So the A index is 27 and the K is 7. That's pretty bad right? See below. Lots of red. Well maybe not so bad in the tropics. This morning I could hear EA5JZ working a VK on 20 meter SSB. And yesterday morning I worked a very strong VK3XXY, also on 20 meter SSB. I note that the Space Weather Center warns (above) of "HF communication degradation at higher latitudes." So maybe my location at 18 degrees north explains the openings.
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Taking a quick look at the Aurora Forecast (https://www.swpc.noaa.gov/communities/aurora-dashboard-experimental) shows Au tonight (30 Sept) for the northern latitudes. For example, my relatives in Potsdam, NY (44.7° N) should be in for Northern Lights tonight with crystal clear skies (39F!). So, yes Bill, I think you are seeing the benefit of 18° N. Here at 40° N, it's poor propagation and probably no light show tonight.
ReplyDeleteMaybe Jimmie Buffet had it right with "Changes in Latitudes, Changes in Attitudes"?--73!
Ionospheric physics person here. The tropics where N2CQR is now are low enough in magnetic latitude (18N is about 33 degrees N magnetic) that you have to drive the system super hard - like Kp = 9 - to get serious geomagnetic storm induced disturbances in the local area. The equator does get chopped up with irregularities due to mechanisms like the equatorial fountain enhancement and spread F (no space here for explanations of those), so if you have transequatorial paths say from the DR to Argentina or something you might see trouble. But I would not have expected much to happen in the tropics on other kinds of paths. FYI, the HF comm degradation at high latitudes is most likely dayside enhancements in the D region from precipitation of energetic particles - D region is highly absorptive, which is why e.g. AM radio propagation is so different day vs. night under any condition (absorption!). However, that precipitation is not going to be a factor at low to mid-latitudes unless we get an extremely strong storm - nothing like Kp=7.
ReplyDeleteThanks Mike and Phil. This just proves that life is unfair. If this were a contest weekend, and if I were a contester, I could do well while northerners suffer.
ReplyDelete73 Bill N2CQR (back in the north now)
I also highly recommend examining trends in the maximum usable frequency (MUF) from Andrew Rowland KC2G's real time updating website. This uses data from worldwide ionosondes (colored circles on the map) with interpolations between the points based on the International Reference Ionosphere empirical model (IRI). Unfortunately, international data restrictions mean there are far fewer points now to drive the map, but it is still quite illustrative. Maximum Usable Frequency is a formula derived from the local frequency cutoff in the F region of the ionosphere, where the density peaks (and you can see that from KC2G's "f0F2" map if you click on that), and attempts to measure the highest frequency that will work for low angle / long path HF propagation. https://prop.kc2g.com
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