Solar activity for the the past week was quiet, with three active regions appeared earlier (NOAA2681, 2682, and NOAA2683) with relatively stable magnetic configuration. Since NOAA 2681 already on the west, it was immediately dissapear into the far-side in the middle of the week, and left two other active regions (NOAA2682 and NOAA2683) remain on the Solar disk for the past weeek. For the rest of the week, those two active regions remain stable and remain quiet.
Geomagnet activities on September 29th – October 5th, 2017 were in active condition. The local response maximum K index was 3 from Biak station and the minimum Dst index reached -40 nT. The maximum Kp index was 4 on September 30th, 2017. On that date also substorm, the Ae index intensity was ≤1500 nT. The electron flux on September 29th – October 3rd, 2017 were at very high conditions around 10000 [/cm2/sec/sr], and the rest were at high conditions around 1000 [/cm2/sec/sr].
Ionosphere conditions in this week were betweeen quiet to minor level.
There was depression of foF2 more than 30% from its median value. The foF2 depressions were impacted to the radiowave propagation over the ionosphere which known as the MUF Depression. Also, the minimum frequencies (fmin) of the ionosphere in this week were in quiet conditions. The increment of fmin that could be a source of disturbance in the HF radio communication which known as a Shortwave Fadeout (SWF) or Radio Blackout (RB). Based on the ionospheric observations using GISTM over Bandung and Biak the scintillation (S4) condition for this week was in quiet to medium level with S4 value was between 0.25 and 0.5. The error positioning conditions were normal to medium levels conditions that determined by the index W values.
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