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We study the response of the low-degree solar p-mode frequencies to theunusual extension of the minimum of solar surface activity since 2007.Helioseismic observations collected by the space-based, Sun-as-a-star GOLFinstrument and by the ground-based, multi-site network GONG (integrated signal)are analyzed. Temporal variations of the low-degree (l=0,1,2), p-modefrequencies are obtained. Although the known correlation of the frequencychanges with the solar surface activity is recovered for the period 1996-2007,since the second half of 2007 and until July 2009 (latest period analyzed) wenotice a peculiar behavior amongst modes of different angular degrees. Inparticular, a clear increase of the l=0 and l=2 p-mode frequencies isconsistently obtained since late 2007, while the l=1 frequencies follow thegeneral decreasing trend of surface activity. We interpret these differences inthe frequency shifts of individual low-degree modes as indicative of variationsat high latitudes in the magnetic flux beneath the surface of the Sun relatedto the onset of solar cycle 24.

Frequency shifts of the individual low-degree p modes during solar cycle 23 and its extended minimum