BIENNIAL VARIATION IN SPRINGTIME TEMPERATURE AND TOTAL OZONE IN EXTRATROPICAL LATITUDES

J. K. ANGELL Institute of Atmospheric Sciences, ESSA, Silver Spring, Md.

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J. KORSHOVER Institute of Atmospheric Sciences, ESSA, Silver Spring, Md.

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Abstract

During the past decade in extratropical latitudes, springtime stratospheric temperatures tended to be relatively high during the even years and relatively low during the odd years, with some evidence for a phase reversal in the troposphere. In the Southern Hemisphere this even-year stratospheric temperature excess appears to have progressed poleward with time, with the maximum excess occurring near the Tropic of Capricorn in 1955 and near the Antarctic Circle in 1965, where the excess averaged 8°C. even at 100 mb.

Total ozone measurements in both hemispheres tend to confirm such a poleward trend. Furthermore, in agreement with a period of order 20 yr. implied by the stratospheric temperature differences, the difference between (spring-time) even-year and odd-year total ozone amounts at Arosa, Switzerland, exhibits about a 20-yr. periodicity from 1928 to 1966, with the ozone amounts averaging 10 percent higher during the spring of the even years around 1960.

Springtime surface temperatures in Scandinavia have undergone a similar (15- to 20-yr.) periodicity since 1850, with odd-year temperature excesses averaging 2°C. around 1959. After 1920, European stations exhibit like variations, but there is little evidence for such surface-temperature fluctuations in North America or in the tropical and temperate latitudes of the Southern Hemisphere.

It is suggested that there is an association between the cycling interval of the quasi-biennial tropical oscillation and the above fluctuations of period of order of 20 yr.

Abstract

During the past decade in extratropical latitudes, springtime stratospheric temperatures tended to be relatively high during the even years and relatively low during the odd years, with some evidence for a phase reversal in the troposphere. In the Southern Hemisphere this even-year stratospheric temperature excess appears to have progressed poleward with time, with the maximum excess occurring near the Tropic of Capricorn in 1955 and near the Antarctic Circle in 1965, where the excess averaged 8°C. even at 100 mb.

Total ozone measurements in both hemispheres tend to confirm such a poleward trend. Furthermore, in agreement with a period of order 20 yr. implied by the stratospheric temperature differences, the difference between (spring-time) even-year and odd-year total ozone amounts at Arosa, Switzerland, exhibits about a 20-yr. periodicity from 1928 to 1966, with the ozone amounts averaging 10 percent higher during the spring of the even years around 1960.

Springtime surface temperatures in Scandinavia have undergone a similar (15- to 20-yr.) periodicity since 1850, with odd-year temperature excesses averaging 2°C. around 1959. After 1920, European stations exhibit like variations, but there is little evidence for such surface-temperature fluctuations in North America or in the tropical and temperate latitudes of the Southern Hemisphere.

It is suggested that there is an association between the cycling interval of the quasi-biennial tropical oscillation and the above fluctuations of period of order of 20 yr.

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