NOTE TO USERS : NCEI Termination of Data.

NWRA Effective Smoothed Sunspot Numbers

:Product: NWRA 24h Effective SSN Analysis
:Issued: 2024-05-13 01:41 UT
#  Prepared by NorthWest Research Associates, Inc. 
#  Uses foF2 data from NOAA/NCEI.
#
#Hemisphere YYYYMMDD HH   SSNe     RMS    RMS%    #  Status
#---------- -------- --  ------  ------  ------  --- ------
 Global     20240513 01   71.99    2.12   40.73  303   GRN
#---------- -------- --  ------  ------  ------  --- ------
# Status: Green
# Hours to last foF2 observation: 0
#
Listings of past 5 hours:
Global SSNe
YYYYMMDD HH   SSNe     RMS    RMS%    #
-------- --  ------  ------  ------  ---
20240512 21   60.76    2.13   43.57  289
20240512 22   63.72    2.17   42.69  295
20240512 23   66.05    2.16   42.18  297
20240513 00   69.45    2.15   40.95  300
20240513 01   71.99    2.12   40.73  303
-------- --  ------  ------  ------  ---

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 two different set of observed foF2: (1) all observations equatorward of 50 degrees geomagnetic latitude over the past 24 hours (SSNe24), and (2) all observations equatorward of 50 degrees geomagnetic latitude over the past 6 hours (SSNe06).

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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