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:Product: NWRA 24h Effective SSN Analysis :Issued: 2023-09-22 20:41 UT # Prepared by NorthWest Research Associates, Inc. # Uses foF2 data from NOAA/NCEI. # #Hemisphere YYYYMMDD HH SSNe RMS RMS% # Status #---------- -------- -- ------ ------ ------ --- ------ Global 20230922 20 113.08 1.22 17.13 560 GRN Northern 20230922 20 115.29 1.01 13.71 264 GRN Southern 20230922 20 111.47 1.37 19.59 270 GRN #---------- -------- -- ------ ------ ------ --- ------ # Status: Green # Hours to last foF2 observation: 0 # Listings of past 5 hours: Global SSNe YYYYMMDD HH SSNe RMS RMS% # -------- -- ------ ------ ------ --- 20230922 16 113.09 1.19 17.29 561 20230922 17 112.88 1.20 16.98 561 20230922 18 112.83 1.21 17.05 560 20230922 19 112.77 1.22 17.15 560 20230922 20 113.08 1.22 17.13 560 -------- -- ------ ------ ------ --- Northern Hemisphere SSNe YYYYMMDD HH SSNe RMS RMS% # -------- -- ------ ------ ------ --- 20230922 16 115.67 1.00 14.53 263 20230922 17 114.55 1.02 13.55 264 20230922 18 114.42 1.02 13.57 264 20230922 19 114.56 1.03 13.92 264 20230922 20 115.29 1.01 13.71 264 -------- -- ------ ------ ------ --- Southern Hemisphere SSNe YYYYMMDD HH SSNe RMS RMS% # -------- -- ------ ------ ------ --- 20230922 16 111.20 1.32 19.25 271 20230922 17 111.56 1.33 19.40 271 20230922 18 111.62 1.35 19.53 270 20230922 19 111.45 1.36 19.49 270 20230922 20 111.47 1.37 19.59 270 -------- -- ------ ------ ------ ---Updated hourly at 40 minutes past the hour The SSNe index presented on the NWRA website is calculated using the URSI coefficient-based model for foF2 commonly referred to as the URSI-88 model (Rush et al., 1989). The foF2 data used are provided from a global network of ionospheric sounders currently collected at the National Centers for Environmental Information (NCEI). An SSNe index is generated once per hour for four different set of observed foF2: (1) all observations equatorward of 50 degrees geomagnetic latitude over the past 24 hours (SSNe24), (2) all observations equatorward of 50 degrees geomagnetic latitude over the past 6 hours (SSNe06), (3) all observations between +15 and +50 degrees geomagnetic latitude (NH SSNe24) over the past 24 hours, and (4) all observations between -15 and -55 degrees geomagnetic latitude (SH SSNe24) over the past 24 hours. A more detailed description of the algorithms used and a review of the efficacy of using SSNe can be found in Secan and Wilkinson (1997). NOTE: The international solar community has recalibrated and rescaled the sunspot number and refer to the new scaling as the V2.0 sunspot series. The foF2 model the SSNe estimate is calculated from was based on the V1.0 sunspot number series. Thus all SSNe values are inherently tied to the V1.0 scaling. If the software you plan to use SSNe with explicitly states that the input sunspot number must be consistent with the V2.0 sunspot series you should divide the SSNe by 0.7 to obtain the corresponding V2.0 value. Rush, C., M. Fox, D. Bilitza, K. Davies, L. McNamara, F. Stewart, and M. PoKempner, Ionospheric Mapping: An Update of foF2 Coefficients, Telecommun. J., 56(179), 1989. Secan, J.A. and P.J. Wilkinson, Statistical studies of an effective sunspot number, Radio Science, 32, 1717-1724, 1997. |
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