Reconstruction of Magnetospheric Storm-Time Dynamics Using Cylindrical Basis Functions and Multi-Mission Data Mining

N. A. Tsyganenko, V. A. Andreeva, M. I. Sitnov


First results are presented of the modeling of magnetospheric storm events, based on: (i) a new method to represent the magnetic field by means of the so-called cylindrical basis functions, (ii) the data mining approach by Sitnov et al. (2008), and (iii) upgraded and extended pool of multi-mission data taken in 1995-2019. The study is focused on the low-latitude magnetospheric domain in the distance range 3-18 Re bounded by field line shells with footpoint latitudes between -70 and +70 deg. The magnetic configurations are reconstructed from data subsets, selected from the grand database by the nearest-neighbor method, using both interplanetary data and the ground disturbance indices. A strong storm of May 27-29, 2017, has been studied in relation to its effect on the reconfiguration of the low-latitude magnetosphere. The modeling reproduces the main features of the magnetosphere dynamics in terms of the geomagnetic field depression/compression and extremely variable field line stretching. The initial contraction of the magnetosphere during the storm sudden commencement results in a local transient surge of the inner tail current and a dramatic antisunward discharge of the magnetic flux. As the storm progresses, the ring current buildup results in a strongly depressed magnetic field in the inner magnetosphere, which expels the magnetic flux to larger distances and increases the field line connection across the more distant tail plasma sheet. At the same time, a strong dawn-dusk asymmetry is developed due to the formation of the duskside partial ring current, in agreement with previous independent results.
JGRA, published January 11, 2021:

This work was supported by the Russian Foundation for Basic Research (RFBR) grant 20-05-00218.