The floor in the interplanetary magnetic field: Estimation on the basis of relative duration of ICME observations in solar wind during 1976-2000

TL;DR

This paper estimates the minimum interplanetary magnetic field (the magnetic field floor) during solar cycle minima by analyzing the duration of ICME observations in solar wind data from 1976 to 2000, avoiding reliance on global solar parameters.

Contribution

It introduces a method to estimate the magnetic field floor using large-scale solar wind types and ICME fractions, providing an alternative to previous approaches.

Findings

Estimated magnetic field floor as 4.65 ± 6.0 nT.

Value agrees with previous estimates.

Method based on ICME observation duration during solar minima.

Abstract

To measure the floor in interplanetary magnetic field and estimate the time- invariant open magnetic flux of Sun, it is necessary to know a part of magnetic field of Sun carried away by CMEs. In contrast with previous papers, we did not use global solar parameters: we identified different large-scale types of solar wind for 1976-2000 interval, obtained a fraction of interplanetary CMEs (ICMEs) and calculated magnitude of interplanetary magnetic field B averaged over 2 Carrington rotations. The floor of magnetic field is estimated as B value at solar cycle minimum when the ICMEs were not observed and it was calculated to be 4,65 \pm 6,0 nT. Obtained value is in a good agreement with previous results.