The most intense electrical currents in the solar wind: Comparisons between single‐spacecraft measurements and plasma turbulence simulations

Three‐dimensional hybrid simulations of solar wind turbulence near the orbit of the Earth are used to investigate the plasma current density over the range of scales from 0.5 proton inertial lengths to hundreds of proton inertial lengths. The data are analyzed along a simulated spacecraft trajectory in order to directly compare the results against single‐spacecraft measurements. The most intense current densities are identified using an amplitude threshold technique and the properties of 5 σ events identified in the true current density are compared to the properties of 5 σ events identified using a proxy for the current density designed for studies of single‐spacecraft solar wind measurements. The proxy is proportional to the magnitude of the directional derivative of the magnetic field along the spacecraft trajectory. The results from the simulation show that the average properties of 5 σ events observed in the proxy are quantitatively similar to those observed in the true current density, properties such as the spatial size of the events, the nearest neighbor distance, and the peak current density of the events. This provides some justification for the use of the proxy for the statistical analysis of solar wind data even though the simulation indicates that the occurrence times of large‐amplitude events in the proxy are not always a reliable indicator of the occurrence times of large‐amplitude events in the true current density. The physical properties of 5 σ events in simulated spacecraft data show remarkable quantitative agreement with the properties of 5 σ events observed in solar wind data.