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Abstract We explore the characteristics of EMIC waves generated in a non‐dipole, compressed magnetic field at the minimum of the magnetic field. We conducted 2D full‐wave simulations using the Petra‐M code, focusing on a compressed magnetic field in the outer dayside magnetosphere for a range ofLvalues . By comparing the simulation results with MMS observations, we aim to understand how the observed wave characteristics are affected by a shifting source region across different L‐shells. Our findings indicate that the direction of the Poynting vector systematically changes depending on the local source location of the wave, which is consistent with the observations. EMIC waves propagate along the magnetic field line and reach both the northern and southern hemispheres; however, there is a notable difference in the power of EMIC waves between the two hemispheres, indicating seasonal asymmetries in their occurrence. 

Abstract Foreshock transient (FT) events are frequently observed phenomena that are generated by discontinuities in the solar wind. These transient events are known to trigger global‐scale magnetic field perturbations (e.g., ULF waves). We report a series of FT events observed by the Magnetospheric Multiscale mission in the upstream bow shock region under quiet solar wind conditions. During the event, ground magnetometers observed significant Pc1 wave activity as well as magnetic impulse events in both hemispheres. Ground Pc1 wave observations show ∼8 min time delay (with some time differences) from each FT event which is observed at the bow shock. We also find that the ground Pc1 waves are observed earlier in the northern hemisphere compared to the southern hemisphere. The observation time difference between the hemispheres implies that the source region of the wave is the off‐equatorial region. 

Abstract In the present study, we explore the observational characteristics of Electromagnetic Ion Cyclotron (EMIC) wave propagation from the source region to the ground. We use magnetometers aboard Geostationary Operational Environment Satellite (GOES) 13, the geosynchronous orbit satellite at 75°W, and at Sanikiluaq ground station (SNK, 79.14°W and 56.32°N in geographic coordinates, andL ∼ 6.0 in a dipole magnetic field) which is located in northern Canada. Using these magnetically conjugate observatories, simultaneous EMIC wave observations are carried out. We found a total of 295 coincident and 248 non‐coincident EMIC wave events between GOES 13 and the SNK station. Our statistical analysis reveals that the coincident events are predominantly observed on the dayside. The wave normal angles are slightly higher for the non‐coincident events than for coincident events. However, the coincidence of the waves is mostly governed by the intensity and duration of the wave. This is confirmed by the geomagnetic environment which shows higher auroral electrojet (AE) and Kp indices for the coincident events. We also found that some events show high‐frequency (f > 0.4 Hz) wave filtering. The statistics of the high‐frequency filtered and non‐filtered wave events show that there are clear magnetic local time (MLT) and F10.7 index differences between the two groups, as well as in ionospheric electron density measurements. In addition, we also found differences in the wave properties which possibly indicate that the propagation in the magnetosphere also plays an important role in the wave filtering.