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[KA2FIR]

When do they subside?

[W1VT]

https://www.sws.bom.gov.au/Educational/2/1/5
At times of high solar activity, geomagnetic storms are generally the result of Coronal Mass Ejections (CMEs) intersecting the Earth's orbit, but at times of low solar activity, coronal holes are the most common source of geomagnetic storms. Because coronal holes can last for several months, it is often possible to predict the occurrence of this type of geomagnetic disturbance, as the high speed stream sweeps past the Earth with each solar rotation (like a rotating garden sprinkler).

[WA8NVW]

They rotate around the surface of the sun.  And they tend to return every 28 days, which is the rotational period of the solar disk.  Larger holes do tend to last more than one rotation.

[KA2FIR]

From what I read their frequency increases as we approach solar minimum. At what point in the solar cycle will Coronal Holes become less frequent and be replaced by CME's, Flares, etc?

Mike

[W1VT]

http://parkersolarprobe.jhuapl.edu/

Parker Solar Probe will swoop to within 4 million miles of the sun's surface, facing heat and radiation like no spacecraft before it. Launching in 2018, Parker Solar Probe will provide new data on solar activity and make critical contributions to our ability to forecast major space-weather events that impact life on Earth.

In order to unlock the mysteries of the corona, but also to protect a society that is increasingly dependent on technology from the threats of space weather, we will send Parker Solar Probe to touch the Sun.

[KC6RWI]

Good read. really its a better read than science "fiction". Its mind boggling the sun, and pretty amazing that we have a probe going at over 200,000 mph that gets near it. I can't only be that by design the sun can throw billion of tons of material at the earth and the earth repels it. I think you know where I going with this.