Monday, February 20, 2017

quiet, short, cloudy night

A short night tonight, with pretty solid cloud cover over Venetie for all of the evening.  The other mission took the opportunity to resolve a few technical issues, and we all left an hour early, a welcome respite after staying 2 extra hours (until 3am) 2 days ago, and 1 extra (until 2am) yesterday.

The composite imagery put together by the UAF group is now posted publicly at
at the moment it's pretty cloudy across Alaska but when the skies are clear and the aurora is active, it shows beautiful images of the auroral oval stretching across Alaska.

We spent much time this evening discussing the magnetometer traces that you can see at
If you choose Kaktovik, Toolik, Ft Yukon, Poker, and Eagle;  24 (or 6)  hours, 250 nT in the right hand column, you will see the display that we mostly use.  This shows the magnetic signatures as a function of latitude (Kaktovik is on the North Coast, down to Poker where we are, and Eagle a bit to the east).  The auroral activity is accompanied by horizontal currents.  A current is accompanied by a magnetic signature.  So this gives us a metric for the intensity of the aurora.  In the evening sector (during our window) the electrojet is predominantly westward.  A westward current over your head would be measured as a southward magnetic deflection on the ground (remember Ampere's law from your E&M course;  put your thumb along the current and your fingers wrap the magnetic field), so we are looking for the horizontal (H, red) trace to have sudden excursions downward.  We'd really like those to be a few hundred nT, for perhaps 10-20 minutes.  What we've seen in the last few days have been smaller, periodic "blippies" as we have been calling them.

We'll be hoping for some clear skies in the next few days as a large snowstorm is bearing down on us later in the week.

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