An empirical RBF model of the magnetosphere parameterized by interplanetary and ground‐based drivers

Abstract

In our recent paper (Andreeva and Tsyganenko, 2016), a novel method was proposed to model the magnetosphere directly from spacecraft data, with no a priori knowledge nor ad hoc assumptions about the geometry of the magnetic field sources. The idea was to split the field into the toroidal and poloidal parts and then expand each part into a weighted sum of radial basis functions (RBF). In the present work we take the next step forward by having developed a full‐fledged model of the near magnetosphere, based on a multiyear set of space magnetometer data (1995–2015) and driven by ground‐based and interplanetary input parameters. The model consolidates the largest ever amount of data and has been found to provide the best ever merit parameters, in terms of both the overall RMS residual field and record‐high correlation coefficients between the observed and model field components. By experimenting with different combinations of input parameters and their time‐averaging intervals, we found the best so far results to be given by the ram pressure Pd, SYM‐H, and N‐index by Newell et al. (2007). In addition, the IMF By has also been included as a model driver, with a goal to more accurately represent the IMF penetration effects. The model faithfully reproduces both externally and internally induced variations in the global distribution of the geomagnetic field and electric currents. Stronger solar wind driving results in a deepening of the equatorial field depression and a dramatic increase of its dawn‐dusk asymmetry. The Earth's dipole tilt causes a consistent deformation of the magnetotail current sheet and a significant north‐south asymmetry of the polar cusp depressions on the dayside. Next steps to further develop the new approach are also discussed.

The Role of Current Sheet Scattering in the Proton Isotropic Boundary Formation During Geomagnetic Storms

“…The amount of tail stretching in TA16 was previously reported to be similar to the older T89 model (Tsyganenko & Andreeva, ), which in turn has been reported as producing overstretched fields in the magnetotail (Peredo et al, ; Tsyganenko, ). Haiducek et al () reported understretched fields for T01 and overstretched fields in TS05 and TA16.…”

Plasma Anisotropies and Currents in the Near‐Earth Plasma Sheet and Inner Magnetosphere

“…For sufficiently high | S y m ‐ H |, the curvature current peaks around r ∼ 5–6 R E and reaches ∼5 nA/m 2 . These values are relatively large for nonstorm times (taking into account that we consider S y m ‐ H >− 50 nT) and comparable with the maximum current densities in empirical models (e.g., Sitnov et al, ; Stephens et al, ; Tsyganenko & Andreeva, ; Tsyganenko et al, ). The similarity of results in Figures a and b suggests that the curvature radius derived from the empirical magnetic field model is rather close to the dipole field curvature radius for the investigated range of geomagnetic activity.…”

Validation of Inner Magnetosphere Particle Transport and Acceleration Model (IMPTAM) With Long‐Term GOES MAGED Measurements of keV Electron Fluxes at Geostationary Orbit

“…We are now in the process of testing the Weimer () electric field model incorporated into IMPTAM which depends on the IMF clock angle, IMF total field and components, V SW , P SW , and AL index. For magnetic field, several of the latest models, such as the TA15 Tsyganenko and Andreeva () model and the RBF (Radial Basis Function) model (Andreeva & Tsyganenko, ; Tsyganenko & Andreeva, ) are now being considered.…”