Rotation of the solar magnetic field during the ascending phase of solar cycle 25

ABSTRACT We present a comprehensive analysis of solar photospheric rotation during the ascending phase of solar cycle 25 using Carrington synoptic magnetic maps (2019 December–2025 July) and cross-correlation techniques. By constructing rotational profiles and deriving the coefficients $A$ (equatorial rotation rate) and $B$ (latitudinal differential rotation), we investigate their temporal evolution and polarity dependence. Our key findings are as follows: (1) The rotational profile during solar cycle 25 exhibits classic differential rotation, peaking at the equator and decreasing with latitude, along with a transition to quasi-rigid rotation above $55^\circ$. (2) A hemispherically antisymmetric polarity dependence emerges at low-mid latitudes ($0^\circ$–$60^\circ$), where positive-polarity fields rotate faster in the northern hemisphere, while negative-polarity fields dominate in the southern hemisphere. (3) Temporal analysis during solar cycle 25 reveals a significant negative correlation between $A$ and $B$. Notably, negative-polarity fields exhibit stronger $A$–$B$ anticorrelations and larger parameter variations, dominating the total magnetic field evolution.