Global model of plasmaspheric hiss from multiple satellite observations
We present a global model of plasmaspheric hiss, using data from eight satellites, extending the coverage and improving the statistics of existing models. We use geomagnetic activity dependent templates to separate plasmaspheric hiss from chorus. In the region 22-14 MLT the boundary between plasmaspheric hiss and chorus moves to lower L* values with increasing geomagnetic activity. The average wave intensity of plasmaspheric hiss is largest on the dayside and increases with increasing geomagnetic activity from midnight through dawn to dusk. Plasmaspheric hiss is most intense and spatially extended in the 200-500 Hz frequency band during active conditions, 400 <AE< 750 nT, with an average intensity of 1128 pT2 in the region 05-17 MLT from 1.5 <L*< 3.5. In the pre-noon sector, waves in the 100-200 Hz frequency band peak near the magnetic equator and decrease in intensity with increasing magnetic latitude, inconsistent with a source from chorus outside the plasmapause, but more consistent with local amplification by substorm-injected electrons. At higher frequencies the average wave intensities in this sector exhibit two peaks, one near the magnetic equator and one at high latitudes, 45o < |λm| < 60o, with a minimum at intermediate latitudes, 30o < |λm| < 40o, consistent with a source from chorus outside the plasmapause. In the pre-midnight sector, the intensity of plasmaspheric hiss in the frequency range 50-1000 Hz decreases with increasing geomagnetic activity. The source of this weak pre-midnight plasmaspheric hiss is likely to be chorus at larger L* in the post-noon sector that enters that plasmasphere in the post-noon sector and subsequently propagates eastward in MLT.
|Year of Publication||
Journal of Geophysical Research: Space Physics