DETERMINATION OF REGIONAL IONOSPHERE INDEX “Tâ€

Abstract

F2 layer critical frequency (foF2), is varied following the sunspot numbers variation. The sunspot numbers can be compared with foF2 to use as MUF predictors, but the ionosphere condition is not only related to sunspot numbers. As the solution it is used the ionosphere index (T index) derived from the ionosphere observations results during some solar cycles in various places and connect them with sunspot numbers. In this research we derived the T regional index determination methods, assuming that the relationship between foF2 with sunspot number is linear. The value of foF2 used is the monthly median average, while the sunspot numbers is annual average (R12). By several times calculation using different weighted sunspot number value, it obtains different linear equation between foF2 and T index. This method was derived using data foF2 Tanjungsari 1998 until 2008, and Vanimo in 1986 up to 2009 that each represent areas of Western and eastern Indonesia. The results was a linier equation between foF2 and indeks T for both area every month. The calculation results using these methods showed that regional T index of Tanjungsari as well as Vanimo had characteristics that in accordance with the global T index as well as R12 T index, with the regional T index value > the global T index for both places.