Ground magnetic observatories measure the Earth’s magnetic field and its coupling with the solar wind responsible for ionospheric and magnetospheric current systems. Predicting effects of solar- and atmospheric-driven disturbances is a crucial task. Using data from the magnetic observatory Chambon-la-Forêt at mid-latitude, we investigate the capability of our developed deep artificial neural networks in the modeling of the contributions above 24 hours and the daily variations. Two neural networks were built with the long short-term memory architecture with multiple layers. Using the data from 1995 onwards, the neural networks were trained with physical parameters indicative of solar variabilities and geographical daily and seasonal variations. By excluding the secular variation owing to the change of the Earth’s intrinsic magnetic field, we demonstrate that our approach can model the observed signals with overall good agreements for both a solar-quiet period in 2009 and a solar-active period in 2012. Particularly, using the walk forward training, we updated our models with new data leading up to the test year. The implication of this work is twofold. First, our approach can be adapted for near real-time prediction of intensity of solar and atmospheric disturbances. Second, the neural networks can be used to model the quiet variations when excluding the solar variabilities with important applications in the calculation of magnetic activity indices. This work is a proof-of-concept that deep neural networks can be used to model solar- and atmospheric-driven perturbations modulated by daily and seasonal variations as recorded at a ground magnetic observatory.

Fundamental processes in plasmas act to convert energies into different forms, e.g., electromagnetic, kinetic and thermal. Direct derivation from the Valsov-Maxwell equation yields sets of equations that describe the temporal evolution of the magnetic, kinetic and internal energies in either the monofluid or multifluid frameworks. In this work we focus on the main terms that affect the changes in the kinetic energy. These are pressure gradient-related terms and electromagnetic terms. The former account for plasma acceleration or deceleration from a pressure gradient, while the latter from an electric field. The overall balance between these terms is fundamental to ensure the conservation of energy and momentum. We use in-situ observations from the Magnetospheric MultiScale (MMS) mission to study the relationship between these terms. We perform a statistical analysis of those parameters in the context of magnetic reconnection by focusing on small-scale Electron Diffusion Regions and large-scale Flux Transfer Events. The analysis reveals a correlation between the two terms in the monofluid force balance, and in the ion force and energy balance. However, the expected relationship cannot be verified from electron measurements. Generally, the pressure gradient related terms are smaller than their electromagnetic counterparts. We perform an error analysis to quantify the expected underestimation of gradient values as a function of the spacecraft separation compared to the gradient scale. Our findings highlight that MMS is capable of capturing energy and force balance for the ion fluid, but that care should be taken for energy conversion terms based on electron pressure gradients.

Calculating the pressure-strain terms has recently been performed to quantify energy conversion between the bulk flow energy and the internal energy of plasmas. It has been applied to numerical simulations and satellite data from the Magnetospheric MultiScale Mission. The method requires spatial gradients of the velocity and the use of the full pressure tensor. Here we present a derivation of the errors associated with calculating the pressure-strain terms from multi-spacecraft measurements and apply it to previously studied examples of magnetic reconnection at the magnetopause and the magnetotail. The errors are small in a dense magnetosheath event but much larger in the more tenuous magnetotail. This is likely due to larger counting statistics in the dense plasma at the magnetopause than in the magnetotail. The propagated errors analyzed in this work are important to understand uncertainties of energy conversion measurements in space plasmas and have applications to current and future multi-spacecraft missions.

The EU H2020 SafeSpace project aims to develop a prototype pipeline that connects several tools in a modular fashion to address the physics of the Sun – Interplanetary space – Earth’s magnetosphere with the ultimate goal to forecast radiation belts dynamics. We present a part of the pipeline called Helio1D that is dedicated to forecasting the solar wind properties at the Lagrangian L1 point. Helio1D models solar wind propagation using input data obtained from the MULTI-VP model, which itself models solar wind emergence near Sun based on magnetograms and coronal field reconstruction. In particular, we aim to forecast the properties of the regular solar wind, as well as Corotating Interaction Regions and their high-speed streams which are most geo-effective (for radiation belts in particular). We take an ensemble forecasting approach to provide optimum forecast up to 2 – 4 days of lead time. We also couple the Helio1D pipeline with neural network models that predict geomagnetic indices such as the Kp index for magnetospheric space weather forecasting. In this presentation, we will present the Helio1D pipeline status, as well as its benchmarking and calibration in order to provide optimum forecasting in real-time. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 870437.

Magnetopause Kelvin-Helmholtz (KH) waves are believed to mediate solar wind plasma transport via small-scale mechanisms. Vortex-induced reconnection (VIR) was predicted in simulations and recently observed using NASA’s Magnetospheric Multiscale (MMS) mission data. Flux Transfer Events (FTEs) produced by VIR at multiple locations along the periphery of KH waves were also predicted in simulations but detailed observations were still lacking. Here we report MMS observations of an FTE-type structure in a KH wave trailing edge during KH activity on 5 May 2017 on the dawnside flank magnetopause. The structure is characterised by (1) bipolar magnetic BY variation with enhanced core field BZ and (2) enhanced total pressure with dominant magnetic pressure. The cross-section size of the FTE is found to be consistent with vortex-induced flux ropes predicted in the simulations. Unexpectedly, we observe an ion jet (VY), electron parallel heating, ion and electron density enhancements, and other signatures that can be interpreted as a reconnection exhaust at the FTE central current sheet. Moreover, pitch angle distributions of suprathermal electrons on either side of the current sheet show different properties, indicating different magnetic connectivities. This FTE-type structure may thus alternatively be interpreted as two interlaced flux tubes with reconnection at the interface as reported by Kacem et al. (2018) and Øieroset et al. (2019). The structure may be the result of interaction between two flux tubes, likely produced by multiple VIR at the KH wave trailing edge, and constitutes a new class of phenomenon induced by KH waves.

Flux Transfer Events (FTEs) are transient phenomena produced by magnetic reconnection at the dayside magnetopause typically under southward interplanetary magnetic field (IMF) conditions. They are usually thought of as magnetic flux ropes with helical structures forming through patchy, unsteady, or multiple X-line reconnection. While the IMF often has a non-zero $B_Y$ component, its impacts on the FTE flux rope helicity remain unknown. We survey Magnetospheric Multiscale (MMS) observations of FTE flux ropes during the years 2015 – 2017 and investigate the solar wind conditions prior to the events. By fitting a force-free flux rope model, we select 84 events with good fits and obtain the helicity sign (i.e., handedness) of the flux ropes. We find that positive (negative) helicity flux ropes are mainly preceded by a positive (negative) $B_Y$ component. This finding is compatible with flux ropes formed through a multiple X-line mechanism.

Flux Transfer Events (FTEs) are transient magnetic flux ropes typically found at the Earth’s magnetopause on the dayside. While it is known that FTEs are generated by magnetic reconnection, it remains unclear how the details of magnetic reconnection controls their properties. A recent study showed that the helicity sign of FTEs positively correlates with the east-west (By) component of the Interplanetary Magnetic Field (IMF). With data from the Cluster and Magnetospheric Multiscale missions, we performed a statistical study of 166 quasi force-free FTEs. We focus on their helicity sign and possible association with upstream solar wind conditions and local magnetic reconnection properties. Using both in situ data and magnetic shear modeling, we find that FTEs whose helicity sign corresponds to the IMF By are associated with moderate magnetic shears while those that does not correspond to the IMF By are associated with higher magnetic shears. While uncertainty in IMF propagation to the magnetopause may lead to randomness in the determination of the flux rope core field and helicity, we rather propose that for small IMF By, which corresponds to high shear and low guide field, the Hall pattern of magnetic reconnection determines the FTE core field and helicity sign. In that context we explain how the temporal sequence of multiple X-line formation and the reconnection rate are important in determining the flux rope helicity sign. This work highlights a fundamental connection between kinetic processes at work in magnetic reconnection and the macroscale structure of FTEs.