IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium
This research presents an annual and seasonal variations of spread F observed by Ionosonde. The c... more This research presents an annual and seasonal variations of spread F observed by Ionosonde. The comparative study equatorial Spread F (ESF) occurrences during minimum and maximum solar activity (2008-2011) has been analyzed using two ionosondes networks at Kototabang (0.2ºS, 100.3ºE, -10.4º magnetic latitude) and Tanjungsari (0.3°S, 100.35 ° E, 6.15 ° S, 108.4 ° E magnetic latitude), Indonesia. The occurrence of ESF was analyzed with solar F10.7 cm flux and Sunspot Number (SSN). The analysis shows annual and seasonal variation of ESFs, the maximum of percentages ESF shows during September Equinox and the minimum of percentages ESF during December solstice during 2008-2011 in Kototabang and Tanjungsari. The occurrences of ESF in post-midnight were more dominant than post-sunset in June solstice and December Solstice during solar activity minimum (2008-2010).
The Global Navigation Satellite System (GNSS) technologies have made significant contribution to ... more The Global Navigation Satellite System (GNSS) technologies have made significant contribution to seismology studies. Some processing strategies are well known, like real time PPP and DGPS techniques. These two methods have been widely used for GNSS based seismic activities monitoring. The first method requires accurate models of GNSS measurement errors to achieve accuracy in centimeter (cm) and need convergence time in order of minutes to hours. The second method need relative short distance of reference stations to reduce significantly measurement errors. To overcome disadvantages of such two methods, the variometric method was used to attain accuracy, but the method needs to be tested in the high ionospheric disturbance of equatorial region. During occurrences of plasma bubble, the radio signals from satellite passing through the ionosphere sometimes show rapid amplitude and phase variations called ionospheric scintillation. The occurrences of ionospheric scintillation could degrade the performance of systems and generate errors in received messages. In this study, variometric measurements are performed during the equinoctial month (March 2012) when the occurrence of scintillation was more intense. Results showed degradation of measurement accuracy during strong scintillation occurrences. The errors reached more than 1 m/s, especially for up-down measurement.
IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium, 2019
This research analyzed ionospheric irregularities and variability in the Equatorial Ionospheric A... more This research analyzed ionospheric irregularities and variability in the Equatorial Ionospheric Anomaly (EIA), particularly in the equatorward, southern and northern crest over Indonesia are characterized using GISTM (GPS Ionospheric Scintillation and TEC Monitor) receivers at low-latitude to St. Patrick’s storm occurred on 17 March 2015. The results show the temporal and spatial of ionospheric responses as seen by geomagnetic condition (Dst and Kp indices) and GISTM receivers (TEC variations and spatial ionospheric scintillation (S4 index) during storm period in March 2015 at four stations over Indonesia. The analysis shows that the EIA is significantly disturbed during main phase and recovery phase of storm period.
2017 XXXIInd General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS), 2017
We investigated a post-midnight Field-Aligned Irregularities (FAIs) event observed with the Equat... more We investigated a post-midnight Field-Aligned Irregularities (FAIs) event observed with the Equatorial Atmosphere Radar (EAR) at Kototabang (0.2 o S, 100.3 o E, dip lat. 10.4 o S) in Indonesia on the night of 9 July 2010, using a comprehensive dataset of both neutral and plasma parameters. We compared FAI echoes collocated with 630 nm airglow depletion detected by an all-sky imager. The thermospheric neutral winds and temperatures obtained by a Fabry-Perot interferometer at Kototabang and the altitudes of F-layer (h'F) observed with ionosondes at Kototabang, Chiang Mai, and Chumphon were also examined. We found that the 3-m scale post-midnight FAIs occurred within plasma bubbles. The convergence of the equatorward neutral winds happened in this particular event related to midnight temperature maximum (MTM) and that the equatorward winds in both northern and southern hemispheres could be responsible for the growth of plasma bubbles around midnight. The uplift of F-layer at low latitudes could increase the growth rate of the Rayleigh-Taylor instability. Eastward electric currents driven by the equatorward winds could also contribute to the generation of the irregularities at post-midnight.
The irregular plasma density and velocity fluctuations often occur in the Earth’s ionosphere regi... more The irregular plasma density and velocity fluctuations often occur in the Earth’s ionosphere regions. When radio signals propagate through that region, they cause a fade in received signal power known as scintillation. The generation of these plasma irregularities is one of the important manifestations of space weather. Recently, research of the mechanism and the morphology of plasma irregularities has progressed. In this study, we analyzed E and F region field aligned irregularities (FAI) observed by a VHF backscatter radar with operating frequency 47 MHz have been operated at Kototabang (0.20 S, 100.32E; dip lat 10.36S), Indonesia. Seasonal variation of E and F region field aligned irregularities observation compared with sporadic E (E s) and equatorial spread F (ESF) occurrences observed by ionosonde. The ionosonde provide various E and F region parameters such as the critical frequency of F 2 layer (foF2), the critical frequency of sporadic E layer (f oEs), and the maximum heigh...
Abstrak Tingkat gangguan ionosfer dapat diklasifikasikan menggunakan indeks W yang diturunkan dar... more Abstrak Tingkat gangguan ionosfer dapat diklasifikasikan menggunakan indeks W yang diturunkan dari data TEC global ionospheric map (GIM). Dalam skala indeks W, kondisi ionosfer dikelompokkan menjadi 4 kategori: tenang, aktif, menengah dan besar. Indeks gangguan ionosfer tersebut dirancang untuk pengguna GPS berdasarkan penyimpangan nilai TEC dari nilai TEC kondisi tenang. Tetapi belum diuji menggunakan data akurasi posisi GPS pada berbagai nilai indeks W sehingga belum dapat dijadikan pedoman operasional dalam penentuan posisi GPS. Makalah ini membahas hasil penelitian pengukuran posisi dengan metode precise point positioning GPS frekuensi tunggal di daerah lintang rendah pada beberapa kondisi ionosfer dalam skala W. Data GPS yang digunakan adalah dari pengamatan GPS di daerah lintang rendah yaitu stasiun NTUS Singapura. Sebagai pembanding telah digunakan juga data GPS dari daerah lintang tengah. Hasil penelitian menunjukkan bahwa pada kondisi aktivitas matahari masih tinggi untuk d...
This reseach has been done to know the correlation between spread F appearance and scintillation ... more This reseach has been done to know the correlation between spread F appearance and scintillation ionosphere on west region Indonesia. The method has been used is data interpretation using computational way, then all of data is processed using matlab software. The occurance of spread F was minimum in 2008 with it value respectively around 45%. In 2011 the spread F was beginning to increase with it value respectively around 70%. The occurance of ionospheric scintilation was minimum in 2010 with it value respectively around 13%. These occurances were due to a minimum phase of solar activity. In 2013 the scintilation was beginning to increase with it value respectively around 75% in which the occurance was selected for S4 ≥ 0,6. The correlation level between spread F and scintilation is medium, because the value of R aquals 0,4 this case is be affected by solar activity. The value of R is 0 (no correlation) at weak solar activity and 0,6 at high solar activity.
Total elektron contant in ionosphere is affected by several fastors, local time, solar aktivities... more Total elektron contant in ionosphere is affected by several fastors, local time, solar aktivities, geomagnetic disturbance, geographical latitude and longitude. This researh aims to observase level variation of total electron contant during solar eclipse over Indonesia on 9 March 2016. We analyzed GPS data from two GPS stations in different locations with different sun observation geographical latitude and longitude, the locations were Sulawesi station (CAMP) and Maluku station (CAMB). The method used in this research, was data interpretation method computationally, the whole data analyzed using matlab software R2008a. The values of daily TEC range from 20 TECU till 30 TECU. Although the value of TEC when solar total eclipse range from 10n TECU untill 20 TECU. The percentage of decreasing value of TEC when total solar eclipse than the daily value of TEC. Decreasing of TEC value between 20%-40%.
PROSIDING SEMINAR NASIONAL FISIKA (E-JOURNAL) SNF2017 UNJ, 2017
Perubahan kerapatan elektron di lapisan ionosfer dapat menyebabkan pembelokan sinyal satelit kare... more Perubahan kerapatan elektron di lapisan ionosfer dapat menyebabkan pembelokan sinyal satelit karena lapisan ionosfer bersifat medium dispersif pada frekuensi radio satelit. Kondisi kerapatan elektron dan ion di lapisan ionosfer meningkat akibat adanya peningkatan aktivitas matahari dan akan berdampak pada propagasi gelombang radio dari satelit ke penerima, yaitu dapat menyebabkan perlambatan (delay). Delay tersebut berdampak pada pergeseran tingkat akurasi pengukuran posisi pada sistem satelit navigasi GNSS (Global Navigation Satellite System). Pada tanggal 10 September 2014 terjadi peristiwa flare X1.6 pada pukul 17:45 UT yang disertai dengan pelepasan masa korona (CME). Akibatnya, pada tanggal 12 September 2014 terjadi badai geomagnet kategori kuat. Respon ionosfer terhadap badai geomagnet tersebut telah menyebabkan badai positif karena terjadi peningkatan kandungan elektron. Dari hasil pengamatan TEC menggunakan GISTM Bandung dan Kupang terjadi peningkatan dengan simpangan maksimum TEC terhadap kondisi tenangnya mencapai 28 TEC Unit dari pengamatan Bandung dan mencapai 35 TEC Unit dari pengamatan Kupang. Frekuensi kritis lapisan F ionosfer (foF2) juga mengalami peningkatan saat terjadi badai geomagnet dengan kenaikan sekitar 4,5 MHz dari pengamatan ionsonde CADI Kupang. Hasil analisis pengukuran posisi absolute dari GPS stasiun tetap Darwin Australia saat badai geomagnet fase utama tanggal 12 September 2014 menyebabkan kesalahan vertikal mencapai lebih dari 20 meter.
Journal of Geophysical Research: Space Physics, 2017
Post-midnight field-aligned irregularities occur within plasma bubbles and coincide with kilomete... more Post-midnight field-aligned irregularities occur within plasma bubbles and coincide with kilometer-scale plasma density irregularities. o Equatorward thermospheric winds at low latitudes could affect generation of postmidnight field-aligned irregularities. o Equatorward thermospheric winds associated with midnight temperature maximum could increase the growth rate of Rayleigh-Taylor instability.
A total solar eclipse occurred over Indonesia in the morning hours on 9 March 2016. Ionisations i... more A total solar eclipse occurred over Indonesia in the morning hours on 9 March 2016. Ionisations in the ionosphere which is associated with the solar radiation during the total eclipse provided a good opportunity to study the ionospheric irregularities. Using global navigation satellite system (GNSS) data taken from dual-frequency receivers in Manado, we investigated and analysed the total electron content (TEC) perturbations with a time resolution of 60 s to reveal ionospheric irregularities during total eclipse. Result showed that TEC conditions based on IPP were decreased during solar eclipse on March 9, comparing with the neighbour day. The maximum percentage deviation (DTEC) from the average value during eclipse period, 00:00 - 02:40 UT reach -41.5%. The duration of maximum decrement in TEC occurs were around 2-30 minutes after the maximum obscuration.
Journal of Geophysical Research: Space Physics, 2016
We investigate the geospace response to the 2015 St. Patrickˈs Day storm leveraging on instrument... more We investigate the geospace response to the 2015 St. Patrickˈs Day storm leveraging on instruments spread over Southeast Asia (SEA), covering a wide longitudinal sector of the low-latitude ionosphere. A regional characterization of the storm is provided, identifying the peculiarities of ionospheric irregularity formation. The novelties of this work are the characterization in a broad longitudinal range and the methodology relying on the integration of data acquired by Global Navigation Satellite System (GNSS) receivers, magnetometers, ionosondes, and Swarm satellites. This work is a legacy of the project EquatoRial Ionosphere Characterization in Asia (ERICA). ERICA aimed to capture the features of both crests of the equatorial ionospheric anomaly (EIA) and trough (EIT) by means of a dedicated measurement campaign. The campaign lasted from March to October 2015 and was able to observe the ionospheric variability causing effects on radio systems, GNSS in particular. The multiinstrumental and multiparametric observations of the region enabled an in-depth investigation of the response to the largest geomagnetic storm of the current solar cycle in a region scarcely reported in literature. Our work discusses the comparison between northern and southern crests of the EIA in the SEA region. The observations recorded positive and negative ionospheric storms, spread F conditions, scintillation enhancement and inhibition, and total electron content variability. The ancillary information on the local magnetic field highlights the variety of ionospheric perturbations during the different storm phases. The combined use of ionospheric bottomside, topside, and integrated information points out how the storm affects the F layer altitude and the consequent enhancement/suppression of scintillations.
. We report our investigation of ionospheric effects due to the passage of an annular solar eclip... more . We report our investigation of ionospheric effects due to the passage of an annular solar eclipse over Southeast Asia on 26 December 2019, using multiple set of observations. Two ionosondes (one at Kototabang and another at Pontianak) were used to measure dynamical changes in the ionospheric layer during the event. A network of ground-based GPS receiver stations in Indonesia were used to derive the distribution of total electron content (TEC) over the region. In addition, extreme ultraviolet (EUV) images of the Sun from the Atmospheric Imaging Assembly (AIA) instrument on board the Solar Dynamics Observatory (SDO) satellite were also analyzed to determine possible impacts of solar active regions on the changes that occurred in the ionosphere during the eclipse. We found −1.67 MHz and −1.58 MHz reduction (23.2 % and 22.4 % relative reduction) in foF2 during the solar eclipse over Kototabang and Pontianak, respectively. The respective TEC reduction over Kototabang and Pontianak during the eclipse was −4.34 TECU and −5.45 TECU (24.9 % and 27.9 % relative reduction). Overall, there was 34–36 minutes delay from maximum eclipse until minimum foF2 was reached at these two locations. The corresponding time delays for eclipse-related TEC reduction at these two locations were 40 minutes and 16 minutes, respectively. The ionospheric F-layer was found to descend with a speed of 9–19 m/s during the first half of the eclipse period. We also found an apparent rise of the ionospheric F-layer height near the end of the solar eclipse period, equivalent to vertical drift velocity of 44–47 m/s. The GPS TEC data mapping along a set of cross-sectional cut lines indicate that the greatest TEC reduction actually occurred to the north of the solar eclipse path, opposite of the direction from which the lunar shadow fell. As the central path of the solar eclipse was located just to the north of the southern equatorial ionization anomaly (EIA) crest, it is suspected that such a peculiar TEC reduction pattern was caused by plasma flow associated with the equatorial fountain effect. Net perturbations of TEC were also computed and analyzed, which revealed the presence some wavelike fluctuations associated with the solar eclipse event. Some of the observed TEC perturbation patterns that propagated with a velocity matching the lunar shadow may be explained in terms of non-uniform EUV illumination that arose as various active regions on the Sun went obstructed and unobstructed during the eclipse. The remaining wavelike features are likely to be traveling ionospheric disturbances (TIDs) driven by acoustic-gravity waves (AGWs), generated by the passage of the solar eclipse on top of other diurnal factors.
IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium
This research presents an annual and seasonal variations of spread F observed by Ionosonde. The c... more This research presents an annual and seasonal variations of spread F observed by Ionosonde. The comparative study equatorial Spread F (ESF) occurrences during minimum and maximum solar activity (2008-2011) has been analyzed using two ionosondes networks at Kototabang (0.2ºS, 100.3ºE, -10.4º magnetic latitude) and Tanjungsari (0.3°S, 100.35 ° E, 6.15 ° S, 108.4 ° E magnetic latitude), Indonesia. The occurrence of ESF was analyzed with solar F10.7 cm flux and Sunspot Number (SSN). The analysis shows annual and seasonal variation of ESFs, the maximum of percentages ESF shows during September Equinox and the minimum of percentages ESF during December solstice during 2008-2011 in Kototabang and Tanjungsari. The occurrences of ESF in post-midnight were more dominant than post-sunset in June solstice and December Solstice during solar activity minimum (2008-2010).
The Global Navigation Satellite System (GNSS) technologies have made significant contribution to ... more The Global Navigation Satellite System (GNSS) technologies have made significant contribution to seismology studies. Some processing strategies are well known, like real time PPP and DGPS techniques. These two methods have been widely used for GNSS based seismic activities monitoring. The first method requires accurate models of GNSS measurement errors to achieve accuracy in centimeter (cm) and need convergence time in order of minutes to hours. The second method need relative short distance of reference stations to reduce significantly measurement errors. To overcome disadvantages of such two methods, the variometric method was used to attain accuracy, but the method needs to be tested in the high ionospheric disturbance of equatorial region. During occurrences of plasma bubble, the radio signals from satellite passing through the ionosphere sometimes show rapid amplitude and phase variations called ionospheric scintillation. The occurrences of ionospheric scintillation could degrade the performance of systems and generate errors in received messages. In this study, variometric measurements are performed during the equinoctial month (March 2012) when the occurrence of scintillation was more intense. Results showed degradation of measurement accuracy during strong scintillation occurrences. The errors reached more than 1 m/s, especially for up-down measurement.
IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium, 2019
This research analyzed ionospheric irregularities and variability in the Equatorial Ionospheric A... more This research analyzed ionospheric irregularities and variability in the Equatorial Ionospheric Anomaly (EIA), particularly in the equatorward, southern and northern crest over Indonesia are characterized using GISTM (GPS Ionospheric Scintillation and TEC Monitor) receivers at low-latitude to St. Patrick’s storm occurred on 17 March 2015. The results show the temporal and spatial of ionospheric responses as seen by geomagnetic condition (Dst and Kp indices) and GISTM receivers (TEC variations and spatial ionospheric scintillation (S4 index) during storm period in March 2015 at four stations over Indonesia. The analysis shows that the EIA is significantly disturbed during main phase and recovery phase of storm period.
2017 XXXIInd General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS), 2017
We investigated a post-midnight Field-Aligned Irregularities (FAIs) event observed with the Equat... more We investigated a post-midnight Field-Aligned Irregularities (FAIs) event observed with the Equatorial Atmosphere Radar (EAR) at Kototabang (0.2 o S, 100.3 o E, dip lat. 10.4 o S) in Indonesia on the night of 9 July 2010, using a comprehensive dataset of both neutral and plasma parameters. We compared FAI echoes collocated with 630 nm airglow depletion detected by an all-sky imager. The thermospheric neutral winds and temperatures obtained by a Fabry-Perot interferometer at Kototabang and the altitudes of F-layer (h'F) observed with ionosondes at Kototabang, Chiang Mai, and Chumphon were also examined. We found that the 3-m scale post-midnight FAIs occurred within plasma bubbles. The convergence of the equatorward neutral winds happened in this particular event related to midnight temperature maximum (MTM) and that the equatorward winds in both northern and southern hemispheres could be responsible for the growth of plasma bubbles around midnight. The uplift of F-layer at low latitudes could increase the growth rate of the Rayleigh-Taylor instability. Eastward electric currents driven by the equatorward winds could also contribute to the generation of the irregularities at post-midnight.
The irregular plasma density and velocity fluctuations often occur in the Earth’s ionosphere regi... more The irregular plasma density and velocity fluctuations often occur in the Earth’s ionosphere regions. When radio signals propagate through that region, they cause a fade in received signal power known as scintillation. The generation of these plasma irregularities is one of the important manifestations of space weather. Recently, research of the mechanism and the morphology of plasma irregularities has progressed. In this study, we analyzed E and F region field aligned irregularities (FAI) observed by a VHF backscatter radar with operating frequency 47 MHz have been operated at Kototabang (0.20 S, 100.32E; dip lat 10.36S), Indonesia. Seasonal variation of E and F region field aligned irregularities observation compared with sporadic E (E s) and equatorial spread F (ESF) occurrences observed by ionosonde. The ionosonde provide various E and F region parameters such as the critical frequency of F 2 layer (foF2), the critical frequency of sporadic E layer (f oEs), and the maximum heigh...
Abstrak Tingkat gangguan ionosfer dapat diklasifikasikan menggunakan indeks W yang diturunkan dar... more Abstrak Tingkat gangguan ionosfer dapat diklasifikasikan menggunakan indeks W yang diturunkan dari data TEC global ionospheric map (GIM). Dalam skala indeks W, kondisi ionosfer dikelompokkan menjadi 4 kategori: tenang, aktif, menengah dan besar. Indeks gangguan ionosfer tersebut dirancang untuk pengguna GPS berdasarkan penyimpangan nilai TEC dari nilai TEC kondisi tenang. Tetapi belum diuji menggunakan data akurasi posisi GPS pada berbagai nilai indeks W sehingga belum dapat dijadikan pedoman operasional dalam penentuan posisi GPS. Makalah ini membahas hasil penelitian pengukuran posisi dengan metode precise point positioning GPS frekuensi tunggal di daerah lintang rendah pada beberapa kondisi ionosfer dalam skala W. Data GPS yang digunakan adalah dari pengamatan GPS di daerah lintang rendah yaitu stasiun NTUS Singapura. Sebagai pembanding telah digunakan juga data GPS dari daerah lintang tengah. Hasil penelitian menunjukkan bahwa pada kondisi aktivitas matahari masih tinggi untuk d...
This reseach has been done to know the correlation between spread F appearance and scintillation ... more This reseach has been done to know the correlation between spread F appearance and scintillation ionosphere on west region Indonesia. The method has been used is data interpretation using computational way, then all of data is processed using matlab software. The occurance of spread F was minimum in 2008 with it value respectively around 45%. In 2011 the spread F was beginning to increase with it value respectively around 70%. The occurance of ionospheric scintilation was minimum in 2010 with it value respectively around 13%. These occurances were due to a minimum phase of solar activity. In 2013 the scintilation was beginning to increase with it value respectively around 75% in which the occurance was selected for S4 ≥ 0,6. The correlation level between spread F and scintilation is medium, because the value of R aquals 0,4 this case is be affected by solar activity. The value of R is 0 (no correlation) at weak solar activity and 0,6 at high solar activity.
Total elektron contant in ionosphere is affected by several fastors, local time, solar aktivities... more Total elektron contant in ionosphere is affected by several fastors, local time, solar aktivities, geomagnetic disturbance, geographical latitude and longitude. This researh aims to observase level variation of total electron contant during solar eclipse over Indonesia on 9 March 2016. We analyzed GPS data from two GPS stations in different locations with different sun observation geographical latitude and longitude, the locations were Sulawesi station (CAMP) and Maluku station (CAMB). The method used in this research, was data interpretation method computationally, the whole data analyzed using matlab software R2008a. The values of daily TEC range from 20 TECU till 30 TECU. Although the value of TEC when solar total eclipse range from 10n TECU untill 20 TECU. The percentage of decreasing value of TEC when total solar eclipse than the daily value of TEC. Decreasing of TEC value between 20%-40%.
PROSIDING SEMINAR NASIONAL FISIKA (E-JOURNAL) SNF2017 UNJ, 2017
Perubahan kerapatan elektron di lapisan ionosfer dapat menyebabkan pembelokan sinyal satelit kare... more Perubahan kerapatan elektron di lapisan ionosfer dapat menyebabkan pembelokan sinyal satelit karena lapisan ionosfer bersifat medium dispersif pada frekuensi radio satelit. Kondisi kerapatan elektron dan ion di lapisan ionosfer meningkat akibat adanya peningkatan aktivitas matahari dan akan berdampak pada propagasi gelombang radio dari satelit ke penerima, yaitu dapat menyebabkan perlambatan (delay). Delay tersebut berdampak pada pergeseran tingkat akurasi pengukuran posisi pada sistem satelit navigasi GNSS (Global Navigation Satellite System). Pada tanggal 10 September 2014 terjadi peristiwa flare X1.6 pada pukul 17:45 UT yang disertai dengan pelepasan masa korona (CME). Akibatnya, pada tanggal 12 September 2014 terjadi badai geomagnet kategori kuat. Respon ionosfer terhadap badai geomagnet tersebut telah menyebabkan badai positif karena terjadi peningkatan kandungan elektron. Dari hasil pengamatan TEC menggunakan GISTM Bandung dan Kupang terjadi peningkatan dengan simpangan maksimum TEC terhadap kondisi tenangnya mencapai 28 TEC Unit dari pengamatan Bandung dan mencapai 35 TEC Unit dari pengamatan Kupang. Frekuensi kritis lapisan F ionosfer (foF2) juga mengalami peningkatan saat terjadi badai geomagnet dengan kenaikan sekitar 4,5 MHz dari pengamatan ionsonde CADI Kupang. Hasil analisis pengukuran posisi absolute dari GPS stasiun tetap Darwin Australia saat badai geomagnet fase utama tanggal 12 September 2014 menyebabkan kesalahan vertikal mencapai lebih dari 20 meter.
Journal of Geophysical Research: Space Physics, 2017
Post-midnight field-aligned irregularities occur within plasma bubbles and coincide with kilomete... more Post-midnight field-aligned irregularities occur within plasma bubbles and coincide with kilometer-scale plasma density irregularities. o Equatorward thermospheric winds at low latitudes could affect generation of postmidnight field-aligned irregularities. o Equatorward thermospheric winds associated with midnight temperature maximum could increase the growth rate of Rayleigh-Taylor instability.
A total solar eclipse occurred over Indonesia in the morning hours on 9 March 2016. Ionisations i... more A total solar eclipse occurred over Indonesia in the morning hours on 9 March 2016. Ionisations in the ionosphere which is associated with the solar radiation during the total eclipse provided a good opportunity to study the ionospheric irregularities. Using global navigation satellite system (GNSS) data taken from dual-frequency receivers in Manado, we investigated and analysed the total electron content (TEC) perturbations with a time resolution of 60 s to reveal ionospheric irregularities during total eclipse. Result showed that TEC conditions based on IPP were decreased during solar eclipse on March 9, comparing with the neighbour day. The maximum percentage deviation (DTEC) from the average value during eclipse period, 00:00 - 02:40 UT reach -41.5%. The duration of maximum decrement in TEC occurs were around 2-30 minutes after the maximum obscuration.
Journal of Geophysical Research: Space Physics, 2016
We investigate the geospace response to the 2015 St. Patrickˈs Day storm leveraging on instrument... more We investigate the geospace response to the 2015 St. Patrickˈs Day storm leveraging on instruments spread over Southeast Asia (SEA), covering a wide longitudinal sector of the low-latitude ionosphere. A regional characterization of the storm is provided, identifying the peculiarities of ionospheric irregularity formation. The novelties of this work are the characterization in a broad longitudinal range and the methodology relying on the integration of data acquired by Global Navigation Satellite System (GNSS) receivers, magnetometers, ionosondes, and Swarm satellites. This work is a legacy of the project EquatoRial Ionosphere Characterization in Asia (ERICA). ERICA aimed to capture the features of both crests of the equatorial ionospheric anomaly (EIA) and trough (EIT) by means of a dedicated measurement campaign. The campaign lasted from March to October 2015 and was able to observe the ionospheric variability causing effects on radio systems, GNSS in particular. The multiinstrumental and multiparametric observations of the region enabled an in-depth investigation of the response to the largest geomagnetic storm of the current solar cycle in a region scarcely reported in literature. Our work discusses the comparison between northern and southern crests of the EIA in the SEA region. The observations recorded positive and negative ionospheric storms, spread F conditions, scintillation enhancement and inhibition, and total electron content variability. The ancillary information on the local magnetic field highlights the variety of ionospheric perturbations during the different storm phases. The combined use of ionospheric bottomside, topside, and integrated information points out how the storm affects the F layer altitude and the consequent enhancement/suppression of scintillations.
. We report our investigation of ionospheric effects due to the passage of an annular solar eclip... more . We report our investigation of ionospheric effects due to the passage of an annular solar eclipse over Southeast Asia on 26 December 2019, using multiple set of observations. Two ionosondes (one at Kototabang and another at Pontianak) were used to measure dynamical changes in the ionospheric layer during the event. A network of ground-based GPS receiver stations in Indonesia were used to derive the distribution of total electron content (TEC) over the region. In addition, extreme ultraviolet (EUV) images of the Sun from the Atmospheric Imaging Assembly (AIA) instrument on board the Solar Dynamics Observatory (SDO) satellite were also analyzed to determine possible impacts of solar active regions on the changes that occurred in the ionosphere during the eclipse. We found −1.67 MHz and −1.58 MHz reduction (23.2 % and 22.4 % relative reduction) in foF2 during the solar eclipse over Kototabang and Pontianak, respectively. The respective TEC reduction over Kototabang and Pontianak during the eclipse was −4.34 TECU and −5.45 TECU (24.9 % and 27.9 % relative reduction). Overall, there was 34–36 minutes delay from maximum eclipse until minimum foF2 was reached at these two locations. The corresponding time delays for eclipse-related TEC reduction at these two locations were 40 minutes and 16 minutes, respectively. The ionospheric F-layer was found to descend with a speed of 9–19 m/s during the first half of the eclipse period. We also found an apparent rise of the ionospheric F-layer height near the end of the solar eclipse period, equivalent to vertical drift velocity of 44–47 m/s. The GPS TEC data mapping along a set of cross-sectional cut lines indicate that the greatest TEC reduction actually occurred to the north of the solar eclipse path, opposite of the direction from which the lunar shadow fell. As the central path of the solar eclipse was located just to the north of the southern equatorial ionization anomaly (EIA) crest, it is suspected that such a peculiar TEC reduction pattern was caused by plasma flow associated with the equatorial fountain effect. Net perturbations of TEC were also computed and analyzed, which revealed the presence some wavelike fluctuations associated with the solar eclipse event. Some of the observed TEC perturbation patterns that propagated with a velocity matching the lunar shadow may be explained in terms of non-uniform EUV illumination that arose as various active regions on the Sun went obstructed and unobstructed during the eclipse. The remaining wavelike features are likely to be traveling ionospheric disturbances (TIDs) driven by acoustic-gravity waves (AGWs), generated by the passage of the solar eclipse on top of other diurnal factors.
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