Monday 6 June 2016

Deceptive Sun


A quick glance at Sunday's sun reveals a spotless environment, something we will likely be seeing more often in the years to come as the Solar Minimum arrives around 2020. The last minimum in 2009 saw a total of 260 days of spotless suns and long periods of very little geomagnetic activity.

Incredibly, during the minimum in the 28 year period between 1672 and 1699 there were 50 sunspots total. That's not a week or a month but two 11 year cycles worth. The normal expectation would be 40,000 - 50,000 spots within a 28-year period.

But the present, apparently quiet-looking sun, is not all as it appears as a look at today's satellite data and magnetometer readings indicate we are in the midst of a pretty good disturbance, driving the planetary K-index to level 5.

The source of the disturbance, as is often the case when the sun is not flaring, is a coronal hole stream ... CH738 to be precise, rotating into a geoeffective position once again after causing a similar disturbance to our geomagnetic field one month ago on its previous rotation. The large hole is the dark region approaching the right limb.

Back in the early 30's when amateurs and professionals were starting to draw links between radio propagation and sunspot activity, there must have been a lot of head-scratching when propagation disturbances arose from apparently quiet-looking suns, similar to what is happening at present.

With the vast array of solar instrumentation available to us online, much of the mystery involving propagation has been removed, making the tracking and even the predicting of geomagnetic activity, very much easier nowadays.

Kiruna Magnetometer:

From my location on the west coast of North America, my main 6m interest over the past several summer seasons has been focused on the short-lived and exciting sporadic-e openings over the pole to Europe ... but today's sun is not helping. Most of these fleeting openings seem to require undisturbed fields in the polar regions ... geomagnetic quiet. Once CH738 rotates out of view, hopefully the polar activity will subside and maybe, just maybe, the magical 6m polar path to Europe will tease us once again.

The July 8th, 2014 magic - West Coast to Europe on 6m

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