Aurora Latitudes Question

[trebor]

I have been watching the aurora prediction/ activity charts such as this one http://www.swpc.noaa.gov/pmap/gif/pmapN.gif

for a long time now. I think I have noticed that the activity is very often lower than the 60 deg line of latitude over canada and

the US but it seldom gets to or passes this latitude over the UK.

my question is why? or have I imagined it has anybody else noticed it

any input welcome thanks

[Waveform]

I have been watching the aurora prediction/ activity charts such as this one http://www.swpc.noaa.gov/pmap/gif/pmapN.gif

for a long time now. I think I have noticed that the activity is very often lower than the 60 deg line of latitude over canada and

the US but it seldom gets to or passes this latitude over the UK.

my question is why? or have I imagined it has anybody else noticed it

any input welcome thanks

I'm not so sure that aural activity is and better over Canada at the same latitude.

Remember the Earth has a ~ 23° tilt. The solar disturbance will not target the exact North pole.

This is not a 'circular' pattern.

Also the earth rotates 'under' those graphic displays. So, if you observe them at, let's say 1:00pm local time as opposed to 3:00am local time the whole observing time will be biased or skewed.

It's just one of those things where the observance of local time will seem to appear to favor or not favor a certain event.

Just a thought. :lol:

[frogesque]

Can't remember where but I've seen a reference that suggests the auroral oval is somewhat distorted by the Eastern seaboard of the Canadian/American landmass. The idea seemed to be that the mineral content of the Earth's crust causes perturbations in the magnetic field. It also has to be remembered that the auroral oval follows the Earth's magnetic poles not the geographic north and south poles and this does favour Canada and Alaska rather than Northern Europe.

[trebor]

I'm not so sure that aural activity is and better over Canada at the same latitude.

Remember the Earth has a ~ 23° tilt. The solar disturbance will not target the exact North pole.

This is not a 'circular' pattern.

Also the earth rotates 'under' those graphic displays. So, if you observe them at, let's say 1:00pm local time as opposed to 3:00am local time the whole observing time will be biased or skewed.

It's just one of those things where the observance of local time will seem to appear to favor or not favor a certain event.

Just a thought. :lol:

I had thought about all the things you mention as possible causes but the problem is (and correct me if i'm wrong) that during the coarse of a year canada

doesn't go anywhere that the uk doesn't follow as far as tilt and possition relative to the pole/ auroral oval is concerned and I have very rarely seen northern lights

reported as far south as 60 degrees in the uk but I cant say the same for canada.

[Waveform]

I had thought about all the things you mention as possible causes but the problem is (and correct me if i'm wrong) that during the coarse of a year canada

doesn't go anywhere that the uk doesn't follow as far as tilt and possition relative to the pole/ auroral oval is concerned and I have very rarely seen northern lights

reported as far south as 60 degrees in the uk but I cant say the same for canada.

Hi trebor,

Yup, absolutely right, Canada does not go anywhere the UK goes.

However, remember the aura is an interaction of 'solar disturbances' with the earth's magnetic field.

The earth's magnetic field is a function of the iron and displacement of the earth's interior.

The magnetic north pole is not a constant but a variable.

Over the period of several years the magnetic north can travel several hundreds of kilometers, thus varying the location of aura.

I have the same problem as you. I live close to 45̊N, but observation of aura can greatly vary.

Thing is, what you see or don't see in aura is more attuned to several hundred kilometer under the earth than several hundred kilometers above.

Also, as frogesque pointed out, if the topography of the Eastern seaboard may be endowed with a higher ferrous mineral quantity (which I am not sure of) it would certainly account for then anomaly.

One last thing, Canada extends (or so they think) geographically to > 80̊ N. This puts it in league with Greenland and higher than Iceland.

Regardless, it would be nice to see more aura for here and you guys in the UK.