Işık, Emre2018-07-122018-07-122015-11-012041-82052041-8213https://doi.org/10.1088/2041-8205/813/1/L13https://hdl.handle.net/11413/2021The average tilt angle of sunspot groups emerging throughout the solar cycle determines the net magnetic flux crossing the equator, which is correlated with the strength of the subsequent cycle. I suggest that a deep-seated, non-local process can account for the observed cycle-dependent changes in the average tilt angle. Motivated by helioseismic observations indicating cycle-scale variations in the sound speed near the base of the convection zone, I determined the effect of a thermally perturbed overshoot region on the stability of flux tubes and on the tilt angles of emerging flux loops. I found that 5-20 K of cooling is sufficient for emerging flux loops to reproduce the reported amplitude of cycle-averaged tilt angle variations, suggesting that it is a plausible effect responsible for the nonlinearity of the solar activity cycle.en-USSun: activitySun: interiorSun: magnetic fieldsSunspotsMagnetic-Flux TubesConvection ZoneSolar-CycleBaseSunIntensificationOvershootEnvelopeModelsArticle3644862000133644862000132-s2.0-849476011612-s2.0-84947601161