F2, TEP & Es-Linked Propagation South from FM18

    "Dave, why did you write "No Es Noted" after some of the non-transequatorial openings & "Typical Morning F2" after others?"

Answer: Because while I believe they are all the result of propagation via the F2 layer of the ionosphere, based on the time of day it is also likely that different mechanisms are responsible for producing the ionization. "Typical morning F2" denotes the common F2 openings from W3 to Northern South America during the fall & winter solar peak years, which usually begin about 1300-1400z and sometimes last until 1700z. These openings usually begin to the Southeast (e.g. PY0FF/b) and follow the sun West, the last wisps of a dying HC8GR/b signaling their demise. The path geometry during these openings is often indicative of more Northerly ionization -signals often go over my head- and the geography involved often makes me wish for a greater colonization of Amazonia by Brazilian 6 meter ops. Propagation prognosticators agree. These are "pure" F2 openings.
    Openings occurring after 1600-1700z, which often happen closer to the equinoxes, are different in a number of respects. Path distances are always greater than the earlier openings, and the openings themselves are usually widespread, at least on the Northern end of the path. They are much less dependant on high solar flux numbers. In addition, while trans-equatorial QSOs are not always made during them, they are very often accompanied by propagation indicators (such as CE Music) indicative of a viable (or close-to-viable) TEP path, with a high level of ionization near the "tilt" region of the equatorial bulge. Interestingly, though they are closer, cluster reports indicate stations located within the TEP zone also have propagation. These openings sometimes generate dispute: Are they E-linked F2 openings on the Northern end of the path, or strictly "pure" F2? Suffice it to say that, bar a demonstrated Es link (or strong backscatter) stations within the Northern portions of the TEP zone are never heard here during these openings. I can often sit back & listen to the DX work W stations all over the Country and only hear the DX side of the QSOs. Thus, absent the specter of a humongous, unmoving, gargantuan Es cloud providing a linkup to the entire United States, I am confident they are strictly a product of F2-linked TEP or "pure" (unlinked) TEP, but for the skeptical "No Es Noted" is provided.

    "Why did you include African propagation in this list?"

Answer: Because propagation to the lower reaches of Africa crossing over the geomagnetic equator likely utilizes the same mechanisms as typical TEP to South America, and trust me, it is most definitely NOT "multi-hop" F2. TEP over this path entails a traditional East-West F2 opening over the Atlantic on the North side of the geomagnetic equator that in turn links up with African TEP. Note that the time of year these openings occur is right for TEP, and that on the DX end of the path it is also the correct time of day (local time). Moreover, a lack of mid-path signals (indicative of TEP propagation) provides further evidence. Though it is impossible to document this over water paths to islands such as ZD7, it is very possible to do so over large land masses such as Africa. Indeed, never once have I experienced a simultaneous opening to, say, Malawi, and other areas in Africa along the same path (such as Gabon). Moreover, consider signal strength & quality. Classic TEP flutter often accompanies these openings, and at other times the openings are unbelievably strong. Arguments claiming these openings are "multi-hop" F2 conveniently ignore serious path loss & multipath scatter that must occur at each ground reflection point, and offer no explanation for the sometimes amazing strength of low power African beacons. A TEP propagation model accounts for this easily- the signals only reach earth on the ends of the path.

    "Who cares about this Dave, and who really cares what you think about it anyway?"

Answer: Good question. My Domestic Relations professor in law school (a Circuit Court Judge) asked this rhetorically to me once, too, though that was over another matter. Essentially, nobody really cares but me and you, or obviously you wouldn't bother reading this. Simply put, I find that conventional descriptions of 50MHz propagation often fail to match up with what I have experienced on the band from my location, and thus they need to be rethought. Additionally, when I started out on the band I really had little understanding of how it all works, so I hope you find the analysis useful. If my experience doesn't match yours, or in light of my data you still disagree outright, great- the point is you thought about it.