Effect of Large-Scale Magnetic Fields on Total Solar Irradiance

Abstract

The effect of large-scale magnetic fields on total solar irradiance (TSI) was studied both in time-frequency and in time-longitude aspects. A continuous wavelet analysis revealed that the energy of thermomagnetic disturbances due to sunspots and faculae cascades into the magnetic net- work and facular macrostructure. A numerical technique of time-longitude analysis was developed to study the fine structure of temporal changes in the TSI caused by longitudinal brightness inhomogen- eities and rotation of the Sun. The analysis facilitates mapping large-scale thermal inhomogeneities of the Sun and reveals patterns of radiative excesses and deficits relative to the undisturbed solar photosphere. These patterns are organized into 2- and 4-sector structures that exhibit the effects of both activity complexes and magnetically active longitudes. Large-scale patterns with radiative excess display a facular macrostructure and bright patterns in the magnetic network caused by the dissipation of large-scale thermomagnetic disturbances. Similar global-scale temperature patterns were found in the upper solar atmosphere. These temperature patterns are also causally related to long-lived magnetic fields of the Sun. During activity cycles 21 - 23 the patterns with radiative excess tend to be concentrated around the active longitudes which are centered at about 60 ◦ and 230 ◦ in the Carrington system.