S4 Index
{{Short description|Parameter used to measure ionospheric disturbances}}
{{one source |date=March 2024}}
The Index is a standard index used to measure ionospheric disturbances. It is defined as the ratio of the standard deviation of signal intensity to the average signal intensity.{{cite book |last1=Basu |first1=Santimay |last2=Basu |first2=Sunanda |title=Scintillation technique for probing Ionospheric irregularities |page=128}}
Real Time data
This parameter is displayed in real time by many institutions:
- [http://gps.ece.cornell.edu/scintplot_aopr.html at Arecibo Observatory]
- [http://gps.ece.cornell.edu/scintplot.html at Cornell University]
- [http://www2.inpe.br/climaespacial/portal/sci-inicio/ at INPE, in Brasil]