A statistical study on the correlations between plasma sheet and solar wind based on DSP explorations

Abstract

Abstract. By using the data of two spacecraft, TC-1 and ACE (Advanced Composition Explorer), a statistical study on the correlations between plasma sheet and solar wind has been carried out. The results obtained show that the plasma sheet at geocentric distances of about 9∼13.4 Re has an apparent driving relationship with the solar wind. It is found that (1) there is a positive correlation between the duskward component of the interplanetary magnetic field (IMF) and the duskward component of the geomagnetic field in the plasma sheet, with a proportionality constant of about 1.09. It indicates that the duskward component of the IMF can effectively penetrate into the near-Earth plasma sheet, and can be amplified by sunward convection in the corresponding region at geocentric distances of about 9∼13.4 Re; (2) the increase in the density or the dynamic pressure of the solar wind will generally lead to the increase in the density of the plasma sheet; (3) the ion thermal pressure in the near-Earth plasma sheet is significantly controlled by the dynamic pressure of solar wind; (4) under the northward IMF condition, the ion temperature and ion thermal pressure in the plasma sheet decrease as the solar wind speed increases. This feature indicates that plasmas in the near-Earth plasma sheet can come from the magnetosheath through the LLBL. Northward IMF is one important condition for the transport of the cold plasmas of the magnetosheath into the plasma sheet through the LLBL, and fast solar wind will enhance such a transport process.

Effect of solar wind variation on low‐energy O+ populations in the magnetosphere during geomagnetic storms: FAST observations

“…The results revealed that the particle pressure and the total pressure of the plasma sheet are strongly correlated with the ram pressure of the solar wind, with coefficients of 0.84 and 0.85, respectively. Recently, Double Star (TC‐1) observations [ Yan et al , 2005] also reported the same results, showing that the solar wind dynamic pressure significantly controls the ion thermal pressure in the near‐earth plasma sheet. Note that their studies did not consider the ion species.…”

“…In the previous studies, the following two processes have been considered as mechanisms for changing the ion population in the magnetosphere. One is that solar wind conditions control the variation of the plasma sheet properties [ Borovsky et al , 1998; Thomsen et al , 1998; Yan et al , 2005], and another is that solar wind conditions control the ionospheric ion outflow [ Moore et al , 1999; Elliott et al , 2001; Cully et al , 2003]. Borovsky et al [1998] statistically studied the coupling of the plasma sheet to the solar wind using the ISEE‐2 data.…”

Kelvin‐Helmholtz vortices observed by THEMIS at the duskside of the magnetopause under southward interplanetary magnetic field

“…In addition, Faganello et al [2012] showed another type of the vortex-induced reconnection in 3-D. Hasegawa et al [2009] revisited the Cluster event of rolled-up K-H vortices shown in Hasegawa et al [2004] and found the evidence of the associated reconnection near the rolled-up interval. Some models or statistical studies presented that during northward IMF, the solar wind could be transported into magnetosphere through the LLBL caused by the KHI [Fujimoto et al, 1997;Fairfield et al, 2000;Tsyganenko and Mukai, 2003;Yan et al, 2005]. As for the single point observation of rolled-up vortices, the criteria were established [Hasegawa et al, 2006] to identify the rolled-up K-H vortices and the solar wind entry into the magnetosphere.…”

Empirical Modeling of the Equatorward Boundary of Auroral Precipitation Using DMSP and DE 2

“…Regression models parameterized by B Y in addition to AE 3.5 or [dΦ MP /d t ] 5.0 , calculated separately for each hemisphere, do not perform any better. Although this is not the case for the polar cap or other precipitation boundaries, and the convection pattern in general, the equatorward edge of electron precipitation does not appear to vary with B Y , despite the influence B Y has on the inner magnetosphere (e.g., Matsui et al, ; Yan et al, ). This was confirmed through manual inspection of data plots similar to Figure , as well as the diminished efficacy of models parameterized by (AE, B Y ) and (dΦ MP /d t , B Y ) shown in Table , regardless of the parameters used in the weighted average of B Y .…”