Multipole structure of the heliomagnetic field and northsouth asymmetry in the heliospheric current sheet

Abstract

North-South asymmetry in the heliospheric current sheet (HCS) defined as the difference in the maximum helioatitudinal extension of the HCS in the northern and southern heliospheres, can be classified into two different types. In the first type of asymmetric HCS, the transition heliographic latitude Teta T where the dominant polarity of the IMF observed during a solar rotation reverse sign, lies in the same heliohemisphere where the HCS has maximum helioatitudinal extension, while in the second type of asummetric HCS the opposite is true. Fourier spectra of the inferred HCS using white light corona observations during few solar rotations suggest diffrent solar origins for the two types of asymmetric HCS structures. In the first type of HCS the dc component of the fourier spectra is prominent and the centre of the Sun, while for the second case the dc component is not so prominent and the asymmetry arises mainly due to the presence of various magnetic multipoles in the heliomagnetic field.