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Space Weather Update 18-Feb-2011

What Has Happened?


The magnetogram from Eskdalemuir Magnetic Observatory in the Scottish Borders showing the storm sudden commencement and following geomagnetic activity early on the 18th Feb. Image BGS (NERC).

The 3-hour estimated Ap index showing geomagnetic activity levels over the past week. Image BGS (NERC).


The anticipated arrival of a interplanetary coronal mass ejection (ICMA) that was associated with the largest solar flare in 4 years (X2.2 on 15th Feb) impacted the Earth's magnetic field at 01:30 UT this morning (18th Feb).

Having taken 3 days to travel from the Sun to the Earth, the interplanetary shock wave created a sudden impulse in the geomagnetic field known as a Storm Sudden Commencement (SSC). This was recorded at the BGS UK magnetic observatories and simultaneously at observatories around the world. At Eskdalemuir in the Scottish Borders the horizontal strength of the magnetic field changed suddenly by 27nT.

Since then the magnetic cloud following the shock, as measured by the ACE spacecraft, has been configured in such a way that restricts the transfer of energy from the ICME into the Earth's magnetic field. As such, the geomagnetic activity level following the SSC has so far been relatively weak.

This can still change,so the chance of displays of the Northern Lights (aurora borealis) remains higher than usual tonight.


See BBC Weather Forecasts for clear skies.

See BGS Real-time estimated Ap for global geomagnetic activity levels.

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