Distribution of turbulent plasma in the magnetosphere estimated by the SWARM magnetic data.

Abstract:

LEO satellites observe the magnetic fluctuations with period from a few second to a few tens of seconds along their orbits in high-latitudes. It has been proposed that these are mainly caused by the spatial structures of the field-aligned currents(FACs). However, since LEO satellites before the SWARM were single, the studies still have theoretical assumptions.

In this study, at first, we will show that these fluctuations are the manifestations of the spatial structures of the FACs by using the data obtained by SWARM-satellites during initial two months.

Second, based on the above, we assume that these fluctuations mainly consist of the spatial variations, and apply spectral analysis to see the characteristics of the spatial structure of the FACs.

From the above analyses, we confirm that the fluctuations with period from about 2 second to about 30 second can be regarded as the manifestations of the spatial structure of FACs.

Then we project the area of fluctuations on the equatorial plane of magnetosphere, i.e., the plasma sheet, by using the Tsyganenko model, and estimate the characteristics of turbulence.

We will also show the relations between these turbulent region and the substorm phase etc.