This study compared the post-sunset and post-midnight equatorial spread-F (ESF) characteristics as well as their association with equatorial plasma bubbles (EPBs) and ionospheric scintillation. The occurrence of ESF was studied by looking at the percentage of monthly event intensity as well as seasonal variations during minimum solar activity (2008). This research used ionosonde, all-sky imager (ASI) and GPS receivers mounted on Kototabang (0.2°S, 100.3°E, -10.4° magnetic latitude) Indonesia. The occurrence of ESF were identified with two events, namely post-sunset (18:00-00:00 LT) and post-midnight (00:00-06:00 LT). From the observations, the percentage gained for ESF occurrence was 39.68%, with 18.01% for post-sunset and 21.67% for post-midnight, respectively. This suggests that the incidence of post-midnight ESF was greater than in post-sunset events during 2008. The occurrence of post-midnight ESF was more dominant in the summer solstice (May-July) with a value of 72.34%, while for post-sunset in equinoxes (Augustus- October) with a value of 62.79%. The correlation between the occurrence of ESF and EPBs show that post-sunset and post-midnight ESF averages are observed about ~30 minutes and ~60 minutes since the start of the EPBs. This reinforces the notion that one of the causes of the ESF is the instability that occurs below the elevation of the ionosphere F-layer indicating a movement of EPBs from the bottom-up processing. The occurrence of ESF has an impact on the incidence of scintillation, where at post-sunset ESF has a direct effect, whereas at post-midnight ESF it takes ~90 minutes to form scintillation, respectively.
Monitoring of ionospheric parameters (such as Total Electron Content and scintillation) is of great importance as it
affects and contributes to the errors encountered by radio signals. It thus requires constant measurements to avoid
disastrous situation for space agencies, parastatals and departments that employ GNSS applications in their daily
operations. The research objective is to have a better understanding of the behaviour of ionospheric scintillation at midlatitude
as it threatens the performances of satellite communication, navigation systems and military operations. This
paper adopts seasonal ionospheric scintillation scenario. The mid-latitude investigation of ionospheric effect of
scintillation was conducted during the increasing solar activity from 2011-2015.
Ionospheric scintillation data were obtained from four ionospheric monitoring stations located at mid-latitude (i.e
Shenzhen North Station, Beijing Changping North Station Branch, Beijing North Station and Beijing Miyun ground
Station). The data was collected from January 2011 to December 2015. There were absence of data due to software
problem or system failure at some locations. The scintillation phenomenon was computed using Global Ionospheric
Scintillation and TEC Monitoring Model. There are four seasons which existed in China namely: Spring, Summer,
Autumn and Winter. The relationship between TEC, amplitude and phase scintillation were observed for each of these
The results indicated that the weak amplitude scintillation was observed as against phase scintillation which was high.
Phase scintillation was gradually enhanced from 2011 to 2012 and later declined till 2014. TEC was also at peak around
00:00-10:00 UT (08:00-18:00 LT). The seasonal events temporal density characteristics comply with solar cycle
prediction as such it ascended from 2011 to 2013 and then scintillation parameters declined significantly afterwards.
This research investigated the potential of the upper atmosphere layer height changes as precursor of the Padang
Earthquake on 30 September 2009. We analyzed the occurrence of atmospheric gravity wave (AGW) in all-sky imager
(ASI) images and h’F in ionosonde mounted on Kototabang (0.2°S, 100.3°E, -10.4° magnetic latitude) Indonesia from
seven days before and after the earthquake and found that there was an unusual evening in h’F variation on 24 and 29
September 2009. A positive h’F deviation on 24 and 29 September 2009 are with a maximum value of 42 and 31.5. For
both these dates, the maximum h’F value reached 234 km and 261 km at 00:30 LT and 20:30 LT with the median value
of 192 km and 229.5 km, respectively. The increase in h’F on 24 September 2009 before the midnight was caused by
encouragement from AGW observed at a wavelength of OH bands (~86 km) that happened a few minutes earlier. While
the increase in h’F on 29 September 2009, suspected to be caused by the emergence of the AGW, though it cannot be
proven because ASI does not operate due to rainy weather over Kototabang. For Dst index during the month of
September 2009, there is nothing worth under -50 nT, this means a change of altitude h’F six and one days before the
earthquake is not caused by the influence of magnetic storm but caused by AGW resulting from the epicenter.