12-15 July 2011
Saint George Hotel
Africa/Johannesburg timezone
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Pc3 pulsations during low density events

Presented by Mr. Stefan LOTZ on 15 Jul 2011 from 09:15 to 09:30
Type: Oral Presentation
Session: APSS
Track: Track D2 - Space Science


<p>We study the generation of Pc3 geomagnetic pulsations (22 – 100 mHz) measured at Tihany, Hungary during intervals of very low solar wind (SW) proton density (low density events - LDE’s) when Np ~ 1/cc. We know the main SW based drivers of Pc3's are SW velocity and interplanetary magnetic field (IMF) direction. However, it is observed that under very low SW density pulsation activity measured on the ground is paused, regardless of otherwise favourable conditions. A simple statistical study is performed to show the dependence of pulsation activity on Np, and we estimate a threshold Np, below which pulsations cease. Furthermore we use the growth rate of the ion beam instability, that generates the ULF waves upstream of the bow shock (which drive Pc3's), to explain the observed dependence of Pc3 pulsations on solar wind density.

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Room: Acro2

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