Abstract | It is well known that the acoustic frequencies of the Sun vary with the solar cycle and in general, can be used as a tracer of magnetic activity. However, recent studies using intermediate-degree global mode frequencies, both from GONG and MDI,
have shown complex relationship during different phases of the solar cycle. In addition, global frequencies during the extended minimum phase have indicated anti-correlation with the measurements of solar activity indices. In this context, we investigate the temporal variation of the high-degree mode frequencies during the declining phase of the solar cycle 23 and the extended minimum
phase between the cycles 23 and 24. The frequencies are calculated from the GONG+ Dopplergrams using the ring-diagram technique.
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