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SSNe24 7-day plot

Note: This plot is updated hourly.

Track the status of the solar-cycle for the past 14 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 heavy dotted line indicates the highest value for both-hemisphere 24-hour SSNe so far in Cycle 25.

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: 20210514                          000000000011111111112222    
GMLAT  Station              Used  Rej   012345678901234567890123    
-----  -------------------  ---- ----  +|-----------------------+   
 49.8  EAREKSON               22   00  || XXXXXXXXXXXXXXXXXXXXXX| NH
 49.7  BOULDER                24   00  |XXXXXXXXXXXXXXXXXXXXXXXX| NH
 49.3  FAIRFORD               17   00  |XXXXXXX    XXX XXXXX XX | NH
 48.5  WALLOPS_IS             24   00  |XXXXXXXXXXXXXXXXXXXXXXXX| NH
 47.0  PRUHONICE              16   00  |XX XXX    XXXX  XXX XXXX| NH
 43.9  KHABAROVSK             11   00  || X  XXXX  XXXXXX       | NH
 42.3  EGLIN_AFB              22   00  |XXXXXXXXXXXXXXXX XX XXXX| NH
 42.0  POINT_ARGUELLO         19   00  |XXXXX   XXXXXXXXX X XXXX| NH
 40.6  WAKKANAI               20   00  |XXX XXXX XXXXX XX XXXXXX| NH
 36.8  SAN_VITO               19   00  |XXXXXXXXXXXX XX    XXXXX| NH
 33.7  GIBILMANNA             19   00  |XXXXXXXX XXX XXXXXX X X | NH
 31.8  NICOSIA                18   00  |XXXXXX    XX XXXXXXXXX X| NH
 31.3  KOKUBUNJI              11   00  ||XX    X  X XX  X  XX XX| NH
 28.9  PUERTO_RICO            23   00  |XXX XXXXXXXXXXXXXXXXXXXX| NH
 27.4  YAMAGAWA               14   00  |X   XX XXXX X X  X XXX X| NH
 24.3  LUALUALEI              24   00  |XXXXXXXXXXXXXXXXXXXXXXXX| NH
 23.1  OKINAWA                15   00  |X  X  XXXXXX  X XX  XXXX| NH
-12.7  SAO_LUIS               16   01  |XX       XXXXXXXXXXXXXX-|   
-14.3  FORTALEZA              15   02  ||  XXX   XXXXXXXXXXXX-- |   
-20.0  TUCUMAN                20   00  ||X  XXXXXXXXXXXXXXXXXXX | SH
-22.2  ASCENSION              17   01  |XX     XXXXXXXXXX-XXXXX | SH
-23.0  CACHOEIRA_PAULISTA     18   00  ||   XXXXXXXXXXXXXXXXX  X| SH
-24.5  DARWIN                 14   00  |X XX XXXXXXXX       X XX| SH
-24.5  NIUE                   20   00  ||XXXXXXX XXXXXX  XXXXXXX| SH
-29.8  BAHIA_BLANCA           22   00  |XXX XXXXXXXXXXXXXXXXXXX | SH
-30.8  TOWNSVILLE             23   00  |XXXXXXXXXXXXXXXXXXX XXXX| SH
-34.2  LEARMONTH              16   06  ||XXXXXXXXXXXXXXXX------ | SH
-37.5  NORFOLK_IS             23   00  |XXX XXXXXXXXXXXXXXXXXXXX| SH
-37.6  BRISBANE               21   00  |XXXXXXXXXX XXXXX XXXXX X| SH
-45.0  PERTH                  13   08  |XXX XXXXXXXXX---- -- --X| SH
-46.5  CANBERRA               19   00  ||X XX  XXXXXXXXXXX XXXXX| SH
-------------------  -----  ---- ----  +|-----------------------+   
NH  :   # Expected / # Received / Percent:  624 /  318 /  51.0
ALL :   # Expected / # Received / Percent: 1248 /  593 /  47.5
SH  :   # Expected / # Received / Percent:  384 /  241 /  62.8
 

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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