Work

Properties of Earthward and Tailward High‐Speed Plasma Flows in Earth's Distant Magnetotail: Solar Cycle and Geomagnetic Activity Dependence

Year: 2025

Type: article

Abstract: High‐speed plasma flows in Earth's magnetotail are important for the global dynamics of the magnetosphere. We survey 11 yrs of high‐speed plasma flows observed by the ARTEMIS spacecraft in Earth's distant magnetotail between X GSE = −52 R E and X GSE = −66 R E to investigate their properties for a wide range of solar and geomagnetic activity levels. We find that tailward and earthward high‐speed flows at these distances exhibit notable asymmetries, with higher ion temperatures and larger dawn‐dusk magnetic field magnitudes in tailward flows compared to earthward flows. These asymmetries suggest that a significant portion of tailward high‐speed flows originate from near‐Earth magnetotail reconnection, while earthward high‐speed flows originate from a distant magnetotail reconnection site tailward of ARTEMIS. The occurrence rate of high‐speed flows follows the solar cycle progression and is about twice as high during solar maximum compared to solar minimum. Furthermore, both tailward and earthward high‐speed flows have higher median ion and electron temperatures, outflow speeds, and dawn‐dusk magnetic fields during solar maximum. In addition to the solar cycle dependence, the ion and electron temperatures in the high‐speed flows increase with increasing geomagnetic activity, for both the Auroral Electrojet (AE) and the Disturbance Storm Time (Dst) indices. Interestingly, during large substorms (AE > 1,100 nT) and geomagnetic storms (Dst < −90 nT), only tailward high‐speed flows are observed at lunar distances in this data set. In essence, our results indicate that the properties of both near‐Earth and distant tail reconnection are functions of the solar cycle and geomagnetic activity.

Source: Journal of Geophysical Research Space Physics

DOI: 10.1029/2025ja034437

Authors: Anissa Pokorny‐Yadav, Marit Øieroset, Tai D. Phan, Andrei Runov, Vassilis Angelopoulos

Institutions: Space Sciences Laboratory, University of California, Berkeley, University of California, Los Angeles

Language: English

Topic: Ionosphere and magnetosphere dynamics

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $4,070

Funders: National Science Foundation, National Aeronautics and Space Administration, Nuclear Safety and Security Commission