Temperature and Circulation Anomalies in the Eastern Canadian Arctic, Summer 1946-76
INSTAAR Occasional Paper 34
1980, 159 pp. (cost: $5)
Baffin Island and nearby regions of the eastern Canadian Arctic have been the focus of many recent and ongoing paleoclimatic and glaciological studies. The region is very suitable for these studies because of the sensitivity of regional ice and snow conditions to small changes in summer temperature (which average a few degrees above freezing). Baffin Island’s location beneath one of the major features of the general atmospheric circulation, a trough in the upper westerlies, raises the possibility that regional climate variations may be closely linked to changes in the global-scale climate and circulation. The existence of such a link would greatly enhance the importance of Baffin Island paleoclimatic and glaciological studies.
In this study, thirty summers (1946–76) of surface temperature and pressure, and upper air data for the Baffin region, the Arctic, and the extratropical northern hemisphere, are analyzed to establish the nature and significance of the regional-global summer climate and circulation links.
The variability of Baffin area summer temperatures is shown to be statistically significant on time scales greater than two years and to be closely correlated with the variability of the Arctic zonal average summer temperature. The most significant climatological event at Baffin Island during the thirty summers of record is the cooling of the early 1960’s; this event is given special emphasis in this study.
From an analysis of daily surface synoptic pressure patterns, subjective surface cyclone tracks, and 500 mb positive vorticity flux, it is found that colder summers at Baffin Island are associated with an increase of cyclone activity over Baffin Bay and an intensification of the Arctic front storm track across northern Canada. Colder summers are also associated with eastward displacements of the upper (500 mb and 700 mb) Baffin trough, which in turn are associated with stronger upper westerly winds at the latitude of the trough and over most of the northern hemisphere. Stronger westerly winds are shown to be related to greater meridional temperature gradients associated with general hemispheric coolings.
Because of the regional-global scale correlations found in this study, Baffin Island appears to be a significant indicator of larger-scale summer climate conditions and of the nature of the general circulation over time scales from 2 to 10 years. These correlations do not weaken within these time scales, and may very well extend to the time scales of interest to paleoclimatologists and glaciologists.