TY - JOUR

T1 - Global Structure of the Cislunar Magnetotail and Its Evolution During Substorms

AU - Sitnov, M. I.

AU - Stephens, G. K.

AU - Artemyev, A. V.

AU - Motoba, T.

AU - Tsyganenko, N. A.

PY - 2025/7/2

Y1 - 2025/7/2

N2 - So far, the structure and dynamics of the terrestrial magnetotail have largely been investigated within (Formula presented.) ((Formula presented.) is the Earth's radius) because of the lack of in-situ observations beyond that distance, as well as limitations of earlier empirical models. Here we reconstruct the global structure of the cislunar tail within (Formula presented.) using 2011–2023 data from the ARTEMIS mission, the 2010 THEMIS-ARTEMIS transition orbits and other missions, such as IMP-8 and Geotail. The reconstruction is made using a new-generation data mining-based empirical algorithm with minimal ad hoc assumptions on the structure of the equatorial current sheet and its evolution during storms and substorms. It is found that the cislunar tail has a regular structure, stable in the substorm growth phase and regularly changing during the expansion and recovery phases. Substorms likely involve the formation of an X-line around (Formula presented.) and magnetic flux accumulation earthward of it, which persists in the growth phase and flattens out after the substorm onset. Consistent with earlier reconstructions of the shorter tail region, the present ones reveal the near-Earth dipolarization of the magnetic field earthward of (Formula presented.), which is a part of the whole cislunar tail flux redistribution. Thin current sheets embedded into a thicker current halo extend up to 40 (Formula presented.) and may exist at lunar distances, consistent with in-situ ARTEMIS observations, near O-lines of plasmoids/flux ropes.

AB - So far, the structure and dynamics of the terrestrial magnetotail have largely been investigated within (Formula presented.) ((Formula presented.) is the Earth's radius) because of the lack of in-situ observations beyond that distance, as well as limitations of earlier empirical models. Here we reconstruct the global structure of the cislunar tail within (Formula presented.) using 2011–2023 data from the ARTEMIS mission, the 2010 THEMIS-ARTEMIS transition orbits and other missions, such as IMP-8 and Geotail. The reconstruction is made using a new-generation data mining-based empirical algorithm with minimal ad hoc assumptions on the structure of the equatorial current sheet and its evolution during storms and substorms. It is found that the cislunar tail has a regular structure, stable in the substorm growth phase and regularly changing during the expansion and recovery phases. Substorms likely involve the formation of an X-line around (Formula presented.) and magnetic flux accumulation earthward of it, which persists in the growth phase and flattens out after the substorm onset. Consistent with earlier reconstructions of the shorter tail region, the present ones reveal the near-Earth dipolarization of the magnetic field earthward of (Formula presented.), which is a part of the whole cislunar tail flux redistribution. Thin current sheets embedded into a thicker current halo extend up to 40 (Formula presented.) and may exist at lunar distances, consistent with in-situ ARTEMIS observations, near O-lines of plasmoids/flux ropes.

KW - X-lines

KW - cislunar magnetotail

KW - data mining

KW - flux accumulation regions

KW - substorms

KW - thin current sheets

UR - https://www.mendeley.com/catalogue/d7c9c14f-6e68-310b-aa7e-d453ab71c5fa/

U2 - 10.1029/2025JA034018

DO - 10.1029/2025JA034018

M3 - Article

VL - 130

JO - Journal of Geophysical Research: Space Physics

JF - Journal of Geophysical Research: Space Physics

SN - 2169-9380

IS - 7

M1 - e2025JA034018

ER -