Historical and Projected Distributions of Daily Temperature and Pressure in the Arctic

• Published in: Arctic 2007-12, Vol.60 (4), p.389-400
• Main Authors: Timlin, Michael S., Walsh, John E.
• Format: Article
• Language: English
• Subjects: Atmospheric temperature; Climate change; Climate models; Global temperature changes; Ice; Land; Measurement; Modeling; Ocean temperature; Oceans; Surface temperature; Temperature; Temperature distribution
• ISSN: 0004-0843

Changes in extreme temperatures and pressures in the Arctic have received little attention in the context of climate change. Here we examine the distributions and extremes of surface air temperature and pressure in the Arctic for the late 20th century, using Alaskan weather station data, an atmospheric reanalysis, and general circulation models (GCMs). There is good agreement among these sources for the late 20th century, with broader distributions for both temperature and pressure in winter as compared to summer, and over land as compared to over ocean. We used the output from 21st-century greenhouse simulations by the GCMs to address the occurrence of extremes in the coming decades. The model projections of the 21st-century extremes largely agree with changes in the mean state, with record low temperatures decreasing in frequency and record high temperatures increasing in frequency. The changes in 21st-century extremes are more pronounced over the ocean, where the present-day distributions are narrower. The projected decreases of mean pressure result in more frequent occurrences of extreme low pressure, especially over the Arctic Ocean, although the extremes of pressure are less affected by changes of the means than are the extremes of temperature. Lastly, we find that the transition from sea ice to open water, and associated changes in the salinity of the surface water, can cause changes in the temperature distribution that are more complex than simple shifts in the distribution, leading to unexpected changes in the occurrence of extreme temperatures. /// Les changements en matière de températures et de pressions extrêmes dans l'Arctique reçoivent peu d'attention dans le contexte du changement climatique. Ici, nous examinons les répartitions et les extrêmes de la température de l'air en surface et de la pression dans l'Arctique vers la fin du XXe siècle et ce, en nous appuyant sur les données de la station météorologique de l'Alaska, sur une nouvelle analyse atmosphérique et sur des modèles de circulation générale. Il existe une bonne concordance quant aux sources visant la fin du XXe siècle, avec des répartitions plus vastes pour les températures et pressions d'hiver comparativement à celles de l'été, ainsi que pour les températures et pressions terrestres par rapport aux températures et pressions océaniques. Nous nous sommes également servi des données émanant de simulations de serres au XXIe siècle, réalisées au moyen des modèles de circulation génér