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

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  • 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 1 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 2 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 3 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 4 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 5 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 6 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 7 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 8 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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