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 do 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.
<p>Flux Transfer Events (FTEs) are transient phenomena generated at the dayside magnetopause as a result of magnetic reconnection. FTEs have a significant role in the transfer of momentum and energy into the magnetosphere. We study here, in a multifluid framework, how the energy is converted within FTEs and their surrounding plasma. In particular we investigate how the plasma gains or loses kinetic energy through electric and/or pressure gradient terms. We also investigate the terms that control how the internal energy of the plasma is gained or dissipated through the pressure work term. Using observations from Magnetospheric MultiScale (MMS), we perform a statistical study based on an existing FTE catalog (Fargette et al., 2020). We analyze FTEs with or without internal current sheets. We discuss the contribution of the different terms in the energy conversion process separately for ions and electrons and as a function of location within the FTE. We analyze and compare the results found for FTEs&#8217; intervals with magnetosheath intervals (Wang et al. 2021), taking into account their locations, using probability distribution functions of the various energy terms measured in each interval. This work contributes to a better understanding of energy conversion processes associated with FTEs at the magnetopause.</p>
Flux Transfer Events (FTEs) are magnetic flux ropes produced at the dayside magnetopause as a consequence of magnetic reconnection. They were first observed by Russell and Elphic (1978) using magnetic field measurement from ISEE 1 and 2. An FTE is recognised in in-situ spacecraft time-series data as a bipolar variation in the
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