Space climate and space weather over the past 400 years: 2. Proxy indicators of geomagnetic storm and substorm

TL;DR

This study reconstructs 400 years of space climate and space weather indicators using geomagnetic proxies, providing insights into historical geomagnetic activity and predicting future disturbances during minima.

Contribution

It introduces a physics-based method to quantify historical space weather conditions and extends understanding of geomagnetic activity during past minima.

Findings

Reconstructed annual geomagnetic indices over 400 years.

Estimated fraction of storm-like days and hours with 50-60% accuracy.

First quantification of space weather during Dalton and Maunder minima.

Abstract

Using the reconstruction of power input to the magnetosphere given in Paper 1 (arXiv:1708.04904), we reconstruct annual means of geomagnetic indices over the past 400 years to within a 1-sigma error of +/-20 pc. In addition, we study the behaviour of the lognormal distribution of daily and hourly values about these annual means and show that we can also reconstruct the fraction of geomagnetically-active (storm-like) days and (substorm-like) hours in each year to accuracies of 50-60 pc. The results are the first physics-based quantification of the space weather conditions in both the Dalton and Maunder minima. We predict terrestrial disturbance levels in future repeats of these minima, allowing for the weakening of Earth's dipole moment.