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Link between QBO and TBO in Temperature

Wavelet analysis of temperature anomaly shows QBO in lower stratosphere. Phases of QBO propagate downward with time in the 27-24 km altitudes during 1971-81. Downward phase propagation is disturbed and becomes of constant phase with height at 23-18 km altitudes during the same period. Downward phase propagation of QBO is weak or absent during 1982-92. Phases of QBO and TBO meet at tropopause level or just above 15 km altitude. Where they meet, phases of QBO and TBO are unsynchronized during 1971-81. On the other hand, during 1982-92, phases of QBO and TBO are synchronized there and none of the unusual phenomena of 1971-81 period is manifested.

To get a quantitative idea about the link between QBO and TBO in temperature, the real part of the mean wavelet coefficients of the biennial mode at all levels have been grouped into first (September 1971-December 1981) and second (January 1982-December 1992) decades. Since the QBO signal is prominent at 22 km altitude, QBO at this level is taken as reference QBO and correlation coefficients have been worked out between the real part of the 22 km biennial mode mean wavelet coefficients and those of other levels (1-27 km) for the entire study period and also for the first and second decades separately. The correlation coefficient values are presented in fig. 6.

Correlation coefficients of first and second decades show marked differences. In the first decade, correlation coefficient is positive in the 23-15 km levels and negative above 23 km and below 15 km levels. Opposite signs of correlation in 23-15 km and below 15 km levels clearly show that QBO and TBO phases are unsynchronized during the first decade. Opposite signs between 27-24 km and 23-15 km altitudes show the sudden disturbances in the downward propagating phase of QBO at 23-15 km altitudes. In upper and lower troposphere, magnitudes of correlation are high and it is lowest at 9 km. In the second decade, correlation coefficients are positive at all the levels except tropopause. This shows the existence of phase synchronization between TBO and QBO during this period. For the entire period the correlation show a similar pattern as that of the first decade.

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