Characteristics of Field Aligned Poynting Flux of Pc5 ULF Wave Based on Arase Measurements
Journal Article
Overview
abstract
Abstract; ; Ultra‐low frequency (ULF) waves play a critical role in energy transport within the magnetosphere‐ionosphere (M‐I) coupling system. Using approximately 7‐years of Arase satellite observations, we perform a comprehensive statistical analysis of the field aligned Poynting flux () in the Pc5 band in the inner magnetosphere. A pronounced enhancement in at higher latitudes is consistent with the trend inferred from the product of electric and magnetic wave amplitudes modeled by Cummings et al. (1969),; https://doi.org/10.1029/ja074i003p00778; . Comparison between inward and outward fluxes reveals a net energy flux toward the ionosphere, indicating energy dissipation in the ionosphere. To understand the cause of this net energy flux, a simplified model illustrates how the phase difference between electric and magnetic fields () affects net , suggesting that phase shifts, likely induced by ionospheric dissipation, play a key role in modulating . Latitudinal profiles of and for poloidal and toroidal modes at 6.82 mHz within; L; = 5.5–6.5 further demonstrate this effect of on . The magnetic local time dependence of shows pronounced day‐night asymmetry at higher latitudes, with stronger fluxes on the nightside, consistent with variations in ionospheric conductance. Finally, the latitudinal distribution of under varying geomagnetic activity conditions exhibits systematic enhancements with increasing; Kp; , particularly at higher latitudes. These results provide insights into the dynamics of energy dissipation and transport within the M‐I coupling system.;
