Arctic Oscillation

Moritz et al. (2002) revealed the substantial inadequacy of climate models when applied to Arctic conditions. In most cases the calculated AO (Arctic oscillation) trends turned out to be weaker than those observed. Calculated climate warming is greater in the fall over the Arctic Ocean, while observed warming is at a maximum in winter and over the continents in spring. 

Arctic sea ice to 8.5% per decade. Different explanations have been proposed for Arctic sea ice decline, including the strong positive mode of the Arctic Oscillation (AO). This oscillation is an alternating pattern of atmospheric pressure at polar latitudes and mid-latitudes. Data collected by several countries bordering the Arctic allow the construction of maps of the lateral sea ice extent since the beginning of the 20th century (Walsh and Chapman, 2001). 

Since 1970, the Arctic Oscillation, which is a measure of the strength of the circumpolar vortex, has strengthened. This has been found to be consistent with temperature change in the Arctic. ... 

Thus, the Arctic Oscillation should be considered as a physical phenomenon connected with the enhancement of circumpolar vortex and relevant mass and temperature changes in the stratosphere. 

Arctic Oscillation Aerosol Optical Depth Aerosol Optical Thickness Arctic Precipitation Data Archive Asia-Pacific Economic Cooperation Air Pollution transport Model ARCtic System Science Arctic Research Consortium of the U.S. 

The winter warmth after the Pinatubo emption was concentrated over Scandinavia and Siberia and central North America. These temperature anomalies were associated with marked departures in sea-level pressure patterns in the first northern winter. There was a pole-ward shift and strengthening of North Atlantic westerlies at —60° N, associated with corresponding shifts in the positions and strengths of the Iceland Low and Azores High. These effects have been modeled as a result of changes to the atmospheric circulation around the Arctic (the Arctic Oscillation Thompson and Wallace (1998)) arising from the differential heating effects of the volcanic aerosol... 

Stenchikov G., Robock A., Ramaswamy V., Schwarzkopf M. D., Hamilton K., and Ramachandran S. (2002) Arctic Oscillation response to the 1991 Mount Knambo eruption effects of volcanic aerosols and ozone depletion. J. Geophys. Res. Doi 10.1029/2002JD002090 (28 December 2002). 

Thompson D. W. J. and Wallace J. M. (1998) The Arctic Oscillation signature in the wintertime geopotential height and temperature fields. Geophys. Res. Lett. 25, 1297-1300. 

FIGURE 5.9 The southern border of the Arctic Oscillation describing three different phase situations (dotted, thin, bold hne) of standing planetary Rosshy waves which affect strength and direction of winds at the pressure level of 500 hPa as redrawn from Girs (1971). 

FIGURE 5.10 Detrended, standardized (mean —0, standard deviation (STD) = 1) winter series (JFM) of the Arctic Oscillation (AO) (NOAA, 2006d) and of the North Atlantic Oscillation (NAO), expressed by the air pressure difference between Gibraltar in the south and Reykjavik in the north according to Hagen and Feistel (2005). 

FIGURE 5.12 Regression (bold hne) between the Arctic Oscillation (AO, X) shown partially in Fig. 5.10, and the WIBIX (F) for N— 152 overlapping winters (JFM, 1851-2002) the coefficient of determination is —0.65 related confidence ranges for the regression (broken line) and the data (dotted hne) were computed on the 95% confidence level (f-distribution). 

The two atmospheric circulation systems influencing the Baltic Sea area are the. orth Atlantic Oscillation and the Arctic Oscillation (AO). Their variability is produced by changing... 

Finally, increasing attention has recently been given to an important circulation anomaly observed in the Northern Hemisphere (see Box 3.3) and characterized by a nearly symmetric oscillation in temperature, wind, and pressure between the Arctic and mid-latitudes (Thompson and Wallace, 1998). This annular mode of oscillation in the climate system is called the Arctic oscillation (AO), and extends from the surface to the upper stratosphere. The AO affects the strength and location of the Arctic vortex, with associated effects on stratospheric ozone (Wallace and Thompson, 2002). 

Kodera, K., and Y. Kuroda, Tropospheric and stratospheric aspects of the Arctic oscillation. Geophys Res Lett 27, 3349, 2000a. 

Thompson, D.W.J., and J.M. Wallace, The Arctic oscillation signature in the winter geopotential height and temperature fields. Geophys Res Lett 25, 1297, 1998. 

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