. Key Points A reduction in N. Atlantic and increase in N. Pacific LGM cyclogenesis Increased hourly wind velocities over dust source areas during the LGM LGM N. Pacific storms create conditions appropriate for early warming signals