The solar wind is found by the Parker Solar Probe to be abundant with Alfvénic velocity spikes and magnetic field kinks. Temperature enhancement is another remarkable feature associated with the Alfvénic spikes. How the prototype of these coincident phenomena is generated intermittently in the source region is an important and wide-ranging subject. Here we propose a new model introducing guide-field discontinuity into the interchange magnetic reconnection between open funnels and closed loops with different magnetic helicities. The modified interchange reconnection model not only can accelerate jet flows from the newly opening closed loop but also can excite and launch Alfvénic wave pulses along the newly reconnected and post-reconnected open flux tubes. We find that the modeling results can reproduce the following observational features: (1) Alfvén disturbance is pulsive in time and asymmetric in space; (2) Alfvénic pulse is compressive with temperature enhancement and density variation inside the pulse. We point out that three physical processes co-happening with Alfvén wave propagation can be responsible for the temperature enhancement: (a) convection of heated jet flow plasmas (decrease in density), (b) propagation of compressive slow-mode waves (increase in density), and (c) conduction of heat flux (weak change in density). We also suggest that the radial nonlinear evolution of the Alfvénic pulses should be taken into account to explain the formation of magnetic switchback geometry.

By analyzing the magnetosheath measurements from the Magnetospheric Multiscale Spacecraft, we obtain statistical results for the contribution of magnetic reconnection (MR) events at electron scales to the energy dissipation of coherent structures in shocked turbulent plasmas. The partial variance of increments (PVI) method is employed to find coherent structures in the magnetic field data. We consider criteria to further identify MR events, such as reversal of magnetic field components, significant energy dissipation, and evident electron outflow velocity. Statistically, for most MR events, their PVI values are larger than those of other types of coherent structures, and their energy dissipations are also stronger. However, due to the relatively small number of MR events, their contribution to coherent structures’ energy dissipation is relatively trivial. If the dissipation of non-coherent structures is taken into account, MR’s contribution to energy dissipation would be even less. Hence, we suggest that MR events, though having strong dissipation locally, are not the major contributor to energy dissipation in the turbulent magnetosheath. After analyzing the features of non-MR current sheets, we propose that these are mainly coherent structures inherent to kinetic Alfvén fluctuations.

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