[600MRG] TA/TP wspr correlating to phases of the moon? TP around equinox.

[James Hollander]

Below, see more-detailed reasoning underlying my 9/13 discussion of equinox. 
 
73,  Jim H   W5EST 

POSSIBLE EQUINOX TP EFFECT?    REASONING. 

    An “equinox effect”hypothesis #4A suggests a modest trans-equatorial TP peak (overall path lossminimum) around equinoxes.  (This wouldnot apply to single-hemisphere TA or TP.)  I assume that the most critical parts of the N.America/VK-ZLpath for understanding path loss are at each end of the path where initialsignal takeoff and signal arrival via the D-layer occur.  Because of the long length of the TP pathfrom N. America across many time zones, VK-ZL stations face opportunity window conditionstimed not long after sunset when D-layer absorption may still be subsiding. Conversely,the corresponding opportunity window conditions timed before sunrise at N.America stations need to be as favorable as possible for N.America/VK-ZL TP tooccur.

    A pathloss minimum favoring TP success could arise from some kind of seasonalvariation in the path losses so that they add more favorably around equinoxfrom the D-layer conditions at takeoff and arrival than at other times. Symmetriesmay arise as a function of 1) departures of given dates from equinox and 2) oppositeseasons in Earth’s southern vs. northern hemisphere.  Until credible wspr SNR evidence is shownotherwise, I assume a noisy time symmetry of TP SNR by date-difference with respect to equinoxesbecause of the physical symmetry of the orientations of the tilted earth withrespect to the sun over an entire year or orbit of Earth around the sun. Also,much of the continental USA and southern Canada lie at north latitudes aboutequal to corresponding south latitudes in Australia and New Zealand.  (This noisy time symmetry may also have some “lunarmodulation” on it due to the weekly quarters of the moon.)

     Since equinoxoccurs on the same two dates all over the Earth, any other given date issymmetric in its date-difference from southern vs. northern hemisphere equinox.  If takeoff/arrivalpath losses are nonlinear with respect to day-of-the-year and symmetric withrespect to latitude, the path loss sum can indeed have a minimum at theequinoxes.  

     Some inferencescan be drawn at this point.  Receptionexperience on 630m indicates that trans-equatorial TP is better in mid-Auguston.  That means the overall path loss sumacross opposite hemispheres has indeed decreased from its value around summersolstice.  That means that the TP half-path loss in a given worldhemisphere in mid-summer exceeds the TP half-path loss in mid-winter in that hemisphere (and in mid-winter in the opposite hemisphere).  Also, physical continuity demands that the change in average path loss of each TPhalf-path loss in that hemisphere be nearly linearin the one week interval before and after equinox, and that the variationin contribution to path losses compared to each other on opposite north/southlatitudes must be symmetric with respectto date relative to equinox.  

      Fora visualization aid, make a “polar graph.” By polar graph I mean a graph thatlooks like an antenna pattern graph.  Butthis polar graph puts days representing daysof the year (instead of azimuths for an antenna pattern) around a largecircle.  Enter June 20 at the top of adiameter vertically through the circle, and December 20 at the bottom.  Put the March 20 equinox at left of ahorizontal diameter through the circle and the September 20 equinox at itsright.  In the polar graph, any point hasa radial distance from the center.  That radialdistance represents path loss.  A linefrom the center of the circle though the point makes a line that intersects thecircle at a corresponding day of the year. 

     The path loss of onehalf-path—the half of the TP path in the northern hemisphere--looks like afirst roughly-circular loop drawn inside the polar graph circle with its loopcenter displaced upward from the center of the polar plot toward the summersolstice.  This is because northernhemisphere path loss is higher in the summer and lower in winter.  For the southern hemisphere, draw an upside-down second roughly-circular loopwith its center displaced symmetrically downward from the center of the polar graphcircle.  This is because southern hemisphere path loss is higher in S. hemisphere  summer (when N. hemisphere is in winter) and lower in S. hemisphere winter (when N. hemisphere is in summer). 

     For the entire TPpath, however, its total trans-equatorialTP path loss is the sum of the path loss in the northern hemisphere part of thepath and the path loss in the southern hemisphere part of the path. The sumof the path losses represented by these two circles for every given date in theyear forms a fat figure-eight or fat-hourglass shape.  The shape has a large path loss hourglass“top” in in a range of dates centered on summer solstice and an equally-largepath loss hourglass “bottom” in a range of dates centered on winter solstice.  With greater departure from solstices the TPpath loss diminishes somewhat—enough to support TP occurrences as the 630mcommunity has already observed.  At thehourglass “waist” around equinoxes, the path loss should be diminished even alittle more.  

   So far this year, abunching of TA/TP occurrences has occurred at the lunar quarter-phases (first,full, third, new) of the moon.  As weapproach September 20 equinox, a few more TP occurrences are occurring inbetween the quarter phases.  The extra TPoccurrences may be arising from favorable conditions of low path loss at the hourglass“waist” around equinoxes.  

     Lately, 630mfolks have noted that the increases in solar flux index and geomagnetic K indexhave not so far had much effect on 630m conditions.  We shall see whether this continues to be thecase.  However, this lack of effect sofar is entirely consistent with the “fat hourglass” trans-equatorial TP picturedescribed here. 

    Let us then picture a yearly “fat hourglass”polar graph having a modest, but not insignificant, weekly periodic lunarvariation (corrugation) superimposed on the fat hourglass all the way around itsperiphery.  This variation is only somewhatcluttered with daily random SNR variations so that the TP threshold can stillbe surmounted mostly at the four quarter phases of the moon in the favorable 12 week ranges representing a shallow,broad and corrugated trough in TP path loss centered at each equinox.  The TP pathloss sum has this shallow, broad trough in TP path loss which is entered inAugust and exited in October and similarly entered in February and exited inApril.  

     Furthermore, in an approximately3 week range centered on each equinox,a somewhat-even-more favorable, near-minimum path loss may occur for N.America/VK-ZL TP events and perhaps even an occasional UK-EU/VK-ZL event.  Such TP successes during this near-equinoxmoment may somewhat obscure the lunar quarterly bunches of TP events so farseen.  In different years, thequarter-phase of the moon may or may not coincide with equinox, and dailyrandom variations are present, so this “equinox effect” is an approximateconcept.  Even so, such an equinox effectis likely to subside and we will likely return to lunar quarterly bunches of TPevents after roughly October 1.

    By contrast, asingle-hemisphere TA/TP path loss sum will follow only that one roughly-circularpath loss loop pertaining to the corresponding world hemisphere.  The applicable path loss loop is displaced justone way upward or one way downward in the polar graph and lacks the fat hourglassshape.  That is why N. America/UK-EU TAcan be expected to improve and become more regular as the fall progresses.  The bunching of TA according to weekly lunarquarters may become increasingly obscured for such TA in the fall.   We will see if the bunching of TA accordingto weekly lunar quarters returns around mid-March or the beginning of April,2015.
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