[CQ-Contest] 40M open early for DX in CQWWCW

[donovanf at starpower.net]

Hi Tim, 


Congratulations, you've discovered some of the affects of low 
sunspot activity on DX contesting strategy. During the CQWW 
CW Contest those affects were compounded by the Earth 
directed affects of an unusually large and energetic solar coronal 
hole. 


One of the most pronounced phenomena of the night time 
ionosphere during fall and winter is the "mid-latitude trough" 
(Google that term for more detail). Its a region of significantly 
depleted total electron content (much reduced MUF) just 
southward of the northern hemisphere auroral zone. The 
trough occurs during about half of the fall and winter nights, 
and it strongly affects propagation on high latitude paths such 
as the short path from eastern north America to Europe and 
Japan. During about half of those fall and winter nights (those 
nights when the trough is active), the trough typically develops 
near sunset at its westward end and rapidly disappears at 
sunrise at its eastern end. 


http://www.qsl.net/kl7j/images/latitude%20variations.jpg 


Last weekend the night time auroral zone was pushed significantly 
southward by the affects of an unusually large and energetic 
earth-directed coronal hole that also pushed the mid-latitude 
trough directly over our north- Atlantic propagation paths to Europe 
and our high latitude short path to Japan. As a result, our best 40 
meter propagation to Europe occurred during north American 
daylight hours and after European sunrise. The mid-latitude 
trough significantly shortens the duration of 40 meter propagation 
to Europe and Japan for stations located at more northerly 
latitudes and somewhat less for stations at more southerly 
latitudes during those nights when the trough is active. 


Our very brief short path propagation from the mid-Atlantic 
states to Japan occurred near JA sunset (0730-0830Z). Soon 
after JA sunset our propagation to Japan was mostly via the skew 
path that propagates via the tilted ionosphere about 20 degrees 
south of the equator, Our east coast short path to Japan usually 
strongly redevelops near east coast sunrise, but the affects of the 
coronal hole significantly degraded our short path to JA. 


While the most pronounced affects of the trough are on 40 meter 
propagation, it also significantly shortens the duration of our 
openings to Europe and Japan on the higher bands, essentially 
terminating the openings near sunset at the eastern end of the 
paths during about half of the November through February nights 
when the trough is active. 


I ts a big mistake to consider 40 meters to be mostly a night time 
DX band near the bottom of the sunspot cycle. Daytime 40 
meter DX is significantly enhanced near the bottom of the 
sunspot cycle by the reduced daytime E-layer MUF which 
otherwise blankets the F layer during most daylight hours nearer 
the top of the sunspot cycle. As a result, DX propagation is 
possible on 40 meters during most daylight hours , especially for 
stations located at higher latitudes from November through early 
February. During those months daytime propagation is common 
from the northern east coast USA to northern Europe even at 
high noon. 


Close to the bottom of the sunspot cycle, both the short and long 
paths are strongly open from the East coast to Japan on 40 meters 
during many December and early January late afternoons from 
2130Z to about 2215Z. If you have a directive antenna, some 
JA stations can be worked on only one of those paths if they're 
also using a directive antenna. Without a directive antenna, 
some JA signals can be an unreadable blur of overlapping echos. 


True long paths from the USA to Japan (not skew paths) rarely 
exhibit scintillation affects that are usually observed on the short 
path because the long path propagates well away from the 
southern auroral zone during the southern latitude summer. 


73 
Frank 
W3LPL 



----- Original Message -----

From: "Tim Shoppa" <tshoppa at wmata.com> 
To: ve9aa at nbnet.nb.ca, cq-contest at contesting.com 
Sent: Tuesday, November 29, 2016 2:12:10 PM 
Subject: [CQ-Contest] 40M open early for DX in CQWWCW 

Mike VE9AA - 
You asked several good questions in CQ-Contest. 

Below are some of my thoughts on the ebb and flow of band choices in CQWW: 

>From the EU point of view, they can work most of the other EU's on 40M and 80M and 160M for points and mults. Here in NA, VE's only work W's and W's only work VE's for points. And even that is lopsided because the VE's have a lot more W's to work than W's have VE's to work. 

So the EU's are on 40M even before THEIR sunset. And it is that it is often advantageous (point wise) for a VE station to stay on 20M much later than a W, because the VE can run W's on 20M for points. 

The disturbed conditions on 40M after my sundown, caused a lot of us W1-W4's to figure out that it was much easier to go to 40M to work EU's way before our sundown rather than after. Also, because there was no chance of folks like me running JA on 15M like in solar max, we were not spending a lot of time running on 15M in the afternoon. 

The usual thought that 40M is a "darkness band" is not true, even in undisturbed conditions. It's very often for me to CQ on 40M in CWOps at 1300Z and get replies from VK's, even though both ends are in sunlight :). Occasionally I will be CQ'ing at 1300Z in the deepest of winter, and be picked up by skimmers in EU (especially GW8IZR who has the most incredible skimmer ears, maybe only met by that VK4 skimmer) even though it is local noon in EU. 

I had a handful of long-path JA callers on 40M in my afternoon while I thought I was CQ'ing for EU. The long path JA's sounded especially clear and unwobbly to me. Both ends were in sunlight. Usually I don't get long path JA callers until we are closer to winter solstice. 

I had a VERY HARD TIME running EU on either 40M or 80M, but no problem at all on 20M. This poor conditions on 40M/80M were very unusual for me. I'm guessing that 80% of my 20M QSO's were running, and that 80% of my 40M QSO's were S&P., and that's just unusual for me. 

Mike, you also asked why the EU's weren't chasing us on the skimmer spots. A very knowledgeable local shared with me, that in poor conditions the pipsqueak EU's who might chase skimmer spots rather than CQ, they don't stay up late working 40M, they're in bed, so there are many fewer to reply to my CQ's even if we could hear other. 

Tim N3QE 
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