The penultimate sentence of the Measures section should have cited reference 41 instead of 39. In... more The penultimate sentence of the Measures section should have cited reference 41 instead of 39. In the Funding section, the name of the funder CIMVHR should be listed as "Canadian Institute for Military and Veteran Health Research (CIMVHR)".
The 2nd Equatorial Plasma Bubble (EPB) workshop, funded by the Institute of Geology and Geophysic... more The 2nd Equatorial Plasma Bubble (EPB) workshop, funded by the Institute of Geology and Geophysics, Chinese Academy of Sciences, and the National Natural Science Foundation of China, took place in Beijing, China during September 13-15, 2019. The EPB workshop belongs to a conference series that began in 2016 in Nagoya, Japan at the Institute for Space-Earth Environmental Research, Nagoya University, resulting in a special issue of Progress in Earth and Planetary Science that focused on EPBs. The main goal of the series is to organize in-depth discussion by scientists working on ionospheric irregularities, and solve the scientific challenges in EPB and ionospheric scintillation forecasting. The 2nd EPB workshop gathered almost 60 scientists from seven countries. A total of 20 invited and contributing papers focusing on ionospheric irregularities and scintillations were presented. Here we briefly comment on 10 papers included in this special issue.
Previous studies have proposed that both the thermospheric neutral wind and the equatorial electr... more Previous studies have proposed that both the thermospheric neutral wind and the equatorial electrojet (EEJ) near sunset play important roles in the pre‐reversal enhancement (PRE) mechanism. In this study, we have used observations made in the equatorial region of Southeast Asia during March–April and September–October in 2010–2013 to investigate influences of the eastward neutral wind and the EEJ on the PRE’s strength. Our analysis employs data collected by the Gravity Field and Steady‐State Ocean Circulation Explorer (GOCE) satellite to determine the zonal (east‐west direction) neutral wind at an altitude of ~250 km (bottomside F region) at longitudes of 90°–130°E in the dusk sector. Three ionosondes, at Chumphon (dip lat.: 3.0°N) in Thailand, at Bac Lieu (dip lat.: 1.7°N) in Vietnam, and at Cebu (dip lat.: 3.0°N) in Philippines, provided the data we have used to derive the PRE strength. Data from two magnetometers — at Phuket (dip lat.: 0.1°S) in Thailand and at Kototabang (dip lat.: 10.3°S) in Indonesia — were used to estimate the EEJ strength. Our study is focused particularly on days with magnetically quiet conditions. We have found that the eastward neutral wind and the EEJ are both closely correlated with the PRE; their cross‐correlation coefficients with it are, respectively, 0.42 and 0.47. Their relationship with each other is weaker: the cross‐correlation coefficient between the eastward neutral wind and the EEJ is just 0.26. Our findings suggest that both the eastward neutral wind and the EEJ near sunset are involved in the PRE mechanism. Based on the weak relationship between these two parameters, however, they appear to be significantly independent of each other. Thus, the wind and the EEJ are likely to be influencing the PRE magnitude independently, their effects balancing each other.
Ground-Based Augmentation System (GBAS) is a GNSS augmentation system that meets International Ci... more Ground-Based Augmentation System (GBAS) is a GNSS augmentation system that meets International Civil Aviation Organization (ICAO) requirements to support precision approach and landing. GBAS is based on the local differential GNSS technique with reference stations located around the airport to provide necessary integrity and accuracy. The performance of the GBAS system can be affected by the gradient in the ionospheric delay between the aircraft and the reference stations. A nominal ionospheric gradient, which is bounded by a conservative error bound, is represented by a parameter σvig. σvig was commonly determined using station pair to GNSS Continuous Operating Reference Station (CORS) data. The station pair method is susceptible to doubling of receiver bias error and is not suitable with the CORS conditions in Indonesia. We propose a satellite pair method that is found to be more suitable for the CORS network over Indonesia which is centered in Java and Sumatra islands. The value ...
Observations of Ionosphere as a wireless channel using channel sounder method is needed to obtain... more Observations of Ionosphere as a wireless channel using channel sounder method is needed to obtain the channel parameters characteristic. The Sliding Correlator Channel Sounder is known as a popular technique with low complexity and relatively low cost. Similar to the sliding correlator, Software Define Radio (SDR) device is one of the popular inexpensive platforms for implementing the system into the real world. Implementation of the sliding correlator channel sounder technique in the SDR platform will increase the ionosphere channel measurement system's advantages as an effort to obtain the dynamic of ionospheric channel characteristics. However, to guarantee the designed system able to works according to the SDR device specifications and meet the system performance targets, the optimization should be done. This paper discusses the design of a sliding correlator channel sounder system to observe the characteristics of ionosphere channels using SDR with consideration to the limitation of the hardware specification and the system performance target based on the recommendation of ionospheric channel characteristics ITU-R F.1487. Simulation and over-the-air test from the design results show that the expected system performance can be met and realized in a real-world implementation.
We used ionosondes in Chumphon (CPN) (10.72°N, 99.37°E; Mag. Lat: 3°N), Thailand; Bac Lieu (BCL) ... more We used ionosondes in Chumphon (CPN) (10.72°N, 99.37°E; Mag. Lat: 3°N), Thailand; Bac Lieu (BCL) (9.30°N, 105.71°E; Mag. Lat: 1.5°N), Vietnam; and Cebu (CEB) (10.35°N, 123.91°E; Mag. Lat: 3.09°N), Philippines during equinox seasons from 2010 to 2016 to develop a forecast technique for equatorial spread F or plasma bubble generation. We considered that enhancement of vertical E ×B drift after sunset in the equatorial region, so-called pre-reversal enhancement (PRE), is a primary factor for plasma bubble generation. We then used a "PRE threshold" to determine ESF whether generates or not. We collected 264, 121, and 206 nights for CPN, BCL, and CEB ionosondes, respectively. We used change of h'f in time ( dh'f/dt) during 18-19 LT from three ionosonde sites as a proxy for the vertical drift. The threshold is simply defined with a average value of vertical drifts obtained from all stations, and the value is 24 m/s. We defined the PRE 24 m/s and PRE < 24 m/s for the E...
Equatorial plasma bubbles (EPB) adalah fenomena ketidakteraturan di lapisan ionosfer bumi akibat ... more Equatorial plasma bubbles (EPB) adalah fenomena ketidakteraturan di lapisan ionosfer bumi akibat perbedaan kerapatan elektron antara dua lapisan di dalamnya. Berdasarkan perbedaan kerapatan elektron, lapisan ionosfer terdiri dari lapisan D, lapisan E, dan lapisan F. Pada lapisan F, terjadi penipisan lapisan akibat adanya kenaikan bagian bawah lapisan dengan kerapatan elektron lebih kecil yang mendorong ke atas, ke lapisan dengan kerapatan elektron lebih besar melalui mekanisme ketakstabilan Rayleigh–Taylor. Fenomena tersebut dikenal dengan istilah plasma bubbles (gelembung plasma). Pembentukan gelembung plasma ini terjadi di sektor ekuator, sesaat setelah matahari tenggelam. Kajian tentang fenomena ini menarik karena EPB dapat menyebabkan perubahan kerapatan elektron secara cepat dan berpengaruh terhadap penjalaran sinyal gelombang radio yang melewati lapisan ionosfer baik berupa gangguan dalam amplitudo maupun fasenya, biasa dikenal sebagai sintilasi. Salah satu parameter yang menj...
Equatorial plasma bubbles (EPBs) can cause rapid fluctuations in amplitude and phase of radio sig... more Equatorial plasma bubbles (EPBs) can cause rapid fluctuations in amplitude and phase of radio signals traversing the ionosphere and in turn produce serious ionospheric scintillations and disrupt satellite-based communication links. Whereas numerous studies on the generation and evolution of EPBs have been performed, the prediction of EPB and ionospheric scintillation occurrences still remains unresolved. The generalized Rayleigh–Taylor (R–T) instability has been widely accepted as the physical mechanism responsible for the generation of EPBs. But how the factors, which seed the development of R–T instability and control the dynamics of EPBs and resultant ionospheric scintillations, change on a short-term basis are not clear. In the East and Southeast Asia, there exist significant differences in the generation rates of EPBs at closely located stations, for example, Kototabang (0.2°S, 100.3°E) and Sanya (18.3°N, 109.6°E), indicating that the decorrelation distance of EPB generation is small (hundreds of kilometers) in longitude. In contrast, after the initial generation of EPBs at one longitude, they can drift zonally more than 2000 km and extend from the magnetic equator to middle latitudes of 40° or higher under some conditions. These features make it difficult to identify the possible seeding sources for the EPBs and to accurately predict their occurrence, especially when the onset locations of EPBs are far outside the observation sector. This paper presents a review on the current knowledge of EPBs and ionospheric scintillations in the East and Southeast Asia, including their generation mechanism and occurrence morphology, and discusses some unresolved issues related to their short-term forecasting, including (1) what factors control the generation of EPBs, its day-to-day variability and storm-time behavior, (2) what factors control the evolution and lifetime of EPBs, and (3) how to accurately determine ionospheric scintillation from EPB measurements. Special focus is given to the whole process of the EPB generation, development and disruption. The current observing capabilities, future new facilities and campaign observations in the East and Southeast Asia in helping to better understand the short-term variability of EPBs and ionospheric scintillations are outlined.
We used ionosonde and GPS receivers during March–April in 2004–2005 and 2011–2015 to investigate ... more We used ionosonde and GPS receivers during March–April in 2004–2005 and 2011–2015 to investigate the latitudinal variation of equatorial plasma bubble (EPB) occurrence rate in cases of strong and weak pre-reversal enhancement (PRE). The ionosonde at Chumphon in Thailand was used to estimate the PRE strength. Ten GPS receivers in Southeast Asia, ranging from magnetic latitude (ML) of 4.4°S to 21.6°S, were used to investigate the latitudinal variation of EPB occurrence rate. In the case of strong PRE, the EPB occurrence rates decrease from 38.9% to 34.9% at ML of 4.4°S–7.2°S. Continuously, the occurrence rate increases and reaches the peak (44%) at ML of 9.3°S; afterward, the occurrence rate rapidly decreases and reaches below 5% at ML of 21.6°S. In the case of weak PRE, the occurrence rate decreases from 21.8% at ML of 4.4°S, seems constant (15.3%–16%) at ML of 8.2°S–12.1°S, and reaches less than 5% at ML of 16.1°S. Generally, the EPB occurrence rate and its latitudinal extension in ...
The total solar eclipse on 9 March 2016 was a rare phenomenon that could be observed in 12 provin... more The total solar eclipse on 9 March 2016 was a rare phenomenon that could be observed in 12 provinces in Indonesia. The decline in solar radiation to the earth during a total solar eclipse affects the amount of electron content (TEC) in the ionosphere. The ionospheric dynamics during the eclipse above Indonesia have been studied using data from 40 GPS stations distributed throughout the archipelago. It was observed that TEC decrease occurred over Indonesia during the occurrence of the total eclipse. This TEC decrease did not instigate ionoshperic scintillation. Moreover, the relationship between eclipse magnitude and TEC decrease throughout three GPS stations was analyzed using PRN 24 and PRN 12 codes. Data analysis from each station reveals that the time required by the TEC to achieve maximum reduction since the initial contact of the eclipse is faster than the recovery time. The maximum TEC reduction came about several minutes after the maximum obscuration indicating that the recombination process was still ongoing even though the peak of the eclipse had happened. The magnitude of this decline is positively correlated with the geographical location of the stations and the relative satellite trajectory with respect to the total solar eclipse trajectory. The amount of TEC reduction is proportional to the magnitude of the eclipse which is directly related to the photoionization process. Because Indonesia is located in a low latitude magnetic equator region, the dynamics of the ionosphere above it is more complex due to the fountain effect. During the solar eclipse, the fountain effect declines disturbing the plasma transport from the magnetic equator to low latitude regions. 1 Introduction Atmospheric dynamics occur due to internal factors of the solar activities such as coronal mass ejection (CME), solar storms,
The ERICA study aims to find out signatures of the interplay between the magnetosphere-geomagneti... more The ERICA study aims to find out signatures of the interplay between the magnetosphere-geomagnetic field and the ionosphere that degrade trans-ionospheric signals such as those transmitted by GNSS satellites. The project activity focuses on the characterization of the ionospheric variability of the Equatorial Ionospheric Anomaly in the South East Asian region through the analysis of datasets collected with an ad hoc measurements campaign. The campaign has been conducted with ground-based instruments located in the footprints of the Equatorial Ionospheric Anomaly and Equatorial Ionospheric Trough. This paper presents some of the relevant results achieved by the project, in terms of ionospheric climatology and weather assessment over the interested area. In particular, the paper describes the average condition of the Equatorial Ionospheric Anomaly recorded during the entire campaign and provides interesting insights on relevant scintillation events.
A close link between the atmospheric Intertropical Convergence Zone (ITCZ) and ionospheric plasma... more A close link between the atmospheric Intertropical Convergence Zone (ITCZ) and ionospheric plasma bubble has been proposed since the last century. But this relationship has often appeared to be less than convincing due to the simultaneous roles played by several other factors in shaping the global distribution of ionospheric bubbles. From simultaneous collaborative radar multibeam steering measurements at Kototabang (0.2°S, 100.3°E) and Sanya (18.4°N, 109.6°E), conducted during September-October of 2012 and 2013, we find that the total numbers of nights with bubble (i.e., occurrence rates) at the two closely located longitudes (Kototabang and Sanya) are comparable. But interestingly, the total number of nights with locally generated bubble (i.e., generation rate) over Kototabang is clearly more than that over Sanya. Further analysis reveals that a more active ITCZ is situated around the longitude of Kototabang. We surmise that the enhanced ionospheric bubble generation at Kototabang longitude could be caused by a higher gravity wave activity associated with the more active ITCZ.
The penultimate sentence of the Measures section should have cited reference 41 instead of 39. In... more The penultimate sentence of the Measures section should have cited reference 41 instead of 39. In the Funding section, the name of the funder CIMVHR should be listed as "Canadian Institute for Military and Veteran Health Research (CIMVHR)".
The 2nd Equatorial Plasma Bubble (EPB) workshop, funded by the Institute of Geology and Geophysic... more The 2nd Equatorial Plasma Bubble (EPB) workshop, funded by the Institute of Geology and Geophysics, Chinese Academy of Sciences, and the National Natural Science Foundation of China, took place in Beijing, China during September 13-15, 2019. The EPB workshop belongs to a conference series that began in 2016 in Nagoya, Japan at the Institute for Space-Earth Environmental Research, Nagoya University, resulting in a special issue of Progress in Earth and Planetary Science that focused on EPBs. The main goal of the series is to organize in-depth discussion by scientists working on ionospheric irregularities, and solve the scientific challenges in EPB and ionospheric scintillation forecasting. The 2nd EPB workshop gathered almost 60 scientists from seven countries. A total of 20 invited and contributing papers focusing on ionospheric irregularities and scintillations were presented. Here we briefly comment on 10 papers included in this special issue.
Previous studies have proposed that both the thermospheric neutral wind and the equatorial electr... more Previous studies have proposed that both the thermospheric neutral wind and the equatorial electrojet (EEJ) near sunset play important roles in the pre‐reversal enhancement (PRE) mechanism. In this study, we have used observations made in the equatorial region of Southeast Asia during March–April and September–October in 2010–2013 to investigate influences of the eastward neutral wind and the EEJ on the PRE’s strength. Our analysis employs data collected by the Gravity Field and Steady‐State Ocean Circulation Explorer (GOCE) satellite to determine the zonal (east‐west direction) neutral wind at an altitude of ~250 km (bottomside F region) at longitudes of 90°–130°E in the dusk sector. Three ionosondes, at Chumphon (dip lat.: 3.0°N) in Thailand, at Bac Lieu (dip lat.: 1.7°N) in Vietnam, and at Cebu (dip lat.: 3.0°N) in Philippines, provided the data we have used to derive the PRE strength. Data from two magnetometers — at Phuket (dip lat.: 0.1°S) in Thailand and at Kototabang (dip lat.: 10.3°S) in Indonesia — were used to estimate the EEJ strength. Our study is focused particularly on days with magnetically quiet conditions. We have found that the eastward neutral wind and the EEJ are both closely correlated with the PRE; their cross‐correlation coefficients with it are, respectively, 0.42 and 0.47. Their relationship with each other is weaker: the cross‐correlation coefficient between the eastward neutral wind and the EEJ is just 0.26. Our findings suggest that both the eastward neutral wind and the EEJ near sunset are involved in the PRE mechanism. Based on the weak relationship between these two parameters, however, they appear to be significantly independent of each other. Thus, the wind and the EEJ are likely to be influencing the PRE magnitude independently, their effects balancing each other.
Ground-Based Augmentation System (GBAS) is a GNSS augmentation system that meets International Ci... more Ground-Based Augmentation System (GBAS) is a GNSS augmentation system that meets International Civil Aviation Organization (ICAO) requirements to support precision approach and landing. GBAS is based on the local differential GNSS technique with reference stations located around the airport to provide necessary integrity and accuracy. The performance of the GBAS system can be affected by the gradient in the ionospheric delay between the aircraft and the reference stations. A nominal ionospheric gradient, which is bounded by a conservative error bound, is represented by a parameter σvig. σvig was commonly determined using station pair to GNSS Continuous Operating Reference Station (CORS) data. The station pair method is susceptible to doubling of receiver bias error and is not suitable with the CORS conditions in Indonesia. We propose a satellite pair method that is found to be more suitable for the CORS network over Indonesia which is centered in Java and Sumatra islands. The value ...
Observations of Ionosphere as a wireless channel using channel sounder method is needed to obtain... more Observations of Ionosphere as a wireless channel using channel sounder method is needed to obtain the channel parameters characteristic. The Sliding Correlator Channel Sounder is known as a popular technique with low complexity and relatively low cost. Similar to the sliding correlator, Software Define Radio (SDR) device is one of the popular inexpensive platforms for implementing the system into the real world. Implementation of the sliding correlator channel sounder technique in the SDR platform will increase the ionosphere channel measurement system's advantages as an effort to obtain the dynamic of ionospheric channel characteristics. However, to guarantee the designed system able to works according to the SDR device specifications and meet the system performance targets, the optimization should be done. This paper discusses the design of a sliding correlator channel sounder system to observe the characteristics of ionosphere channels using SDR with consideration to the limitation of the hardware specification and the system performance target based on the recommendation of ionospheric channel characteristics ITU-R F.1487. Simulation and over-the-air test from the design results show that the expected system performance can be met and realized in a real-world implementation.
We used ionosondes in Chumphon (CPN) (10.72°N, 99.37°E; Mag. Lat: 3°N), Thailand; Bac Lieu (BCL) ... more We used ionosondes in Chumphon (CPN) (10.72°N, 99.37°E; Mag. Lat: 3°N), Thailand; Bac Lieu (BCL) (9.30°N, 105.71°E; Mag. Lat: 1.5°N), Vietnam; and Cebu (CEB) (10.35°N, 123.91°E; Mag. Lat: 3.09°N), Philippines during equinox seasons from 2010 to 2016 to develop a forecast technique for equatorial spread F or plasma bubble generation. We considered that enhancement of vertical E ×B drift after sunset in the equatorial region, so-called pre-reversal enhancement (PRE), is a primary factor for plasma bubble generation. We then used a "PRE threshold" to determine ESF whether generates or not. We collected 264, 121, and 206 nights for CPN, BCL, and CEB ionosondes, respectively. We used change of h'f in time ( dh'f/dt) during 18-19 LT from three ionosonde sites as a proxy for the vertical drift. The threshold is simply defined with a average value of vertical drifts obtained from all stations, and the value is 24 m/s. We defined the PRE 24 m/s and PRE < 24 m/s for the E...
Equatorial plasma bubbles (EPB) adalah fenomena ketidakteraturan di lapisan ionosfer bumi akibat ... more Equatorial plasma bubbles (EPB) adalah fenomena ketidakteraturan di lapisan ionosfer bumi akibat perbedaan kerapatan elektron antara dua lapisan di dalamnya. Berdasarkan perbedaan kerapatan elektron, lapisan ionosfer terdiri dari lapisan D, lapisan E, dan lapisan F. Pada lapisan F, terjadi penipisan lapisan akibat adanya kenaikan bagian bawah lapisan dengan kerapatan elektron lebih kecil yang mendorong ke atas, ke lapisan dengan kerapatan elektron lebih besar melalui mekanisme ketakstabilan Rayleigh–Taylor. Fenomena tersebut dikenal dengan istilah plasma bubbles (gelembung plasma). Pembentukan gelembung plasma ini terjadi di sektor ekuator, sesaat setelah matahari tenggelam. Kajian tentang fenomena ini menarik karena EPB dapat menyebabkan perubahan kerapatan elektron secara cepat dan berpengaruh terhadap penjalaran sinyal gelombang radio yang melewati lapisan ionosfer baik berupa gangguan dalam amplitudo maupun fasenya, biasa dikenal sebagai sintilasi. Salah satu parameter yang menj...
Equatorial plasma bubbles (EPBs) can cause rapid fluctuations in amplitude and phase of radio sig... more Equatorial plasma bubbles (EPBs) can cause rapid fluctuations in amplitude and phase of radio signals traversing the ionosphere and in turn produce serious ionospheric scintillations and disrupt satellite-based communication links. Whereas numerous studies on the generation and evolution of EPBs have been performed, the prediction of EPB and ionospheric scintillation occurrences still remains unresolved. The generalized Rayleigh–Taylor (R–T) instability has been widely accepted as the physical mechanism responsible for the generation of EPBs. But how the factors, which seed the development of R–T instability and control the dynamics of EPBs and resultant ionospheric scintillations, change on a short-term basis are not clear. In the East and Southeast Asia, there exist significant differences in the generation rates of EPBs at closely located stations, for example, Kototabang (0.2°S, 100.3°E) and Sanya (18.3°N, 109.6°E), indicating that the decorrelation distance of EPB generation is small (hundreds of kilometers) in longitude. In contrast, after the initial generation of EPBs at one longitude, they can drift zonally more than 2000 km and extend from the magnetic equator to middle latitudes of 40° or higher under some conditions. These features make it difficult to identify the possible seeding sources for the EPBs and to accurately predict their occurrence, especially when the onset locations of EPBs are far outside the observation sector. This paper presents a review on the current knowledge of EPBs and ionospheric scintillations in the East and Southeast Asia, including their generation mechanism and occurrence morphology, and discusses some unresolved issues related to their short-term forecasting, including (1) what factors control the generation of EPBs, its day-to-day variability and storm-time behavior, (2) what factors control the evolution and lifetime of EPBs, and (3) how to accurately determine ionospheric scintillation from EPB measurements. Special focus is given to the whole process of the EPB generation, development and disruption. The current observing capabilities, future new facilities and campaign observations in the East and Southeast Asia in helping to better understand the short-term variability of EPBs and ionospheric scintillations are outlined.
We used ionosonde and GPS receivers during March–April in 2004–2005 and 2011–2015 to investigate ... more We used ionosonde and GPS receivers during March–April in 2004–2005 and 2011–2015 to investigate the latitudinal variation of equatorial plasma bubble (EPB) occurrence rate in cases of strong and weak pre-reversal enhancement (PRE). The ionosonde at Chumphon in Thailand was used to estimate the PRE strength. Ten GPS receivers in Southeast Asia, ranging from magnetic latitude (ML) of 4.4°S to 21.6°S, were used to investigate the latitudinal variation of EPB occurrence rate. In the case of strong PRE, the EPB occurrence rates decrease from 38.9% to 34.9% at ML of 4.4°S–7.2°S. Continuously, the occurrence rate increases and reaches the peak (44%) at ML of 9.3°S; afterward, the occurrence rate rapidly decreases and reaches below 5% at ML of 21.6°S. In the case of weak PRE, the occurrence rate decreases from 21.8% at ML of 4.4°S, seems constant (15.3%–16%) at ML of 8.2°S–12.1°S, and reaches less than 5% at ML of 16.1°S. Generally, the EPB occurrence rate and its latitudinal extension in ...
The total solar eclipse on 9 March 2016 was a rare phenomenon that could be observed in 12 provin... more The total solar eclipse on 9 March 2016 was a rare phenomenon that could be observed in 12 provinces in Indonesia. The decline in solar radiation to the earth during a total solar eclipse affects the amount of electron content (TEC) in the ionosphere. The ionospheric dynamics during the eclipse above Indonesia have been studied using data from 40 GPS stations distributed throughout the archipelago. It was observed that TEC decrease occurred over Indonesia during the occurrence of the total eclipse. This TEC decrease did not instigate ionoshperic scintillation. Moreover, the relationship between eclipse magnitude and TEC decrease throughout three GPS stations was analyzed using PRN 24 and PRN 12 codes. Data analysis from each station reveals that the time required by the TEC to achieve maximum reduction since the initial contact of the eclipse is faster than the recovery time. The maximum TEC reduction came about several minutes after the maximum obscuration indicating that the recombination process was still ongoing even though the peak of the eclipse had happened. The magnitude of this decline is positively correlated with the geographical location of the stations and the relative satellite trajectory with respect to the total solar eclipse trajectory. The amount of TEC reduction is proportional to the magnitude of the eclipse which is directly related to the photoionization process. Because Indonesia is located in a low latitude magnetic equator region, the dynamics of the ionosphere above it is more complex due to the fountain effect. During the solar eclipse, the fountain effect declines disturbing the plasma transport from the magnetic equator to low latitude regions. 1 Introduction Atmospheric dynamics occur due to internal factors of the solar activities such as coronal mass ejection (CME), solar storms,
The ERICA study aims to find out signatures of the interplay between the magnetosphere-geomagneti... more The ERICA study aims to find out signatures of the interplay between the magnetosphere-geomagnetic field and the ionosphere that degrade trans-ionospheric signals such as those transmitted by GNSS satellites. The project activity focuses on the characterization of the ionospheric variability of the Equatorial Ionospheric Anomaly in the South East Asian region through the analysis of datasets collected with an ad hoc measurements campaign. The campaign has been conducted with ground-based instruments located in the footprints of the Equatorial Ionospheric Anomaly and Equatorial Ionospheric Trough. This paper presents some of the relevant results achieved by the project, in terms of ionospheric climatology and weather assessment over the interested area. In particular, the paper describes the average condition of the Equatorial Ionospheric Anomaly recorded during the entire campaign and provides interesting insights on relevant scintillation events.
A close link between the atmospheric Intertropical Convergence Zone (ITCZ) and ionospheric plasma... more A close link between the atmospheric Intertropical Convergence Zone (ITCZ) and ionospheric plasma bubble has been proposed since the last century. But this relationship has often appeared to be less than convincing due to the simultaneous roles played by several other factors in shaping the global distribution of ionospheric bubbles. From simultaneous collaborative radar multibeam steering measurements at Kototabang (0.2°S, 100.3°E) and Sanya (18.4°N, 109.6°E), conducted during September-October of 2012 and 2013, we find that the total numbers of nights with bubble (i.e., occurrence rates) at the two closely located longitudes (Kototabang and Sanya) are comparable. But interestingly, the total number of nights with locally generated bubble (i.e., generation rate) over Kototabang is clearly more than that over Sanya. Further analysis reveals that a more active ITCZ is situated around the longitude of Kototabang. We surmise that the enhanced ionospheric bubble generation at Kototabang longitude could be caused by a higher gravity wave activity associated with the more active ITCZ.
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Papers by Prayitno Abadi