Some Influences Responsible for the Interannual Variations in the Stratosphere of the Northern Hemisphere

The longest continuous set of daily analyses of stratospheric constant pressure levels covers 34 years, but the levels are all below 25 km. These analyses are for the Northern Hemisphere and have no equivalent on the Southern Hemisphere. Data from single stations go back another five to eight years. The attempts here to link qualitatively some of the interannual variability in the stratosphere to forcings from outside the stratosphere therefore deal with samples that are not necessarily representative of long periods.In addition to the random interannual variability which is inherent in the atmosphere-ocean system, some of the interannual changes in the stratospheric circulation are associated with the following: 1.The Quasi-Biennial Oscillation in the stratospheric winds above the equator. This oscillation is forced from the troposphere.2.The Southern Oscillation, which is defined as a seesaw in sea level pressure between the Indian and Pacific Oceans but has widespread effects over the globe.3.Major volcanic eruptions, of which there were three during the period analyzed.4.A 10--12 year oscillation which is present in the data of the last 40 years, during which time it was in phase with the 11-year solar cycle.