Orientation of Auroral Oval

[Guest taffski51]

Greetings all from a newbie.

 

A question popped  into my head this morning, which I'm sure could be answered with enough analysis of previous data.

 

To save myself the trouble I thought that maybe one of you learned folk know the answer already.

 

Is the orientation of the auroral oval's major axis dependent on:

 

a) the meridian facing the solar wind when it reaches the Earth;

 

b) the strength of the solar wind when it reaches the Earth;

 

c) the tilt of the earth relative to the Sun when the solar wind reaches the Earth, i.e. the date;

 

d) the present position of the Earth's Magnetic Poles;

 

e) a combination of one or more of the above;

 

or is it dependent on some other factors, or indeed completely arbitrary (which I doubt)?

 

Many thanks for any guidance.

 

Tony

[Vancanneyt Sander]

the orientation of the oval is pointing away from the position of the Sun. See the auroral oval model. So the oval is at it's biggest extent at 180° from solar noon.

Besides that we have on earth a magnetic north- and southpole, this is different from the geographic north- and southpole. So we have magnetic latitudes that stretch out a bit more south on the side of America (see the KP maps on the website)

So that was the standard auroral oval. The oval expands and shrinks according to the geomagnetic conditions. So when a CME hits and a geomagnetic storm is generated, the oval will expand to more Southern regions, if the geomagnetioc conditions get back to quiet levels the oval shrinks

[Marcel de Bont]

Just to add on this: 

 

c) the tilt of the earth relative to the Sun when the solar wind reaches the Earth, i.e. the date;

It is widely believed that in the period around the equinox, geomagnetic disturbances can be slightly more more intense than on other times. There is as far as I know not yet a solid scientific explanation for this phenomenon.