LOGO

Main Pages: [ SpaWx Indices Home | NWRA Home Page | ]
Graphics: [ X-ray | F10 | Ap | F10/Ap Forecasts | SSNe | SSN Comparison | 24hr SSNe | Kp+GOES+DSCOVR | Qe+GOES+DSCOVR ]
Listings/Reports: [ Indices Table | Events | RSGA | Discussion | SGAS | SRS | Predict | NWRA SSNe ]

NWRA Effective Smoothed Sunspot Numbers

:Product: NWRA 24h Effective SSN Analysis
:Issued: 2023-06-03 09:41 UT
#  Prepared by NorthWest Research Associates, Inc. 
#  Uses foF2 data from NOAA/NCEI.
#
#Hemisphere YYYYMMDD HH   SSNe     RMS    RMS%    #  Status
#---------- -------- --  ------  ------  ------  --- ------
 Global     20230603 09   99.09    1.29   28.51  599   GRN
 Northern   20230603 09  108.71    0.81   11.18  322   GRN
 Southern   20230603 09   89.19    1.55   36.47  255   GRN
#---------- -------- --  ------  ------  ------  --- ------
# Status: Green
# Hours to last foF2 observation: 0
#
Listings of past 5 hours:
Global SSNe
YYYYMMDD HH   SSNe     RMS    RMS%    #
-------- --  ------  ------  ------  ---
20230603 05   98.90    1.30   27.62  595
20230603 06   98.56    1.30   27.66  595
20230603 07   98.38    1.30   28.12  596
20230603 08   98.81    1.29   28.05  596
20230603 09   99.09    1.29   28.51  599
-------- --  ------  ------  ------  ---
Northern Hemisphere SSNe
YYYYMMDD HH   SSNe     RMS    RMS%    #
-------- --  ------  ------  ------  ---
20230603 05  105.51    0.81   11.14  319
20230603 06  105.42    0.81   11.14  320
20230603 07  106.18    0.82   11.17  320
20230603 08  107.58    0.81   11.08  320
20230603 09  108.71    0.81   11.18  322
-------- --  ------  ------  ------  ---
Southern Hemisphere SSNe
YYYYMMDD HH   SSNe     RMS    RMS%    #
-------- --  ------  ------  ------  ---
20230603 05   91.22    1.62   36.54  255
20230603 06   90.62    1.61   36.44  254
20230603 07   89.82    1.59   36.61  255
20230603 08   89.52    1.57   36.10  255
20230603 09   89.19    1.55   36.47  255
-------- --  ------  ------  ------  ---
 
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.

[ Home | About NWRA | Staff | Research Areas | Products ]

How to contact NWRA

Copyright © 1996-2023 NorthWest Research Associates, Inc.  All rights reserved.