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Monday, December 17, 2007

Last night of operations -no blue skies here

Well tonight we are running the last experiment of this campaign (last UK EISCAT campaign ever?). Ionospheric conditions are good. A high-speed solar wind stream from a coronal hole (see image from Hinode, courtesy of has impinged on the Earth's atmosphere. This is driving increased energy transfer which is then released as auroral displays during substorms; large-scale reconfigurations of the Earth's magnetic field on the night-side, with associated particle transport and acceleration. Coronal holes usually rotate with a 27 day period (which is roughly the rotation period of the Sun). This one is rotating into view a day earlier with each rotation. This could be because the hole is closer to the polar regions than the equator and the Sun experiences a differential rotation.

The fast stream can be observed in data from the ACE satellite (I provide a snapshot since the on-line plots always update). See the high density (orange) that occurs at the same time that the magnetic field increases (white)? This is an example of a co-rotating interaction region, where the fast solar wind catches up with the slow wind compressing the interplanetary magnetic field. You can see the tail end of the last stream (yellow) that provided so much nice data for us last week (after the noise!).

So plenty of nice radar data tonight as those electrons and protons dive into the atmosphere, ionising as they go. No optics to look at unfortunately. It has been raining persistently for the past few days (wiping out much of the snow). Coupled with the time of year, we have been pretty much in the dark all day; that's generally how we feel when understanding decisions made by STFC come to think of it.

Anyway, STFC and the British government should love us; with the dark and the rain there has been absolutely no blues-skies research going on here for the past few days. Just how they seem to like it.

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