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 Constant Phase of Temperature TBO with Height

Wavelet analysis shows prominent TBO with periods ranging from 20-32 months in temperature anomaly at almost all levels of troposphere over Thumba. Time sries of real part of the temperature anomaly mean wavelet coefficients corresponding to the biennial mode (20-32 months) for the troposphere and lower stratosphere with 2km uniform interval is presented in fig. 4. This is similar to filtering the biennial mode and removing other modes using standard filtering techniques. The time-height plot of the real part of the mean wavelet coefficients of temperature anomaly corresponding to the biennial mode is presented in fig. 5. Real part of the wavelet coefficients provides information about both the phase and intensity of a signal at a given time and scale relative other times and scales (Weng and Lau, 1994). Amplitude of TBO varies with time and height. TBO is found to be strong during 1971-81 in the troposphere, whereas it is relatively weak during 1982-92. It is clear from figs. 4-5, that the phase of TBO in temperature anomaly from surface to tropopause is nearly constant throughout the study period.

Fig. 5 Time-height plot of  wavelet filtered temperature anomaly corresponding to biennial mode.

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