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Enivaldo Bonelli bonelli@ponta-negra.com Federal University of Rio Grande do Norte (UFRN) - Brazil. SA13A-07. Forecasting GPS Scintillations For Low Latitude Stations, in Brazil, using Real-Time Space Weather Data. Definitions. S4 : Scintillation index on the satellite signal.
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Enivaldo Bonelli bonelli@ponta-negra.com Federal University of Rio Grande do Norte (UFRN) - Brazil SA13A-07 Forecasting GPS Scintillations For Low Latitude Stations, in Brazil, using Real-Time Space Weather Data.
Definitions • S4 : Scintillation index on the satellite signal. • <S4>: Average scintillation index, on the signal of all satellites at a given night (2100 through 0500 UT.) • KP : Sum of 3-hour estimated index of magnetic activity, KP , from 0 through 21 UT.
We plan to show that magnectic storms inhibt GPS scintillations at low magnetic latitudes. For this reason we do the following, in this paper: • Select indices of magnectic activity • Calculate averages of the Scintillation Index for each day for some months. • Check for correlation between the two.
A qualitative example for the October 2003 storm. The next figure shows a detail of the NOAA-SEC alerts time-line. This information is provided in real-time, so we can use it, at sunset, to predict the amount of scintillation at night.
NOAA/SEC ALERTS & WARNINGS OF MAGNETIC STORMS(Detail,) STORM DAYS 29-31 OCT 2003.
Paths of satellites. Size of the circles represent the scintillation intensity. Note that the first storm night (29 October) had few scintillations.Plot software by Ted Beach . 031029 <S4> = 0.31 031028 <S4> = 0.08
Calm versus Active night,in terms of Scintillations. WBP of same satellite, for October 28, 2003(calm) and Oct, 29(storm)
Behavior of Scintillations for October/2003. Notice the “Halloween Storm at end of month”
An alternative way to have real-time information on storm: The GOES geostationary satellites can measure, among other quantities, the component of the magnetic field paralell to the earth´s axis, Hp. See the consistency between the next figure and the alerts above.
GOES North component of the geomagnetic field as a parameter for forecasting scintillations
CONCLUSIONS • The magnetic storm forecast from several sources NOAA-SEC ALERTS, GOES HP, ESTIMATED KP FROM SEC, can be used, at local sunset to forecast scintillations for the whole night. • The average S4 for the whole night seems to be a suitable parameter from which to estimate the amount of scintillations. • The inverse correlation between Kp and <S4> seems to work even when we do not have storms.