Interplay of bubble injections in the plasma sheet dynamics as inferred from RCM-I simulations

<p><span>Understanding the transport of hot plasma from tail towards the inner magnetosphere is of great importance to improve our perception of the near-Earth space environment. In accordance with the recent observations, the contribution of bursty bulk flows (BBFs)/bubbles in the inner plasma sheet especially in the storm-time ring current formation is nonnegligible. These high-speed plasma flows with depleted flux tube/entropy are likely formed in the mid tail due to magnetic reconnection and injected earthward as a result of interchange instability. In this presentation, we investigate the interplay of these meso-scale structures on the average magnetic field and plasma distribution in various regions of the plasma sheet, using the Inertialized Rice Convection Model (RCM-I). We will discuss the comparison of our simulation results with the observational statistics and data-based empirical models.</span></p>

Explanation of global plasmapause characteristics in the frame of interchange instability mechanism

<p>Recent statistical studies based on CLUSTER, CRRES, and THEMIS satellite data have provided insight into global plasmapause characteristics: start of erosion between 21-07 MLT and eastward azimuthal propagation. The observed plasmapause behavior is found to agree with the theory of the interchange instability mechanism. We present the results of the plasmapause characteristics obtained with simulations based on this mechanism.</p><p>Here we aim to obtain the same plasmapause characteristics that we previously obtained with simulations using real values of geomagnetic Kp index (which are the proxies for the convection electric field), but using synthetic Kp changes. We show that for that, completely unexpected, instead of many combinations of Kp changes occurring at different UT times (generated for instance with Monte Carlo methods), only 3 Kp jumps occurring at one UT time, leads to the same plasmapause characteristics obtained with simulations using the real Kp values. Therefore, two plasmapause datasets are constructed by setting the following input in the simulations: (a) real values of the geomagnetic Kp index, (b) certain types of time-dependent changes in the Kp (Kp jumps). The Kp jumps include sharp Kp increase, sharp Kp decrease, short time burst enhancement (increase-decrease within 3 hours) in Kp and their combinations in order to obtain plumes, shoulders, and notches, the structures most often observed in nature. The modeled plasmapause is cross-correlated with the Kp index at different 1-hour MLT bins.</p><p>We have shown that the cross-correlation curves provide deep insight into the physical processes related to the plasmapause dynamic and evolution. In single events, plasmapause may undergo complex and different dynamics. Here, we show that global plasmapause motions and deformation in time may be simply explained, at least in the statistical sense. Accordingly, we will demonstrate and discuss that three plasmapause structures and their combinations statistically leave the same imprint in the passage through a specific MLT sector as a combination of the plasmapauses created with a large number of the real Kp changes.  </p>

Observations of Magnetotail Interchange Heads' Signatures at Later Stage of Development

<pre>The kinetic ballooning/interchange instability (BICI) was recently found to produce azimutally narrow interchange <br />heads extending from the near-Earth magnetotail into the dipole region. In their nonlinear evolution individual <br />heads were predicted to grow into transient earthward moving northward magnetic field intensifications <br />(dipolarization fronts; DFs). The distinguished signatures of such fronts would be their oblique propagation <br />and cross-tail localization due to the finite k$_y$ structure of the BICI modes. We compare DFs that were observed <br />by two THEMIS probes at 11 Earth's radii (R$_E$) downtail amidst previously identified interchange heads with a <br />simulated interchange head during later-stage BICI development. The comparison shows that the DFs propagated <br />dawnward at about 45$^{\circ}$ to the earthward direction. The leading edges and trailing tails of the DFs were <br />structured similarly to those of the simulated interchange head. The analysis evidences that BICI indeed releases <br />obliquely propagating azimuthally localized dipolarization fronts in the Earth's magnetotail. </pre>