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1、PVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LASelected Topics in PropagationCarl Luetzelschwab K9LAPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAWhat Well Cover in This SessionAn Update on Cycle 24 Will it be an underachiever?Will it be an underachiever?The M-Factor Some theo
2、ry about one of the basic parameters of Some theory about one of the basic parameters of the ionospherethe ionosphereSunspots and Solar Flux During Cycle 23 An interesting anomaly not sure what it says yetAn interesting anomaly not sure what it says yetIonosphere-Ionosphere Modes Theres more than mu
3、lti-hop out thereTheres more than multi-hop out therePVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAAn Update on Cycle 24PVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LALatest DataminimumSmoothed 10.7 cm solar flux is still risingPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9,
4、2011 K9LALatest DataminimumPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAReview of the PredictionsThese are from the Solar Cycle 24 PredictionThese are from the Solar Cycle 24 PredictionPanel (NOAA, NASA, ISES, and other personnel)Panel (NOAA, NASA, ISES, and other personnel)1409090The L
5、atest PredictionThere may be an updated prediction (lower) from the Solar Cycle 24 Prediction PanelPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAMarshall Space Flight CenterSimilar prediction to Kane, “Similar prediction to Kane,
6、“Size of the coming solar cycle 24 based onSize of the coming solar cycle 24 based onOhls Precursor Method, final estimate”Ohls Precursor Method, final estimate”, Annales Geophysicae, July 2010, Annales Geophysicae, July 201059A lot of evidence pointing to small Cycle 24But . . . . . . .Not everyone
7、 agrees that Cycle 24 will be so smallRecent prediction in Solar PhysicsMaximum of 131 +/- 20Maximum in July 2012 +/- 4 monthsFrom R. S. Dabas and Kavita Sharma, Prediction of Cycle 24 Using Geomagnetic Precursors: Validation and Update, Solar Physics, Vol 266 No 2, pp 391-403, July 2010This would b
8、e good for the higher bands and for 6m F2If Cycle 24 is a small one, though, 6m F2 propagation will take the biggest hitThank goodness for summer E region propagationPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAPredictions in GeneralOver 60 predictions for Cycle 24Maximum smoothed sunsp
9、ot number from 40 to 185Common forecasting methodsStatistical methods: length of Cycle n correlated to maximum of Cycle n+1, maximum R12 correlated to minimum R12Generally gives low Cycle 24Geomagnetic precursor methods: Ap, aa, and number of magnetically disturbed days correlate to next maximumUnfo
10、rtunately can give widely varied answers depending on assumptionsPolar field precursor method: strength of Suns polar field correlates to next cycleGives small Cycle 24Solar dynamo method: the conveyor belt theoryUnfortunately can give widely varied answers depending on assumptionsSummary of forecas
11、ting methods from K. J. Li, et al, A brief review on the presentation of cycle 24, the first integrated solar cycle in the new millennium, Annales Geophysicae, 29, 341-348, 2011PVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LARecent NASA News “Researchers Crack the Mystery of the “Researche
12、rs Crack the Mystery of the Missing Sunspots”Missing Sunspots” Solar scientists claim theyve developed a Solar scientists claim theyve developed a new computer model of the suns interior new computer model of the suns interior that gets the physics right for all three that gets the physics right for
13、 all three aspects of the sunspot generation process -aspects of the sunspot generation process -the magnetic dynamo, the conveyor belt, the magnetic dynamo, the conveyor belt, and the buoyant evolution of sunspot and the buoyant evolution of sunspot magnetic fieldsmagnetic fields Maybe this will he
14、lp narrow down the range Maybe this will help narrow down the range of the forecasted maximum smoothed of the forecasted maximum smoothed sunspot numbersunspot numberPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAKeep an eye on NASA Headline News, http:/, Keep an eye on NASA Headline News
15、, http:/, http:/www.swpc.noaa.gov, and http:/http:/www.swpc.noaa.gov, and http:/http:/science.nasa.gov/science-news/science-at-nasa/2011/02mar_spotlesssun/http:/science.nasa.gov/science-news/science-at-nasa/2011/02mar_spotlesssun/ARRL DX CW and PHPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011
16、 K9LA1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 1 2 3 4 5 6 7 8FebMarIts headed in the right direction!ARRL DX CWARRL DX PHARRL DX CW and PHPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LARecent solar activity helped ARRL DX PH the mostARRL DX CWARRL DX PHre
17、d line is one-day running average1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 1 2 3 4 5 6 7 8FebMar28 MHz21 MHzPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAThe M-FactorNo, not this MPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAWhat Is The M-Fac
18、tor?The M-Factor (MUF factor) relates the MUF (maximum The M-Factor (MUF factor) relates the MUF (maximum useable frequency) to the critical frequencyuseable frequency) to the critical frequency MUF = M-Factor x Critical FrequencyMUF = M-Factor x Critical Frequency M-Factor and critical frequency (a
19、long with other parameters) are M-Factor and critical frequency (along with other parameters) are measured by ionosondesmeasured by ionosondesM-Factor is one over the sine of the angle between the M-Factor is one over the sine of the angle between the ray and the ionosphere ray and the ionosphere (a
20、lso known as the secant law as 1/sine = secant)(also known as the secant law as 1/sine = secant)sine of this angleIf the angle = 90o (vertically incident), then the M-Factor equals 1 and the MUF = the critical frequencyionospherePVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAApply It To T
21、he IonosphereionosphereEarthThus the M-Factor = 1 sine (1o) = 57 Wow if the critical frequency is 5 MHz, then the MUF would be 285 MHzWow if the critical frequency is 5 MHz, then the MUF would be 285 MHz But hold on the Earth-ionosphere system isnt flat its sphericalBut hold on the Earth-ionosphere
22、system isnt flat its spherical = 1o = 1oPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAThe Real Earth-Ionosphere SystemionosphereEarthheight now matters lets assume 300 kmNow the M-Factor = 1 sine (17.5o) = 3.3MUF for this F2 region scenario is about 3 times the critical frequency = 1o =
23、17.5oM-Factor vs Height and AnglePVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAThis calculation assumes specular (mirror-like) reflection over an infinitely short distance the real-world is refraction over a spherical distance height distance M-Factor100 km0 deg2243 km 10.1 deg5.75 deg13
24、89 km 11.3 deg5.110 deg 927 km 14.2 deg4.125 deg 408 km 26.8 deg2.2200 km0 deg3152 km 14.2 deg4.15 deg2226 km 15.0 deg3.910 deg1620 km 17.3 deg3.425 deg 781 km 28.5 deg2.1300km0 deg3836 km 17.3 deg3.45 deg2877 km 17.9 deg3.310 deg2193 km 19.9 deg2.925 deg1124 km 30.1 deg2.0400 km0 deg4401 km 19.8 de
25、g3.05 deg3422 km 20.4 deg2.910 deg2687 km 22.1 deg2.725 deg1412 km 31.4 deg1.9The higher the layer, the longer the hop distance for a given angle But the higher the layer, the lower the M-Factor (lower MUF) for a given angle PVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LARule of 3 and Rul
26、e of 5For the FFor the F2 2 region with region with low angleslow angles, the MUF is , the MUF is approximately 3 times the critical frequencyapproximately 3 times the critical frequency Ionosondes report the M-Factor for a 3000 km hopIonosondes report the M-Factor for a 3000 km hop M(3000)F2 or M(D
27、) where D = 3000 kmM(3000)F2 or M(D) where D = 3000 kmFor the E region with For the E region with low angleslow angles, the MUF is , the MUF is approximately 5 times the critical frequencyapproximately 5 times the critical frequency Close enough for sporadic E, tooClose enough for sporadic E, tooAll
28、ows you to estimate the MUF only knowing the critical frequencyPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LASunspots and Solar FluxDuring Cycle 23PVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAWhy Use Smoothed Solar Indices? Reason #1: Daily data (and even monthly mean data)
29、is spiky - Reason #1: Daily data (and even monthly mean data) is spiky - hard to tell whats happeninghard to tell whats happening Reason #2: The best correlation between what the Sun is doing and Reason #2: The best correlation between what the Sun is doing and what the ionosphere is doing is throug
30、h a smoothed solar index - what the ionosphere is doing is through a smoothed solar index - this is the basis on which the statistical model of the ionosphere for this is the basis on which the statistical model of the ionosphere for our propagation predictions was developedour propagation predictio
31、ns was developedPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAEarly CorrelationEquation from texts on the ionosphere: SF12 = 63.75 + .728 SSN12 + .00089 SSN122 (the “12” subscript denotes smoothed values)Side note - there is very little correlation between daily 10.7 cm solar flux and da
32、ily sunspot numberPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAMore DataSome more scatter about the trend line, but still pretty good.Some more scatter about the trend line, but still pretty good.PVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAInclude Cycle 23 In terms of smoo
33、thed sunspot number, second peak is a bit In terms of smoothed sunspot number, second peak is a bit lowerlower In terms of smoothed solar flux, second peak is definitely In terms of smoothed solar flux, second peak is definitely higherhigher We had much better 6m F2 propagation during the second pea
34、kWe had much better 6m F2 propagation during the second peakCycle 23 dataApril 2000Nov 2001PVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAWhy The Anomaly? Dr. Leif Dr. Leif SvalgaardSvalgaard (member of the Cycle 24 Prediction Panel) has several (member of the Cycle 24 Prediction Panel) h
35、as several opinionsopinions The sunspot counting procedure or observers have changed with resulting The sunspot counting procedure or observers have changed with resulting artificial changes of the sunspot number (as they have in the past)artificial changes of the sunspot number (as they have in the
36、 past) There are changes in the Suns corona or There are changes in the Suns corona or chromospherechromosphere accounting for accounting for additional 10.7 cm emissionadditional 10.7 cm emission Penn and Livingstons observations (Penn, M. J. and W. Livingston, Penn and Livingstons observations (Pe
37、nn, M. J. and W. Livingston, Temporal Temporal Changes in Sunspot Changes in Sunspot UmbralUmbral Magnetic Fields and Temperatures Magnetic Fields and Temperatures, , The The Astrophysical JournalAstrophysical Journal, 649, L45-L48, 2006 September 20) suggest that , 649, L45-L48, 2006 September 20)
38、suggest that sunspots have been getting warmer during the last decade, leading to a sunspots have been getting warmer during the last decade, leading to a decreased contrast with the surrounding photosphere and hence lessened decreased contrast with the surrounding photosphere and hence lessened vis
39、ibility, possibly resulting in an undercount of sunspotsvisibility, possibly resulting in an undercount of sunspots No definite answer (yet!)No definite answer (yet!) Visit http:/Visit http:/www.leif.orgwww.leif.org/research and select item 1020 for details/research and select item 1020 for details
40、Check out my Propagation columns in the forthcoming May 2011 and Check out my Propagation columns in the forthcoming May 2011 and June 2011 issues of June 2011 issues of WorldRadioWorldRadio Online for more on this Online for more on this http:/http:/ /WRO is free !WRO is free !PVRC Webinar Mar 9, 2
41、011 K9LAPVRC Webinar Mar 9, 2011 K9LAIonosphere-Ionosphere ModesPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAMulti-Hop Can Have Limits On the lower bands there may be too much absorption for multi-hop the On the lower bands there may be too much absorption for multi-hop the signal is to
42、o weaksignal is too weak On the higher bands the MUF may not be high enough to refract the ray On the higher bands the MUF may not be high enough to refract the ray back to Earth for multi-hop the ray goes out into spaceback to Earth for multi-hop the ray goes out into spaceionosphereEarthPVRC Webin
43、ar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAHigher MUF & Less AbsorptionAre there modes that could give a higher MUF and/or lesser absorption?Yes - there appear to be three of themChordal hopChordal hopDuctDuctPedersen RayPedersen Raychordal hopunaffected by the ionospherein between refraction p
44、ointsductconsecutive refractionsbetween E and F regions Pedersen Rayhigh angle ray, close to MUF,parallels the EarthPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAChordal HopExample TEP (trans-equatorial propagation)Example TEP (trans-equatorial propagation)K6QXY to ZL on 6mRay trace from
45、 Proplab Promonthly median results High density of electrons on either side of geomagnetic equatorHigh density of electrons on either side of geomagnetic equator Extremely long hop approximately twice a normal hopExtremely long hop approximately twice a normal hop Only two transits through the absor
46、bing regionOnly two transits through the absorbing region No ground reflectionsNo ground reflections Literature says MUF is approximately 1.5 times normal F2 hopLiterature says MUF is approximately 1.5 times normal F2 hoprefractionrefractionhelps MUF and absorptionarea of higher electron densityarea
47、 of higher electron densityPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LADuct Requires upper and lower boundary for successive refractionsRequires upper and lower boundary for successive refractions Need entry and exit criteria - small range of anglesNeed entry and exit criteria - small
48、range of angles No transits through the absorbing regionNo transits through the absorbing region No ground reflectionsNo ground reflections Low grazing angles with ionosphere higher MUFLow grazing angles with ionosphere higher MUF Believed to allow extremely long distance QSOs on 160mBelieved to all
49、ow extremely long distance QSOs on 160mhelps MUF and absorptionPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAPedersen Ray Not a lot in the literature on Not a lot in the literature on the Pedersen Raythe Pedersen Ray Comment from Comment from Ionospheric Ionospheric RadioRadio (Davies, 1
50、990) (Davies, 1990) Across the North Atlantic, Across the North Atlantic, occurrence tends to peak occurrence tends to peak near noon at the midpointnear noon at the midpoint One would surmise that the One would surmise that the ionosphere needs to be very ionosphere needs to be very stable for a ra
51、y to exactly stable for a ray to exactly parallel the Earth for long parallel the Earth for long distancesdistances Probably no help with MUF Probably no help with MUF biggest advantage appears to biggest advantage appears to be with lower absorption due be with lower absorption due to less transits
52、 of the to less transits of the absorbing region and no absorbing region and no ground reflection lossesground reflection losseshelps absorption 1 and 2 are “low-angle” paths1 and 2 are “low-angle” paths 3 is “medium-angle” path3 is “medium-angle” path 4 and 5 are “high-angle” 4 and 5 are “high-angl
53、e” Pedersen Ray pathsPedersen Ray paths 6 goes thru the ionosphere6 goes thru the ionospherePVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAA Detailed 20m Analysis K2MO (AA2AE at the time) to K2MO (AA2AE at the time) to ZS5BBO on July 5, 2003 at 1230 ZS5BBO on July 5, 2003 at 1230 UTC on 2
54、0m SSB via long pathUTC on 20m SSB via long path K2MO reported that ZS5BBOs K2MO reported that ZS5BBOs signal was around S7 ( -83 dBm)signal was around S7 ( -83 dBm)Long path from W2 starts off in daylight, goes into darkness, and ends in daylightShort path has high MUF but marginal signal strength
55、due to absorption Long path signal strength from ZS Long path signal strength from ZS predicted to be -125 dBmpredicted to be -125 dBm About 40 dB shy of S7About 40 dB shy of S7Short path 12,700 kmLong path 27,300 kmPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAThe Ionosphere Along the L
56、P Note the tilts in the Note the tilts in the ionosphere at dawn ionosphere at dawn (W2 end) and at (W2 end) and at dusk (ZS end)dusk (ZS end) Tilt can refract the Tilt can refract the ray so that it ray so that it encounters the encounters the ionosphere at more ionosphere at more of a grazing angl
57、e of a grazing angle (i.e., a higher MUF)(i.e., a higher MUF) Good entry/exit Good entry/exit criteria for ductcriteria for ductVK5PVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LARay Trace from W2 End Proplab Pro can only ray Proplab Pro can only ray trace out to 20,000 km (half trace out
58、to 20,000 km (half way around)way around) Do two ray tracesDo two ray traces One from W2 end (pictured)One from W2 end (pictured) One from ZS end (not pictured)One from ZS end (not pictured) Ray trace from ZS end Ray trace from ZS end shows similar ductingshows similar ducting Signal strength now Si
59、gnal strength now estimated to be -89 dBmestimated to be -89 dBm Close to observed -83 dBmClose to observed -83 dBmPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LAThe Big Picture My crude picture on the left My crude picture on the left shows chordal hops as the shows chordal hops as the i
60、onosphere-ionosphere modeionosphere-ionosphere mode Proplab Pro data indicates Proplab Pro data indicates the K2MO-to-ZS5BBO QSO the K2MO-to-ZS5BBO QSO was ductingwas ducting Easier to draw chordal hops!Easier to draw chordal hops! Youve probably seen a Youve probably seen a similar picture in the s
61、imilar picture in the propagation literature. propagation literature. Ionosphere-ionosphere modes are our friendsPVRC Webinar Mar 9, 2011 K9LAPVRC Webinar Mar 9, 2011 K9LASummaryI hope you learned somethingI hope you learned somethingThis This webinarwebinar will be on the PVRC web site will be on t
62、he PVRC web site http:/http:/www.pvrc.org/webinar/webinars.htmwww.pvrc.org/webinar/webinars.htm The slides will also be at http:/ slides will also be at http:/ Follow-up webinarswebinars: More Selected Topics in Propagation: More Selected Topics in Propagation Such as noise, 10m long path, effect of
63、 the Moon on HF propagation, Such as noise, 10m long path, effect of the Moon on HF propagation, trans-equatorial propagationtrans-equatorial propagationE-mail me if you have a specific topicE-mail me if you have a specific topic Also visit http:/ visit http:/ to Ken K4ZW and to the PVRCThanks to Ken K4ZW and to the PVRCAnd now . . . . . . . . . . . Q/AAnd now . . . . . . . . . . . Q/A
