资源环境科技发展态势分析平台

We show that broadband low-frequency Alfvenic field variations observed in the inner-magnetosphere from the Van Allen Probes during geomagnetically disturbed intervals are composed of multiscale current sheets, current filaments, flow shears, and vortices. These observations pertain to spacecraft frame frequencies (f(sc)) over the range 0.1 < f(sc) < 10 Hz and correspond to structure advected over the spacecraft on scales (lambda) over the range 0.1 less than or similar to lambda/rho(i) less than or similar to 10. where rho(i) is the average ion gyroradius. The topology of the current and flow is derived via time domain and spectral approaches adapted for the interpretation of advected structure. The results reveal the action of magnetic and convective nonlinearities in the generation of broadband Alfvenic fluctuations prevalent in the inner magnetosphere during active times. The observed current filamentation and rotational vorticity is suggestive of how broadband Alfvenic field variations on kinetic scales are driven and support geophysically significant particle acceleration in the inner magnetosphere.