[600MRG] Ionosphere Patch Mapping: Part 3

[James Hollander]

Please add your words of wisdom whether this ionosphere patch mapping method makes sense or how to improve it.  The info involves a July 30, 2015, loss and reacquisition of XIQ decodes at  SWLK9EN61,  WB8ILI,  WA3TTS/2.   Thanks to Ken, SWLK9EN61, for asking me to take time to really think about the WSPR data from that night.        73,  Jim  H   W5EST             


   IONOSPHERE  PATCH  MAPPING  (continued)
     How big was the patch?  About 300 miles across, I'd guesstimate. 
     The southern (S) boundary of the patch was moving north of NE. So, when the NE front of the patch shut off XIQ, considerable time had to elapse before the S boundary would arrive at 1-hop path midpoints and start releasing XIQ's signal ray to reach TTS, K, and finally ILI. 
     That means the patch S boundary was probably in southern Arkansas when the NE patch front through Mountain Grove, MO, shut off XIQ from K at 0252z.  [0.62mi/km x 290km/hr x (88=0420-0252)/60].  The NE patch front boundary would have intersected the S boundary in NW Mississippi. 
     Can we say anything about a western part of the patch? Very little, because no stations were receiving in Nebraska and the Dakotas.  However, W0JW in Iowa began receiving XIQ at 0412z. Halfway 1-hop between XIQ and W0JW lies at the SE corner of Kansas on that quite-short 600 mile path.  A straight-line southern boundary for the patch does not explain this 0412z decode at W0JW.  To explain it, I looked carefully at the map points  and conclude that a curved southern boundary for the patch gradually bent WNW from S MO toward SE KS.  Although XIQ was W0JW's first decode of anybody that night, XIQ was closest and the large NNE-moving patch was probably extensive enough to block W0JW's reception of XIQ earlier that evening.     

    CONCLUSIONS: A ionospheric  traveling wave disturbance acted like a patch obscuring XIQ from reception at SWLK9EN61, WB8ILI, and WA3TTS/2 for almost an hour in the very late evening July 29, 2015 (July 30 Zulu).  The times of loss and reacquisition of WSPR decodes at those three receiving stations strongly suggest the patch extended through S Arkansas to a corner in NW Mississippi and arched back to the NW overhead Mountain View, Missouri.  The patch moved approximately 370mph (166 m/sec, 600km/hr) in a direction somewhat N of NE. The NE patch front first dropped XIQ from SWLK9EN61 at 0252z and then simultaneously dropped XIQ from WB8ILI and from WA3TTS/2 24 minutes out.  After about an hour not receiving XIQ, the SSE side of the patch reached the 1-hop halfway points of XIQ's signal and released XIQ for reception first at WA3TTS/2 0412z, and then SWLK9EN61, and finally WB8ILI 14 minutes after WA3TTS/2.  Based on 0412z reception at W0JW, the patch was gradually curved into SE Kansas at the time.  Overall, the information on hand suggests the patch was about 300 miles across.
   (To discuss suggestions, limitations of the method, and further work needed please e-mail Jim H direct at mrsocion at aol.com . 73!)
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