The Solar Wind

The Solar Wind parameters are derived from the ACE satellite, this satellite is situated on 1/100 of the Sun - Earth distance. The measurements from the ACE satellite reach us in about an hour.

The Speed of the Solar Wind

The Speed of the solar wind is very important, if the speed is too low there will be no chances to see some aurora. The normal solar wind speed is around 300km/sec but increases when a coronal hole or CME shock (coronal mass ejection plasma cloud) arrives. Depending of the speed of impact the solar wind can jump to 500 or 700km/sec or even 1000km/sec.
For the Middle Latitudes a good speed is required and should be around 700km/sec, but it can also happen that aurora can form with lower speeds (depends on the strength of the Interplanetary Magnetic Field).
On the data plots you can easily see when a CME shock has arrived, the solar wind increases immediatly with sometimes several 100km/sec. When a shock arrives, it's time to look at the IMF parameters and the magnetometers. Keep in mind that when the shock arives at the ACE satellite it takes about an hour to reach earth. Below a good example of an arrival of a CME shock of 2006:

The Solar Wind Density

This parameter measures the proton density in the solar wind. The more protons in the solar wind, the more chances we get for an auroral display. The scale, used in the plots, is protones per cubic cm or p/cm³. A value above 50 is positive but is no garantee that we'll see the aurora. It often happens that at impact the density is high but then collapses to nearly zero, don't let it fool you.

<< Zurück zur vorherigen Seite