Mean Polar Vortices

• Main Author: James F. Andrews
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1960
• Subjects: Canada; Pacific; Alaska; Siberia
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.395.2969; http://docs.lib.noaa.gov/rescue/mwr/088/mwr-088-05-0193.pdf

The monthly mean circulation at 700 mb. for May 1960 (fig. 1) was characterized by strong blocking over much of the higher latitudes of the Northern Hemisphere. In terms of 700-mb. height anomaly, the principal centers of blocking were located over eastern Canada (+320 ft.) and northern Siberia (+370 ft.) with another, somewhat weaker, center over southwestern Alaska (+ 180 ft.). The effect of this blocking on the mid-latitude planetary circulation was to produce a pattern of truncated troughridge systems with rather short wave spacings. The exception to this was in the Pacific where the weaker Alaskan block was associated with a simple zonal pattern and full-latitude mid-Pacific trough (fig. 1). A further effect of the blocking was to displace the mid-tropospheric westerlies at 700 mb. south of their