# Modeling the Sun's open magnetic flux and the heliospheric current sheet

## TL;DR

This paper presents a coupled model of solar magnetic flux and the heliospheric current sheet, validated against observations, enabling better reconstruction of solar magnetic history using sunspot data.

## Contribution

It introduces a coupled simulation approach combining surface flux transport and field extrapolation to model the Sun's open flux and HCS evolution from 1976 onward.

## Key findings

- Model results agree with in-situ magnetic field measurements.
- Reproduces the tilt angle of the heliospheric current sheet.
- Supports potential for historical reconstruction of solar magnetic activity.

## Abstract

By coupling a solar surface flux transport model with an extrapolation of the heliospheric field, we simulate the evolution of the Sun's open magnetic flux and the heliospheric current sheet (HCS) based on observational data of sunspot groups since 1976. The results are consistent with measurements of the interplanetary magnetic field near Earth and with the tilt angle of the HCS as derived from extrapolation of the observed solar surface field. This opens the possibility for an improved reconstruction of the Sun's open flux and the HCS into the past on the basis of empirical sunspot data.