Automatic Detection and Classification of Boundary Crossings in Spacecraft in situ Data

<p>Planetary magnetospheres create multiple sharp boundaries, such as the bow shock, where the solar wind plasma is decelerated and compressed, or the magnetopause, a transition between solar wind field and planetary field.<br />We attempt to use convolutional neural networks (CNNs) to identify magnetospheric boundaries, i.e.  planetary and interplanetary shocks crossings and magnetopause crossings in spacecraft in situ data. The boundaries are identified by a discontinuity in a magnetic field, plasma density, and in the spectrum of high-frequency waves. These measurements are available on many planetary missions. Data from Earth's missions Cluster and THEMIS are used for CNN training. We ultimately strive for successful classification of boundaries (shock, magnetopause, inbound, outbound) and the correct handling of multiple crossings.</p>

Energetic Particles in the Inner Heliosphere: Solar Orbiter

<p>To be measured as energetic particles in the heliosphere ions and electrons must undergo three processes: injection, acceleration, and transport. Suprathermal seed particles have speeds well above the fast magnetosonic speed in the solar wind frame of reference and can vary from location to location and within the solar activity cycle. Acceleration sites include reconnecting current sheets in solar flares or magnetospheric boundaries, shocks in the solar corona, heliosphere and a planetary obstacles, as well as planetary magnetospheres. Once accelerated, particles are transported from the acceleration site into and throughout the heliosphere. Thus, by investigating properties of energetic particles such as their composition, energy spectra, pitch-angle distribution, etc. one can attempt to distinguish their origin or injection and acceleration site. This in turn allows us to better understand transport effects whose underlying microphysics is also a key ingredient in the acceleration of particles.</p><p>In this presentation we will present some clear examples which link energetic particles from their observing site to their source locations. These include Jupiter electrons, singly-charged He ions from CIRs, and 3He from solar flares. We will compare these examples with the measurement capabilities of the Energetic Particle Detector (EPD) on Solar Orbiter and consider implications for the key science goal of Solar Orbiter and Solar Proble Plus – How the Sun creates and controls the heliosphere.</p>

Automatic detection of the electron density from the WHISPER instrument onboard CLUSTER

<p>The Waves of HIgh frequency and Sounder for Probing Electron density by Relaxation (WHISPER) instrument, is part of the Wave Experiment Consortium (WEC) of the CLUSTER mission. The instrument consists basically of a receiver, a transmitter, and a wave spectrum analyzer. It delivers active (sounding) and natural electric field spectra. The characteristic signature of waves indicates the nature of the ambient plasma regime and, combined with the spacecraft position, reveals the different magnetospheric boundaries and regions. The electron density can be deduced from the characteristics of natural waves in natural mode and from the resonance triggered in the sounding mode. The electron density is a parameter of major scientific interest and is also commonly used for the calibration of the particles instruments.</p><p>Until recently, the electron density required a manual intervention consisting in visualizing input parameters from the experiments, such as the WHISPER active/passive spectrograms combined with the dataset from the other instruments onboard CLUSTER.</p><p>Work is being carried out to automatize the detection of the electron density using Machine Learning and Deep Learning methods.</p><p>To automate this process, knowledge of the region (plasma regime) is highly desirable. In order to try to determinate the different plasma regions, a Multi-Layer Perceptron has been implemented. This model consists of three neuronal network dense layers, with some additional dropout to prevent overfitting. For each detected region, a second Multi-Layer perceptron was implemented to determine the plasma frequency. This model has been trained with 100k spectra using the plasma frequency values manually found. The accuracy can reach until 98% in some plasma regions.</p><p>These models of the electron density automated determination are also currently applied on the dataset of the mutual impedance instrument (RPC-MIP) onboarded ROSETTA and will be useful for other space missions such as BepiColombo (especially for PWI/AM<sup>2</sup>P experiment) or JUICE (RPWI/MIME experiment).</p>

Super fast plasma streams as drivers of transient and anomalous magnetospheric dynamics

We present multi spacecraft measurements in the magnetosheath (MSH) and in the solar wind (SW) by Interball, Cluster and Polar, demonstrating that coherent structures with magnetosonic Mach number up to 3 – Supermagnetosonic Plasma Streams (SPS) – generate transient and anomalous boundary dynamics, which may cause substantial displacements of the magnetospheric boundaries and the riddling of peripheral boundary layers. In this regard, for the first time, we describe a direct plasma penetration into the flank boundary layers, which is a candidate for being the dominant transport mechanism for disturbed MSH periods. Typically SPS's have a ram pressure exceeding by several times that of the SW and lead to long-range correlations between processes at the bow shock (BS) and at the magnetopause (MP) on one side and between MSH and MP boundary layers on the other side. We demonstrate that SPS's can be observed both near the BS and near the MP and argue that they are often triggered by hot flow anomalies (HFA), which represent local obstacles to the SW flow and can induce the SPS generation as a means for achieving a local flow balance. Finally, we also discuss other causes of SPS's, both SW-induced and intrinsic to the MSH. SPS's appear to be universal means for establishing a new equilibrium between flowing plasmas and may also prove to be important for astrophysical and fusion applications.