Machine Learning Applications to Kronian Magnetospheric Reconnection Classification

Tadhg Garton,Caitriona Jackman,Shane Maloney,Kiley Yeakel,Andrew Smith

doi:10.5194/epsc2020-854

Abstract

&lt;p&gt;Signatures of magnetic reconnection in Saturn's magnetotail are identified in magnetometer observations by characteristic deviations in the northward component of the magnetic field. These magnetic deflections are caused by travelling plasma structures created by reconnection rapidly passing over the observing spacecraft. The identification of these reconnection signatures has long been performed by eye, and more recently through semi-automated methods, however these methods are often limited through a required human verification step. Here, we present a fully automated, supervised learning machine learning (ML) model to identify evidence of reconnection in Cassini MAG (magnetometer) observations of the Kronian magnetosphere, constructed using the Smith et al, 2016. reconnection catalogue which contains hundreds of examples of plasmoids, travelling compression regions and dipolarizations. This ML model is capable of rapidly identifying reconnection events in large time-span Cassini datasets, tested against the full year of 2010 with a high level of accuracy (99\%), true skill score (0.97), and Heidke skill score (0.85). From this ML model, a full cataloguing and examination of magnetic reconnection in the Kronian magnetosphere across Cassini's near Saturn lifetime is now possible.&lt;/p&gt;

Highlights

Magnetic reconnection is the primary process whereby magnetic fields under strain can reconfigure and energy within their structure can transfer
By examining only the neural network reconnection identifications that could be recognized by the S16, and comparing events as a whole, by considering sequential positive minute-byminute classifications as part of the same event, a new confusion matrix is obtained for the entirety of 2010
The operations and effectiveness of machine learning (ML) approaches to magnetic reconnection identification have been discussed

Summary

Introduction

Magnetic reconnection is the primary process whereby magnetic fields under strain can reconfigure and energy within their structure can transfer. On the night-side (0–6 and 18–24 local time), open planetary magnetic field lines become distended in an extended planetary magnetotail, within which field lines may reconnect to again form closed field lines (Dungey, 1961; Dungey, 1965). This cyclic transition between open and closed field configurations allows the transfer of mass, both in and out, of the planetary. At Jupiter and Saturn fast rotation rates and significant internal mass sources result in the operation of the Vasyliunas cycle In this cycle mass is lost down the magnetotail through the reconnection of centrifugally stretched, mass loaded field lines (Vasyliunas, 1983)

Results

Discussion

Conclusion