Simulations of Arctic Temperature and Pressure by Global Coupled Models

• Published in: Journal of climate Vol. 20; no. 4; pp. 609 - 632
• Main Authors: Chapman, William L., Walsh, John E.
• Format: Journal Article
• Language: English
• Published: Boston, MA American Meteorological Society 15.02.2007
• Subjects: 20th century; 21st century; Air temperature; Autumn; Bias; Climate change; Climate models; Climatology. Bioclimatology. Climate change; Cold; Earth, ocean, space; Exact sciences and technology; External geophysics; Global climate; Global climate models; Greenhouse effect; Greenhouse gases; Ice; Industrial research; Intergovernmental Panel on Climate Change; International environmental cooperation; Marine; Meteorology; Modeling; Modelling; Oceans; Pressure; Sea ice; Sea level; Sea level changes; Sea level pressure; Seas; Seasons; Simulation; Simulations; Storm tracks; Storms; Surface temperature; Surface-air temperature relationships; Temperature; Variability; Winter; Arctic region; Barents Sea; AN, North Atlantic; PNE, Barents Sea; INE, Bering Sea, Bering Strait; PN, Arctic Ocean; Ensemble simulation; Uncertainty; Century 21st; Spatial variability; trend-surface analysis; General circulation models; Bias; Sea level pressure; Surface temperature; Climate models; digital simulation; Forecast model; troposphere; Dynamical climatology; Century 20th; climate modification; Atmospheric temperature; global change; Arctic Ocean; warming; polar regions; Polar region; seasonal variations
• ISSN: 0894-8755; 1520-0442
• DOI: 10.1175/jcli4026.1

Simulations of Arctic surface air temperature and sea level pressure by 14 global climate models used in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change are synthesized in an analysis of biases and trends. Simulated composite GCM surface air temperatures for 1981–2000 are generally 1°–2°C colder than corresponding observations with the exception of a cold bias maximum of 6°–8°C in the Barents Sea. The Barents Sea bias, most prominent in winter and spring, occurs in 12 of the 14 GCMs and corresponds to a region of oversimulated sea ice. All models project a twenty-first-century warming that is largest in the autumn and winter, although the rates of the projected warming vary considerably among the models. The across-model and across-scenario uncertainties in the projected temperatures are comparable through the first half of the twenty-first century, but increases in variability associated with the choice of scenario begin to outpace increases in across-model variability by about the year 2070. By the end of the twenty-first century, the cross-scenario variability is about 50% greater than the across-model variability. The biases of sea level pressure are smaller than in the previous generation of global climate models, although the models still show a positive bias of sea level pressure in the Eurasian sector of the Arctic Ocean, surrounded by an area of negative pressure biases. This bias is consistent with an inability of the North Atlantic storm track to penetrate the Eurasian portion of the Arctic Ocean. The changes of sea level pressure projected for the twenty-first century are negative over essentially the entire Arctic. The most significant decreases of pressure are projected for the Bering Strait region, primarily in autumn and winter.