Analisis Pemgaruh Penetrasi ....... (Anwar Santoso et al.) 97 ANALISIS PENGARUH PENETRASI MEDAN LISTRIK LINTANG TINGGI KE LINTANG RENDAH TERHADAP IONOSFER SAAT BADAI GEOMAGNET (ANALYSIS OF THE ELECTRIC FIELD PENETRATION EFFECT FROM HIGH TO LOW LATITUDES ON THE IONOSPHERE DURING GEOMAGNETIC STORM) Anwar Santoso * , Dadang Nurmali, Mira Juangsih, Iyus Edi Rusnadi, Sri Ekawati, Anton Winarko, Siska Filawati Pusat Sains Antariksa LAPAN Jln. DR. Djundjunan 133 Bandung * Email: anwar.santoso@lapan.go.id Diterima 23 Juni 2016; Direvisi 12 Desember 2017; Disetujui 15 Desember 2017 ABSTRACT The influence of geomagnetic storms on the ionosphere in the equatorial and low latitudes can be either rising or falling value of the value foF2 with the different response delay time. The difference in response is one of them allegedly influenced by the modification of Equatorial Electrojet (EEJ) generated by the penetration of high latitude electric field towards the low latitude electric field and the equator. Therefore, this paper analyzes the influence of the high latitude penetration of electric current to the low latitude electric current towards the ionosphere response to Indonesia's current geomagnetic storms using the data foF2 BPAA Sumedang (SMD; 6,91 0 S; 106,83 0 E geographic coordinates or 16,55 0 S; 179,95 0 E magnetic coordinates) and data from the Biak geomagnetic field station (BIK; 1,08 0 S; 136,05 0 E geographic coordinates or 9,73 0 S; 207,39 0 E magnetic coordinates) in 2000-2001. The result showed that the injection of the electric field of the high latitudes to lower latitudes causing foF2 BPAA Sumedang to be disturbed. Onset of the foF2 disturbance in BPAA Sumedang started coincide with EEJ(HBIK-HDRW) and reached its minimum point with a time delay between 0 to 4 hours before and after Dst index reached the minimum point. For a delay time of 0 to 4 hours after the Dst index reached the minimum point, the results were in accordance with the research results from the prior research. However, for the time difference of between 0 to 4 hours before the Dst index reached the minimum point, the results differ from their results. Keywords: geomagnetic storms, ionosphere in the equatorial, equatorial electrojet (EEJ)