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NOTE: Product changes due to switch from SWPC to NCEI for data (UPDATED 26 March 2020)

SSNe24 7-day plot

Note: This plot is updated hourly.

Track the status of the solar-cycle for the past 12 months or for Cycles 23-25.

If you are looking for the observed sunspot number derived from optical observations of the sun, you've been miss-routed.
This link provides a comparison of the effective SSN shown on this page to the observed solar sunspot number.


These plots provide a look at the global behavior of the ionospheric F2 layer over the past week as measured by the NWRA effective sunspot number (SSNe) calculated from current observations. The upper panel shows the SSNe variation, the third panel provides a goodness-of-fit metric (described below), and the lower panel gives the total number of foF2 observations in each SSNe calculation. In all three panels the two black curves use data from observatories between -50 and +50 degrees geomagnetic latitude (heavy curve uses data collected from the previous 24 hours; light curve the previous 6 hours). The heavy green and red curves use data from observatories between -50 and -15, and +15 and +50 degrees geomagnetic latitude, respectively, collected during the previous 24 hours. (Note that the quasi- diurnal variation in the 6 hour SSNe values is primarily due to unequal longitude spacing of the foF2 stations from which the SSNe are being calculated.)

The second panel shows the provisional (quicklook) Kp index from GFZ Potsdam. This is provided to assess the impact of geomagnetic activity on SSNe.

Also shown on the upper panel is the long-term predicted smoothed sunspot number as provided by the NOAA Space Weather Prediction Center. The heavy dash line is the expected value from the prediction, and the two light dashed lines are the upper- and lower-bounds on the expected value.

The goodness-of-fit metric shown in the middle panel is the RMS percent difference between the foF2 observations used in the SSNe calculations and the model foF2 values generated using the SSNe in the URSI-88 foF2 model. It generally runs around 15%, with the largest departures occurring during major geomagnetic disturbances

The following table summarizes the observations used in calculating the most recent SSNe value. The X entry for a particular station/time indicates there was an foF2 value available and it was used in the SSNe calculation. A - entry indicates that an foF2 value was available, but it was excluded from the SSNe calculation (it was identified as an outlier point). The bar (|) symbol along the time axis of the table indicates the latest-data time (i.e., data to the right of this column are from the previous day). The SH and NH tags on the far right of each line indicates which stations were included in the southern- and northern-hemisphere SSNe calculations, respectively.

Date: 20200327                          000000000011111111112222    
GMLAT  Station              Used  Rej   012345678901234567890123    
-----  -------------------  ---- ----  +-----------------------|+   
 49.8  EAREKSON               24   00  |XXXXXXXXXXXXXXXXXXXXXXXX| NH
 49.7  BOULDER                24   00  |XXXXXXXXXXXXXXXXXXXXXXXX| NH
 49.3  FAIRFORD               24   00  |XXXXXXXXXXXXXXXXXXXXXXXX| NH
 49.2  CHILTON                24   00  |XXXXXXXXXXXXXXXXXXXXXXXX| NH
 47.2  DOURBES                24   00  |XXXXXXXXXXXXXXXXXXXXXXXX| NH
 47.0  PRUHONICE              24   00  |XXXXXXXXXXXXXXXXXXXXXXXX| NH
 42.3  EGLIN_AFB              18   00  |XXXXXXXXX   XXX  XXX XXX| NH
 42.0  POINT_ARGUELLO         24   00  |XXXXXXXXXXXXXXXXXXXXXXXX| NH
 41.5  AUSTIN                 11   07  |XX---  --    --XXXXXXXXX| NH
 40.6  WAKKANAI               18   00  |XXXXXXXXXXXX   X X  XXXX| NH
 36.8  SAN_VITO               23   00  |XXXXXX XXXXXXXXXXXXXXXXX| NH
 33.1  I-CHEON                06   00  |XXXXX  X               || NH
 31.3  KOKUBUNJI              18   00  |XXXXXXXXXXXXX X     XXXX| NH
 29.7  JEJU                   08   00  |     X    X  X  XXXX X || NH
 28.9  PUERTO_RICO            20   00  |XX XXXXX   XXXXXXXXXXXXX| NH
 27.4  YAMAGAWA               22   00  |XXXXXXXXXXXXXXXX XXX XXX| NH
 24.3  LUALUALEI              23   00  |XXXXXXXX XXXXXXXXXXXXXXX| NH
 23.1  OKINAWA                22   00  |XXXXXXXXXXX XXXXXXXX XXX| NH
 13.7  GUAM                   24   00  |XXXXXXXXXXXXXXXXXXXXXXXX|   
-12.2  JICAMARCA              13   02  |X --X       XXXXX XXXXXX|   
-12.7  SAO_LUIS               19   01  |X-XXXX   XXXXXXXX XXXXXX|   
-14.3  FORTALEZA              19   02  |X--XXX   XXXXXXXXXXXXXXX|   
-20.0  TUCUMAN                16   00  |X    X X   XXXXXXXXXXXXX| SH
-22.2  ASCENSION              14   01  |XX     XXXX XXXXXXX - X|| SH
-23.0  CACHOEIRA_PAULISTA     14   03  |    X  X XXXXXXXXXXX---X| SH
-24.5  DARWIN                 22   00  |XXXXXXXXXXXXXXXXX XXXX X| SH
-24.5  NIUE                   20   00  |X  XXXXX  XXXXXXXXXXXXXX| SH
-25.0  COCOS                  12   00  |XXXXXXXXXX  XX         || SH
-29.8  BAHIA_BLANCA           20   00  |  XXX XXXXX XXXXXXXXXXXX| SH
-34.2  LEARMONTH              24   00  |XXXXXXXXXXXXXXXXXXXXXXXX| SH
-37.5  NORFOLK_IS             24   00  |XXXXXXXXXXXXXXXXXXXXXXXX| SH
-37.6  BRISBANE               21   00  |XXXXXX X XXXXXXXXXXX XXX| SH
-43.1  GRAHAMSTOWN            24   00  |XXXXXXXXXXXXXXXXXXXXXXXX| SH
-45.0  CAMDEN                 24   00  |XXXXXXXXXXXXXXXXXXXXXXXX| SH
-45.0  PERTH                  24   00  |XXXXXXXXXXXXXXXXXXXXXXXX| SH
-46.5  CANBERRA               23   00  |XXXXXXXXXXXXXXXXXXX XXXX| SH
-------------------  -----  ---- ----  +-----------------------|+   
NH  :   # Expected / # Received / Percent:  624 / 364 /  58.3
ALL :   # Expected / # Received / Percent: 1104 / 730 /  66.1
SH  :   # Expected / # Received / Percent:  360 / 286 /  79.4
 

If you would like to get a feel for how effective these effective-SSN indices are, foF2 plots comparing the observations with model foF2 values calculated using the NWRA SSNe and the SWS T indexes are available. There is a one-day delay between the latest SSNe values available and these plots to permit more data to arrive at the NOAA NCEI for comparison.

Boulder foF2 Plot Daily foF2 Comparison Plots


The foF2 data used in these calculations were obtained from the NOAA NCEI.

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