Until now it is still questionable whether ions are accelerated to energies above 100 keV in the near-Earth current sheet (CS), in the vicinity of a possible near-Earth neutral line. By using 11 years of 3-D energetic ion flux data for protons, helium, and oxygen (~150 keV-1 MeV) from the RAPID instrument on board Cluster 4, we statistically study the energetic ion acceleration by investigating ion anisotropies in the near-Earth magnetotail (À20 R E < X <À16 R E ). It is found that the earthward (tailward) anisotropy of the energetic (>150 keV) ions (protons, He + , and O + ) tend to become higher as the earthward (tailward) plasma bulk flows (measured by Cluster Ion Spectrometry experiment) become stronger. During such periods the presence of a strong acceleration source tailward (earthward) of Cluster spacecraft (S/C) is confirmed by the hardening energy spectra of the earthward (tailward) energetic ion flows. A good statistical correlation between tailward bulk flow, negative Bz, and the tailward anisotropy of energetic ions indicates that the strong ion acceleration might be related to a near-Earth reconnection, which occurred earthward of the Cluster S/C. The energetic ion anisotropies do not show a clear dependence on the AE index, which may indicate that the acceleration source(s) for the energetic ions could be spatially localized.

The response of Thellungiella (Thellungiella holophila) and Arabidopsis (Arabidopsis thaliana) callus to salt stress was investigated. The relative growth rate of Arabidopsis calli decreased with increased levels of NaCl. However, the relative growth rate of Thellungiella calli increased with higher levels of NaCl, reaching maximal growth at 100 mM NaCl, but then subsequently declined. A similar pattern of accumulation of proline, glycine betaine, and total flavonoid was observed; whereas, accumulation of treholase continued to increase with increasing NaCl levels in both Thellungiella and Arabidopsis calli. Overall, with increasing NaCl levels, accumulation of glycine betaine, total flavonoid, and treholase was higher in Thellungiella than in Arabidopsis calli; while, proline and sucrose contents were higher in Arabidopsis than in Thellungiella calli. These results indicated that compatible solutes were involved in the response of plant calli to salt stress, and that the halophyte Thellungiella and glycophyte Arabidopsis selected different compatible solutes to adapt to salt stress environments.

The auroral electrojet (AE) indices have widely been used in various fields of solar terrestrial physics since their introduction to the community. Recently, it has been reported that the AE indices do not, at times, properly monitor the auroral electrojets because as magnetic activity increases, they expand equatorward beyond the standard AE network, resulting in a serious underestimation of the auroral electrojet intensity. It is particularly the case during severe geomagnetic storms. To determine quantitatively the equatorial expansion of the auroral electrojets, we examined an extensive database obtained from the Alaska, International Monitor for Auroral Geomagnetic Effects (IMAGE), and Canadian Auroral Network for the OPEN Program Unified Study chain of magnetometers. These chains of magnetometers enable us to determine the latitude where the maximum current density of the auroral electrojet flows. It is generally understood that the center of the auroral electrojet tends to migrate equatorward with an increase in magnetic activity. We note, however, that there seems to be a lower limit particularly of the westward electrojet, ∼60° in corrected geomagnetic latitude, regardless of magnetic activity levels. The relative location of the westward electrojet with respect to the global auroral image taken from the Polar satellite is also examined. Contrary to the generally accepted notion, the auroral electrojets are found to be most intense not in the region of bright auroral luminosity but slightly poleward of it in less luminous region. The current center seems to be the region where both ionospheric conductivity and electric field become significantly high.

Energetic ion distributions in the near‐Earth plasma sheet can provide important information for understanding the entry of ions into the magnetosphere and their transportation, acceleration, and losses in the near‐Earth region. In this study, 11 years of energetic proton and oxygen observations (> ~274 keV) from Cluster/Research with Adaptive Particle Imaging Detectors were used to statistically study the energetic ion distributions in the near‐Earth region. The dawn‐dusk asymmetries of the distributions in three different regions (dayside magnetosphere, near‐Earth nightside plasma sheet, and tail plasma sheet) are examined in Northern and Southern Hemispheres. The results show that the energetic ion distributions are influenced by the dawn‐dusk interplanetary magnetic field (IMF) direction. The enhancement of ion intensity largely correlates with the location of the magnetic reconnection at the magnetopause. The results imply that substorm‐related acceleration processes in the magnetotail are not the only source of energetic ions in the dayside and the near‐Earth magnetosphere. Energetic ions delivered through reconnection at the magnetopause significantly affect the energetic ion population in the magnetosphere. We also believe that the influence of the dawn‐dusk IMF direction should not be neglected in models of the particle population in the magnetosphere.