THE CIRCULATION AT THE 10-MILLIBAR CONSTANT PRESSURE SURFACE OVER NORTH AMERICA AND ADJACENT OCEAN AREAS

Abstract

A recently published set of 10-mb. charts analyzed three times monthly, July 1957 through June 1958, is used as a basis for discussion of the high stratospheric circulation during those first 12 months of the International Geophysical Year, There is a slow, steady transition from summer easterlies to winter westerlies which appear first in high latitudes and then strengthen and expand southward. In January and February 1958, the circulation breaks down rapidly and in a highly complex manner. By May, polar easterlies become established and spread southward to merge with the intensifying subtropical easterlies. Several related topics on the nature of medium- and large-scale developments are discussed.