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Re: [dxatlas] 90-day SSN data for HamCAP

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  • Pete Smith
    I think the thing that is confusing Bill (and me, for that matter) is the large divergence between the various sunspot numbers available to plug into Ham Cap.
    Message 1 of 17 , Apr 9 4:00 AM
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      I think the thing that is confusing Bill (and me, for that matter) is the
      large divergence between the various sunspot numbers available to plug into
      Ham Cap. For example, for April 2005:

      Ham Cap's built-in number (old NOAA predicted): 30
      Current NOAA predicted smoothed SSN: 28.5 (pretty close)
      IonoProbe's computed 90-day smoothed SSN: 47 (!)

      The difference in the outcome is meaningful -- for example, with the SSN at
      30, for my short path to 3B8, 15 M opens only briefly, although there is a
      long period when the MUF is predicted to be right below 15. With the SSN
      set at 47, 15M is predicted to be open for essentially the same fairly long
      period, and a second night-time 20M opening is also predicted.

      Like Alex, I think I prefer IonoProbe's number, not because of the outcome
      but because it seems to reflect what is more currently happening than a
      projection from 6 months ago. On the other hand, I understand that VOACAP
      is really built around the 13-month number, so during a period when the
      90-day number diverges substantially upward from the 13-month average, the
      predictions may be unduly rosy.

      While we're on the subject, a question I have wondered about -- why do Ham
      Cap's charts not have a graduated hour scale on the X axis? Have I missed
      an option to turn them on?

      73, Pete N4ZR


      At 05:07 PM 4/8/2005, Alex, VE3NEA wrote:


      >Since HamCap is just a front end to VOACAP, you should use the same
      >parameters with this program as you would use with VOACAP itself.
      >
      >VOACAP expects the 13-month average SSN which can be found, in particular,
      >at
      >ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_NUMBERS/SMOOTHED/
      >
      >Unfortunately, this index if published with a 6-month lag due to averaging.
      >Unless you want to see what the propagation was half a year ago, you should
      >use some other SSN index that is close enough to the 13-month average but is
      >available for the current month.
      >
      >One possible solution to this problem is to use the predicted smoothed SSN
      >that NOAA publishes at
      >ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_NUMBERS/SUNSPOT.LST
      >Keep in mind, however, that these predictions are not always accurate.
      >HamCap has a list of such predictions, published at the time of program
      >release, in the file called SSN.dat. These data are used to populate the SSN
      >box in the program when the month changes. You can open the file in Notepad
      >and compare its content to the current NOAA predictions.
      >
      >Another solution that I like more is to use the 90-day SSN that IonoProbe
      >calculates by averaging the daily SSN over the last 3 months (you may have
      >to use the Download Old Data command in the program to ensure that enough
      >daily data are available).
      >
      >73 Alex VE3NEA
      >
      >
      >
      >
      > >
      > > Good question -- I see that IonoProbe displays a value for this parameter
      > > -- currently 47, not 20. I, too, could not find a source for the 90-day I
      > > average. Iam not sure if it is downloaded or automatically calculated
      >from
      > > the daily numbers provided in one or another of the standard reports. I
      > > did note, though, that if you have IonoProbe, it automatically links with
      > > Hamcap to provide the necessary updated number.
      > >
      > > 73, Pete N4ZR
      > >
      > > At 09:26 AM 4/8/2005, bill_w4zv wrote:
      > >
      > >
      > >
      > > >Alex or anyone:
      > > >
      > > >HamCAP apparently wants the 90-day smoothed sunspot number in the
      > > >Parameters screen. I can't seem to find that on any of the NOAA
      > > >databases. Is it the same as the projected number on the following
      > > >graph for the current month? It's not clear to me what period they
      > > >are smoothing over for this graph.
      > > >
      > > >http://www.sel.noaa.gov/ftpdir/weekly/sunspot.gif
      > > >
      > > >If I am interpolating correctly, the current smoothed SSN is about 20.
      > > > Is that the correct number to input to HamCAP?
      > > >
      > > >73, Bill W4ZV
      >
      >
      >
      >
      >Yahoo! Groups Links
      >
      >
      >
      >
    • bill_w4zv
      ... is the ... plug into ... Yet the average montthly sunspots for the past 3 months are: 2005 01 31.3 2005 02 29.1 2005 03 24.8 Average = 28.4, which is
      Message 2 of 17 , Apr 9 5:29 AM
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        --- In dxatlas_group@yahoogroups.com, Pete Smith <n4zr@c...> wrote:
        > I think the thing that is confusing Bill (and me, for that matter)
        is the
        > large divergence between the various sunspot numbers available to
        plug into
        > Ham Cap. For example, for April 2005:
        >
        > Ham Cap's built-in number (old NOAA predicted): 30
        > Current NOAA predicted smoothed SSN: 28.5 (pretty close)
        > IonoProbe's computed 90-day smoothed SSN: 47 (!)

        Yet the average montthly sunspots for the past 3 months are:

        2005 01 31.3
        2005 02 29.1
        2005 03 24.8

        Average = 28.4, which is very close to the built-in 30 and current
        NOAA predicted 28.5.

        ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_NUMBERS/MONTHLY.PLT

        How can IonoProbe's computed 90-day SSN possibly be 47? This is
        different by nearly a factor of two!

        73, Bill
      • bill_w4zv
        ... Could IonoProbe s calculation be off by one year? I notice 47 is very close to the SSN numbers for this time last year: 2004 52.0 49.3 47.1 45.6
        Message 3 of 17 , Apr 9 5:40 AM
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          I wrote:

          > How can IonoProbe's computed 90-day SSN possibly be 47? This is
          > different by nearly a factor of two!

          Could IonoProbe's calculation be off by one year? I notice 47 is very
          close to the SSN numbers for this time last year:

          2004 52.0 49.3 47.1 45.6 43.9 41.7 40.2 39.2 37.5

          ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_NUMBERS/SMOOTHED

          And the average of 49.3, 47.1, and 45.6 is 47.3. Maybe the logic of
          the calculation has an error somewhere in its data collection.

          73, Bill (...using 29 for now)
        • Pete Smith
          Bill, aren t those numbers predicted from 6 months ago? I looked at the graphed SSNs for the last three months from IonoProbe and they seem much more
          Message 4 of 17 , Apr 9 6:10 AM
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            Bill, aren't those numbers predicted from 6 months ago? I looked at the
            graphed SSNs for the last three months from IonoProbe and they seem much
            more consistent with the 47 average.

            73, Pete

            At 08:29 AM 4/9/2005, bill_w4zv wrote:



            >--- In dxatlas_group@yahoogroups.com, Pete Smith <n4zr@c...> wrote:
            > > I think the thing that is confusing Bill (and me, for that matter)
            >is the
            > > large divergence between the various sunspot numbers available to
            >plug into
            > > Ham Cap. For example, for April 2005:
            > >
            > > Ham Cap's built-in number (old NOAA predicted): 30
            > > Current NOAA predicted smoothed SSN: 28.5 (pretty close)
            > > IonoProbe's computed 90-day smoothed SSN: 47 (!)
            >
            >Yet the average montthly sunspots for the past 3 months are:
            >
            >2005 01 31.3
            >2005 02 29.1
            >2005 03 24.8
            >
            >Average = 28.4, which is very close to the built-in 30 and current
            >NOAA predicted 28.5.
            >
            >ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_NUMBERS/MONTHLY.PLT
            >
            >How can IonoProbe's computed 90-day SSN possibly be 47? This is
            >different by nearly a factor of two!
            >
            >73, Bill
            >
            >
            >
            >
            >
            >
            >Yahoo! Groups Links
            >
            >
            >
            >
          • bill_w4zv
            ... Definitely so. The current 90 day average (1 Jan 05 - 31 Mar 05) is 28.4 using this data:
            Message 5 of 17 , Apr 9 6:12 AM
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              I wrote:

              > Maybe the logic of
              > the calculation has an error somewhere in its data collection.

              Definitely so. The current 90 day average (1 Jan 05 - 31 Mar 05) is
              28.4 using this data:

              ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_NUMBERS/RIDAILY.PLT

              I don't have IonoProbe, but it must have a problem if the 47 number
              Pete quoted for the IonoProbe calculation is correct. Anyhow, now I
              know what to use and will probably just go with the NOAA forecast
              which seems to be fairly accurate at this stage of the cycle.

              73, Bill
            • Alex, VE3NEA
              ... I am not sure how monthly values presented on that page are calculated. IonoProbe just averages the last 90 daily values from
              Message 6 of 17 , Apr 9 9:40 AM
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                > Yet the average montthly sunspots for the past 3 months are:
                > 2005 01 31.3
                > 2005 02 29.1
                > 2005 03 24.8
                > Average = 28.4, which is very close to the built-in 30 and current
                > NOAA predicted 28.5.
                > ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_NUMBERS/MONTHLY.PLT
                > How can IonoProbe's computed 90-day SSN possibly be 47? This is
                > different by nearly a factor of two!

                I am not sure how monthly values presented on that page are calculated.
                IonoProbe just averages the last 90 daily values from
                http://www.sec.noaa.gov/ftpdir/latest/DSD.txt and
                http://www.sec.noaa.gov/ftpdir/indices/old_indices/




                > Could IonoProbe's calculation be off by one year? I notice 47 is very
                > close to the SSN numbers for this time last year:
                > 2004 52.0 49.3 47.1 45.6 43.9 41.7 40.2 39.2 37.5
                > ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_NUMBERS/SMOOTHED
                > And the average of 49.3, 47.1, and 45.6 is 47.3. Maybe the logic of
                > the calculation has an error somewhere in its data collection.

                IonoProbe does not have access to the data from the last year.


                > Definitely so. The current 90 day average (1 Jan 05 - 31 Mar 05) is
                > 28.4 using this data:
                > ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_NUMBERS/RIDAILY.PLT

                These are the RI indices, not daily SSN values.



                > Anyhow, now I
                > know what to use and will probably just go with the NOAA forecast
                > which seems to be fairly accurate at this stage of the cycle.

                You may want to enter the latest NOAA forecasts in the SSN.dat file using
                Notepad, then HamCap will use these data automatically.


                73 Alex VE3NEA
              • Bob Lafont
                Has anyone upgraded DX Atlas from 1.x to 2.x ? And if you have how did you go about getting the upgrade? 73-Bob WA2MNO [Non-text portions of this message have
                Message 7 of 17 , Apr 9 9:47 AM
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                  Has anyone upgraded DX Atlas from 1.x to 2.x ?

                  And if you have how did you go about getting the upgrade?



                  73-Bob
                  WA2MNO






                  [Non-text portions of this message have been removed]
                • Alex, VE3NEA
                  ... HamCap is an interactive application. When you move the mouse cursor over the chart, the time and all other parameters of the point under the cursor are
                  Message 8 of 17 , Apr 9 9:56 AM
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                    > While we're on the subject, a question I have wondered about -- why do Ham
                    > Cap's charts not have a graduated hour scale on the X axis? Have I missed
                    > an option to turn them on?

                    HamCap is an interactive application. When you move the mouse cursor over
                    the chart, the time and all other parameters of the point under the cursor
                    are displayed on the status bar.

                    I tried to make the HamCap window as small as possible so that it could be
                    used during contesting and DXing when screen space is a valuable resource,
                    so I removed all unnecessary elements form the user interface, including the
                    time scale on the chart.


                    73 Alex VE3NEA
                  • Alex, VE3NEA
                    A while ago I did some comparisons of median SNR predictions from VOACAP to the observations of NCSXF beacons. Ingemar SM5AJV developed a program that measures
                    Message 9 of 17 , Apr 9 10:10 AM
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                      A while ago I did some comparisons of median SNR predictions from VOACAP to
                      the observations of NCSXF beacons. Ingemar SM5AJV developed a program that
                      measures the SNR of beacon signals using a sound card and an FFT
                      transformation. A correlator is used to compare the received waveform to
                      that of the beacon's callsign, to make sure that the signal actually comes
                      from the beacon. Ingemar was kind enough to send me his logs for June 2004,
                      these logs cover about 24% of the month.

                      I developed a viewer utility for the logs that converts the observed SNR
                      values
                      into dB-Hz, calculates medians, and plots both predicted and observed median
                      values along with the observation points for the selected beacon and band.
                      The program lacks a sophisticated user interface, which I may develop in the
                      future if there is sufficient interest. A few screenshots of typical plots
                      are here: http://www.dxatlas.com/Private/SnrPlot.zip .

                      For those who want to play with the viewer, I uploaded it to
                      http://www.dxatlas.com/Private/VoaAnal.zip .
                      The zip file also includes the observation data, with permission
                      from Ingemar. Please preserve the directory structure when unzipping.

                      Though this is just the first alpha version of the program and thus it may
                      contain errors, the plots it produces are very interesting. The shape of the
                      VOACAP prediction chart is very close to that of the observation chart,
                      though the absolute values are way off. On average, VOACAP underestimates
                      the SNR by 20+ dB.

                      Also, these charts explain why the median SNR is a bad indicator of
                      propagation conditions. The median value makes sense only for unimodal
                      distributions, while the distribution of SNR is bi-modal at best (that is,
                      has two or more peaks). One peak is formed by the observations that where
                      performed when the path was open with a good propagation mode, and one or
                      more peaks come from the days when only very lossy modes were available or
                      the path was closed.


                      73 Alex VE3NEA
                    • Pete Smith
                      OK - thanks! Makes sense. 73, Pete
                      Message 10 of 17 , Apr 9 11:27 AM
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                        OK - thanks! Makes sense.

                        73, Pete

                        At 12:56 PM 4/9/2005, Alex, VE3NEA wrote:



                        > > While we're on the subject, a question I have wondered about -- why do Ham
                        > > Cap's charts not have a graduated hour scale on the X axis? Have I missed
                        > > an option to turn them on?
                        >
                        >HamCap is an interactive application. When you move the mouse cursor over
                        >the chart, the time and all other parameters of the point under the cursor
                        >are displayed on the status bar.
                        >
                        >I tried to make the HamCap window as small as possible so that it could be
                        >used during contesting and DXing when screen space is a valuable resource,
                        >so I removed all unnecessary elements form the user interface, including the
                        >time scale on the chart.
                        >
                        >
                        >73 Alex VE3NEA
                        >
                        >
                        >
                        >
                        >
                        >
                        >Yahoo! Groups Links
                        >
                        >
                        >
                        >
                      • Pete Smith
                        [With apologies to readers of the VOACAP list, who are joining this in mid-thread, I feel that Bill and I are floundering fairly far out of our depth in this
                        Message 11 of 17 , Apr 9 11:32 AM
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                          [With apologies to readers of the VOACAP list, who are joining this in
                          mid-thread, I feel that Bill and I are floundering fairly far out of our
                          depth in this discussion that began on the dxatlas list. The question
                          began as what SSN to use in Ham Cap, a simplified front end for
                          VOACAP. HamCAP comes with a table of predicted international SSNs, but can
                          also link with IonoProbe, which downloads daily SSNs from the SEC. VE3NEA,
                          the author of Ham Cap, prefers the SEC numbers, but the variance from the
                          international SSns is considerable, with the SEC number typically running
                          much higher. Any advice appreciated!]

                          Bill, there's some apples and oranges, or something going on
                          here. IonoProbe gets its numbers from the Joint USAF/NOAA Solar and
                          Geophysical Activity Summary. Here's a sample:

                          "SGAS Number 099 Issued at 0245Z on 09 Apr 2005
                          This report is compiled from data received at SWO on 08 Apr
                          A. Energetic Events
                          Begin Max End Rgn Loc Xray Op 245MHz 10cm Sweep
                          None
                          B. Proton Events: None
                          C. Geomagnetic Activity Summary: The geomagnetic field was quiet.
                          D. Stratwarm: Not Available
                          E. Daily Indices: (real-time preliminary/estimated values)
                          10 cm 088 SSN 056 Afr/Ap 005/004 ...."

                          Ionoprobe's retrospective record of these reports shows March 12 (chosen
                          randomly) with a SSN of 67, versus 42 on the table you cite. March 18 is
                          37 versus 25, and so on.

                          I have no idea what the explanation is, though I do note that there is
                          another table, ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_NUMBERS/2005
                          , which gives the numbers just for this year to date and states that
                          "Values are preliminary after Dec 2004."

                          There is an interesting explanation of how various sunspot numbers are
                          calculated in
                          ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_NUMBERS/sunspot.predict. It
                          seems clear from this explanation that the international sunspot number is
                          a highly-massaged, worldwide average number that does not become final for
                          some months after the date of observation. By contrast, the number cited
                          in the SGAS is the SEC's every-six-hour figure, and must be based strictly
                          on its own observations. An interesting graph at
                          http://www.nwra-az.com/spawx/comp.html speaks to this. To quote from the
                          caption:

                          " This plot illustrates the differences between the "real" sunspot number
                          (SSN), which is calculated from optical observations of the sun, a sunspot
                          number derived from the 10.7cm solar radio flux (SSNf), and a sunspot
                          number derived from fitting an ionospheric model to ionospheric
                          measurements. All of these indices are used as inputs to models of the
                          ionosphere for use in communications-performance predictions - this plot
                          shows that they don't always agree as to what the SSN should be in that
                          particular context.

                          Note: The F10.7-derived SSN (SSNf) is calculated from the 10.7cm solar
                          radio flux (the Penticton Radio Observatory noon value) using the following
                          relationship:

                          F10.7 = 63.74 + 0.727*SSNf + 0.000895*SSNf**2

                          So, where does this leave us? Where it left me, frankly, is wondering why
                          we use sunspot numbers at all, rather than solar flux and A/K indices, or
                          at least the SSNf, which would be closer to the values Bill cited than to
                          the current high value of optically-observed SSN. On the other hand, Alex
                          argues that results from using the lower SSNs seem to run consistently low
                          in terms of predicted vs. observed S/R ratio.

                          It would be interesting to pass this discussion over to the VOACAP list and
                          see what the gurus there, particularly including Greg Hand and George Lane,
                          think of it. In fact, I have done that, and it will be interesting to see
                          what comes of it.

                          73, Pete N4ZR



                          At 09:12 AM 4/9/2005, bill_w4zv wrote:



                          >I wrote:
                          >
                          > > Maybe the logic of
                          > > the calculation has an error somewhere in its data collection.
                          >
                          >Definitely so. The current 90 day average (1 Jan 05 - 31 Mar 05) is
                          >28.4 using this data:
                          >
                          >ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_NUMBERS/RIDAILY.PLT
                          >
                          >I don't have IonoProbe, but it must have a problem if the 47 number
                          >Pete quoted for the IonoProbe calculation is correct. Anyhow, now I
                          >know what to use and will probably just go with the NOAA forecast
                          >which seems to be fairly accurate at this stage of the cycle.
                          >
                          >73, Bill
                          >
                          >
                          >
                          >
                          >
                          >
                          >Yahoo! Groups Links
                          >
                          >
                          >
                          >
                        • bill_w4zv
                          ... wondering why ... I agree. Seems like measured solar flux, which supposedly shows the actual effect of sunspots on the ionosphere, would be better. After
                          Message 12 of 17 , Apr 10 4:40 AM
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                            --- In dxatlas_group@yahoogroups.com, Pete Smith <n4zr@c...> wrote:

                            >
                            > So, where does this leave us? Where it left me, frankly, is
                            wondering why
                            > we use sunspot numbers at all, rather than solar flux and A/K indices,

                            I agree. Seems like measured solar flux, which supposedly shows the
                            actual effect of sunspots on the ionosphere, would be better. After
                            all, when there is a large CME, we often can see little effect on the
                            ionosphere depending on how it's directed toward Earth, which way Bz
                            points, etc. Of course if VOACAP was originally based on SSN's, then
                            maybe they should be the input. Hopefully Greg Hand will respond, and
                            please post anything of interest here since I am not on that list. No
                            model is any better than its input..."Garbage In Garbage Out" as
                            someone said.

                            73, Bill
                          • bill_w4zv
                            I wrote: The current 90 day average (1 Jan 05 - 31 Mar 05) is 28.4 using this data: ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_NUMBERS/RIDAILY.PLT VE3NEA
                            Message 13 of 17 , Apr 10 12:50 PM
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                              I wrote: The current 90 day average (1 Jan 05 - 31 Mar 05) is
                              28.4 using this data:
                              ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_NUMBERS/RIDAILY.PLT

                              VE3NEA wrote: These are the RI indices, not daily SSN values.

                              Alex, the NOAA site below calls these "Provisional International
                              Sunspot Numbers, so what do you mean they are not daily SSN numbers?
                              See especially their comments preceded by ***** below:
                              ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_NUMBERS/sunspot.predict

                              >The provisional daily Zurich relative sunspot numbers, Rz, were based
                              upon
                              observations made at Zurich and its two branch stations in Arosa and
                              Locarno
                              and communicated by M. Waldmeier of the Swiss Federal Observatory.
                              Beginning
                              January 1, 1981, the Zurich relative sunspot number program is
                              replaced by
                              the "Sunspot Index Data Center" (c/o Dr. P. Cugnon, 3 av. Circulaire,
                              B-1180
                              Bruxelles, Belgium).


                              ***** The determination of the provisional International Sunspot
                              Numbers Ri results from a statistical treatment of the data
                              originating from more than twenty-five observing stations. These
                              stations constitute an international network, with the Locarno
                              (Switzerland) station as the reference station, to guarantee
                              continuity with the past Zurich series of Rz.*****

                              >The definitive International Sunspot Numbers Ri are evaluated by a
                              similar method based on a network of observing stations selected for
                              their
                              high number of observations, their continuity during the whole year
                              and an
                              existing series of observations during the last years. Also taken into
                              account is the stability of the K monthly factors with reference to the
                              Locarno station.

                              *****These relative sunspot numbers are now designated Ri
                              (International) instead of Rz (Zurich).*****

                              It seems to me Ri is exactly what should be used, but am really
                              waiting to see what Greg Hand, etc. of VOACAP have to say.

                              73, Bill
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