An Initial Intercomparison of Atmospheric and Oceanic Climatology for the ICE-5G and ICE-4G Models of LGM Paleotopography

• Published in: Journal of climate Vol. 19; no. 1; pp. 3 - 14
• Main Authors: Justino, F., Timmermann, A., Merkel, U., Peltier, W. R.
• Format: Journal Article
• Language: English
• Published: Boston, MA American Meteorological Society 01.01.2006
• Subjects: Albedo; Atmosphere; Atmospheric circulation; Atmospheric models; Atmospherics; Cartography; Climate; Climate change; Climate models; Climatology; Climatology. Bioclimatology. Climate change; Earth sciences; Earth, ocean, space; Exact sciences and technology; External geophysics; Glacial landforms; Global climate; Hydrologic cycle; Ice sheets; Marine; Meteorology; Oceans; Paleoclimatology; Paleontology; Paleontology: general; Sea ice; Topography; AN, North Atlantic; Canada; AN, Atlantic; North America; paleorelief; Quaternary; paleoclimatology; topography; Atmosphere cryosphere interaction; Climate models; digital simulation; Ocean dynamics; Last glacial maximum; Sea ice ocean model; paleoclimate; Dynamical climatology; Ocean-atmosphere model; upper Pleistocene; Atmospheric dynamics; ice sheets; climate modification; Planetary scale; Cenozoic; Phanerozoic; Atmosphere sea ice model; Pleistocene; albedo
• ISSN: 0894-8755; 1520-0442
• DOI: 10.1175/jcli3603.1

This paper investigates the impact of the new ICE-5G paleotopography dataset for Last Glacial Maximum (LGM) conditions on a coupled model simulation of the thermal and dynamical state of the glacial atmosphere and on both land surface and sea surface conditions. The study is based upon coupled climate simulations performed with the ocean–atmosphere–sea ice model of intermediate-complexity Climate de Bilt-coupled large-scale ice–ocean (ECBilt-Clio) model. Four simulations focusing on the Last Glacial Maximum [21 000 calendar years before present (BP)] have been analyzed: a first simulation (LGM-4G) that employed the original ICE-4G ice sheet topography and albedo, and a second simulation (LGM-5G) that employed the newly constructed ice sheet topography, denoted ICE-5G, and its respective albedo. Intercomparison of the results obtained in these experiments demonstrates that the LGM-5G simulation delivers significantly enhanced cooling over Canada compared to the LGM-4G simulation whereas positive temperature anomalies are simulated over southern North America and the northern Atlantic. Moreover, introduction of the ICE-5G topography is shown to lead to a deceleration of the subtropical westerlies and to the development of an intensified ridge over North America, which has a profound effect upon the hydrological cycle. Additionally, two flat ice sheet experiments were carried out to investigate the impact of the ice sheet albedo on global climate. By comparing these experiments with the full LGM simulations, it becomes evident that the climate anomalies between LGM-5G and LGM-4G are mainly driven by changes of the earth’s topography.