Epoch‐Based Model for Stormtime Plasmapause Location

Abstract

The output of a plasmapause test particle (PTP) code is used to formulate a new epoch-based plasmapause model. The PTP simulation is run for an ensemble of 60 storms spanning 3 September 2012 to 28 September 2017 and having peak D st of −60 nT or less, yielding over 7 million model plasmapause locations. Events are automatically identified and epoch times calculated relative to the respective storm peaks. Epoch analysis of the simulated plasmapause is demonstrated to be an effective method to reveal the dynamical phases of plume formation and evolution. The plasmapause radius is found to be strongly correlated with positive solar wind electric field. The epoch-binned PTP data are used to create the first analytical model of the plasmapause that explicitly includes plumes. We obtain this result by employing as basis functions our derived exact solutions for the Volland-Stern convection potential. The analytical plasmapause model depends on epoch time, for moderate and strong storms, and is specified by three main parameters: the duskside plasmapause radius and two tuning coefficients. The epoch-based analytical model is shown to agree to within 0.5 R E with nightside in situ plasmapause crossings by the Van Allen Probes on 17 March 2015. Compared to dayside plume crossings on 26 June 2000, the model agrees within 0.7 R E of radius and 0.8 R E azimuthal distance. This level of agreement is comparable to that achieved by the full dynamic PTP simulation.

Feedback Interactions Between the Ionosphere and Magnetosphere at Middle Latitude

“…This location corresponds to the location of the plasmapause which is moved to middle latitudes during the substorm compared to its location during quiet times, as reported by Goldstein et al. (2019). Figure 3c shows a less sharp gradient around L = 2.7, which suggests that the plasmapause is being gradually shifted back to higher latitudes: from L = 2.8 in Figure 3b to around L = 2.85 and L = 3 in Figure 3c.…”

“…Figures 3a and 3b show a relatively strong gradient in the electron density in the region around L = 2.7-2.8, where the density changes from ≈400 cm −3 at L = 2.8 to ≈1400 cm −3 at L = 2.6. This location corresponds to ALIMAGANBETOV AND STRELTSOV 10.1029/2021JA029990 5 of 15 the location of the plasmapause which is moved to middle latitudes during the substorm compared to its location during quiet times, as reported by Goldstein et al (2019). Figure 3c shows a less sharp gradient around L = 2.7, which suggests that the plasmapause is being gradually shifted back to higher latitudes: from L = 2.8 in Figure 3b to around L = 2.85 and L = 3 in Figure 3c.…”

Role of Ducting in Relativistic Electron Loss by Whistler‐Mode Wave Scattering

“…Interestingly, the most effective electron acceleration by whistlers is associated with plasma density depletions (Agapitov et al., 2019; Allison et al., 2021; Summers et al., 1998; Thorne et al., 2013). Therefore, the regime of electron interaction with whistlers may be controlled also by the spatial distribution of plasma density, and this significantly increases the importance of developing more realistic plasma density models (Chu et al., 2017; Goldstein et al., 2019; Zhelavskaya et al., 2017).…”

The Roles of the Magnetopause and Plasmapause in Storm‐Time ULF Wave Power Enhancements

“…These instances are likely during the storm main phase and in the noon and post‐noon MLT sectors. During geomagnetically active periods, it is well‐established that strong enhancements in solar wind ‐ magnetosphere coupling and the convective electric field significantly distort and erode the plasmasphere, resulting in the formation of a plasmaspheric plume and detached plasmaspheric plasma within the afternoon sector plasmatrough (Chappell, 1972; Goldstein et al., 2019; Sandhu et al., 2017; Spasojević et al., 2003). We infer that it is these plumes and detached material that is, sampled at high L values.…”