Thanks, Frank, for the excellent explanation.
73,
Scott K9MA
On 11/26/2020 1:19 AM, donovanf@erols.com wrote:
Sunspot activity has increased dramatically over the last two months.
Most days this month have had multiple and more active sunspots
resulting in the solar flux index exceeding 100 for the first time since
September 2017. SFI is likely to remain above 100 during the CQWW
CW DX Contest and remain at 90 or above for at least another week.
But recall that both the sunspot number and the 2800 MHz solar flux
index are proxies for the the actual source of F layer ionization that cannot
be observed on the surface of the Earth: extreme ultraviolet radiation
We can't yet determine if this is a short term surge or a sustained
increase in sunspot activity. We'll have a better understanding in about
six months.
The first year of increased sunspot activity is a sweet spot in the solar cycle
because:
- increased extreme ultraviolet radiation starts to open the 10 meter band,
makes 15 meters more reliable including more frequent JA and long path openings
keeps 20 meters open later into the night and opens it well before sunrise
keeps the MUF into Europe above 7 MHz during most or all of the night
- coronal hole high speed streams that cause elevated K indices during
the declining years of the solar cycle and during solar minimum are
now less frequent and not as strong, keeping the K index consistently
low for about the next year.
- fast coronal mass ejections (fast CMEs) that cause much more severe
and more frequent geomagnetic disturbances won't start to occur
regularly until at least late next year.
- daytime D layer absorption that affects 160 and 80 meters much more
severely than 40 meters hasn't yet begun to increase significantly as
it will when we get closer to solar maximum
- E layer ionization ( not sporadic-E -- that's completely different) hasn't
yet begun to increase significantly. As we get closer to solar maximum
consistently higher E-layer MUFs will blanket 40 meter DX openings
until later in the afternoon.
Enjoy the ride especially this weekend in the CQWW CW DX Contest
73
Frank
W3LPL
----- Original Message -----
From: "Alfred Laun" <hs0zar@gmail.com>
To: "PVRC" <pvrc@mailman.qth.net>
Sent: Thursday, November 26, 2020 4:09:22 AM
Subject: [PVRC] Solar Cycle Rise
We are seeing the Solar Flux Index hit a daily peak of 104 already, even though
solar minimum is said to have been reached only 11 months ago in December 2019.
I thought this seems faster than it rose last time, so I went to
https://www.swpc.noaa.gov/products/solar-cycle-progression
to take a look at what happened just after the last minimum. According to that
chart, monthly average solar flux bottomed out at 65.7 in July of 2008. Monthly
average solar flux did not get to over 100 until March of 2011, or 32 months
later.
Granted, the last solar minimum began with an SFI about 2 points lower than
this latest minimum, but still, it looks to me like the rise is faster this
cycle.
Yes, there are complications, like the difference between actual daily values
and the smoothed daily values which are used to produce a visual curve that
doesn't jump all over the place. And what we have today are daily values, not
monthly values. But it still looks to me like things are moving along pretty
fast.
I am not a scientist, so I invite all of those interested to go to that site,
hover your mouse over the curve, and see what you come up with.
73, Fred, K3ZO
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Scott K9MA
k9ma@sdellington.us
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