3-D Ionospheric Plasma Bubble Model for Ground-Based Augmentation System

2015 ◽  
Vol 781 ◽  
pp. 102-105
Author(s):  
Sarawoot Rungraengwajiake ◽  
Pornchai Supnithi
Keyword(s):  
Ionospheric Plasma ◽  
Satellite System ◽  
Ionospheric Irregularity ◽  
Storm Events ◽  
Plasma Bubble ◽  
Low Latitude ◽  
Aircraft Navigation ◽  
Time Simulation ◽  
Latitude Region ◽  
Global Navigation Satellite

The ground-based augmentation system (GBAS) is now an important system for assisting the global navigation satellite system (GNSS) based aircraft navigation during landing phases. Since the ionospheric irregularity is one of the most serious problem in the high-precision GBAS, the impacts of ionospheric irregularities to GBAS in many countries need to be studied before actual installation and operation. However, most of previous studies are based on the rare ionospheric storm events observed in US in the mid-latitude region. For Thailand, which is located in equatorial and low-latitude region, the ionospheric irregularity known as plasma bubble is a common phenomenon after sunset, considered to have adverse impact to the integrity of GBAS operation. In this paper, we propose a simple 3-D ionospheric plasma bubble model for studying its impacts on GBAS operation in Thailand. The background electron density generated by the NeQuick2 model combined with the rectangular depletion are used in the near real-time simulation.

scholarly journals Low-latitude scintillation occurrences around the equatorial anomaly crest over Indonesia

2014 ◽  
Vol 32 (1) ◽  
pp. 7-17 ◽  
Author(s):  
P. Abadi ◽  
S. Saito ◽  
W. Srigutomo
Keyword(s):  
Satellite System ◽  
Ionospheric Scintillation ◽  
Plasma Bubble ◽  
Equatorial Anomaly ◽  
Low Latitude ◽  
Magnetic Latitude ◽  
Background Density ◽  
Latitude Region ◽  
Global Navigation Satellite ◽  
First Time

Abstract. We investigated low-latitude ionospheric scintillation in Indonesia using two GPS receivers installed at Bandung (107.6° E, 6.9° S; magnetic latitude 17.5° S) and Pontianak (109.3° E, 0.02° S; magnetic latitude 8.9° S). This study aimed to characterise climatological and directional ionospheric scintillation occurrences, which are useful not only for the physics of ionospheric irregularities but also for practical use in GNSS (global navigation satellite system)-based navigation. We used the deployed instrument's amplitude scintillation (S4 index) data from 2009, 2010, and 2011; the yearly SSN (sunspot-smoothed numbers) were 3.1, 16.5, and 55.9, respectively. In summary, (1) scintillation occurrences in the post-sunset period (18:00–01:00 LT) during equinox months (plasma bubble season) at the two sites can be ascribed to the plasma bubble; (2) using directional analyses of the two sites, we found that the distribution of scintillation occurrences is generally concentrated between the two sites, indicating the average location of the EIA (equatorial ionisation anomaly) crest; (3) scintillation occurrence enhancements for the two sites in field-aligned directions are herein reported for the first time by ground-based observation in a low-latitude region; (4) distribution of scintillation occurrences at Pontianak are concentrated in the southern sky, especially in the southwest direction, which is very likely associated with the plasma bubble tilted westward with increasing latitude; and (5) scintillation occurrence in the post-midnight period in the non-plasma-bubble season is the most intriguing variable occurring between the two sites (i.e. post-midnight scintillations are observed more at Bandung than Pontianak). Most of the post-midnight scintillations observed at Bandung are concentrated in the northern sky, with low elevation angles. This might be due to the amplitude of irregularities in certain directions, which may be effectively enhanced by background density enhancement by the EIA and because satellite–receiver paths are longer in the EIA crest region and in a field-aligned direction.

The characteristics of transforming coordinates from the geocentric system WGS-84 for the Mercator projection under low latitudes conditions

2018 ◽  
Vol 940 (10) ◽  
pp. 2-6
Author(s):  
J.A. Younes ◽  
M.G. Mustafin
Keyword(s):  
Coordinate System ◽  
Satellite System ◽  
Programming Algorithm ◽  
Low Latitude ◽  
Model Calculations ◽  
Mercator Projection ◽  
Low Latitudes ◽  
Rectangular Coordinates ◽  
Global Navigation Satellite ◽  
Coordination Methods

The issue of calculating the plane rectangular coordinates using the data obtained by the satellite observations during the creation of the geodetic networks is discussed in the article. The peculiarity of these works is in conversion of the coordinates into the Mercator projection, while the plane coordinate system on the base of Gauss-Kruger projection is used in Russia. When using the technology of global navigation satellite system, this task is relevant for any point (area) of the Earth due to a fundamentally different approach in determining the coordinates. The fact is that satellite determinations are much more precise than the ground coordination methods (triangulation and others). In addition, the conversion to the zonal coordinate system is associated with errors; the value at present can prove to be completely critical. The expediency of using the Mercator projection in the topographic and geodetic works production at low latitudes is shown numerically on the basis of model calculations. To convert the coordinates from the geocentric system with the Mercator projection, a programming algorithm which is widely used in Russia was chosen. For its application under low-latitude conditions, the modification of known formulas to be used in Saudi Arabia is implemented.

scholarly journals Improving DGNSS Performance through the Use of Network RTK Corrections

2021 ◽  
Vol 13 (9) ◽  
pp. 1621
Author(s):  
Duojie Weng ◽  
Shengyue Ji ◽  
Yangwei Lu ◽  
Wu Chen ◽  
Zhihua Li
Keyword(s):  
Carrier Phase ◽  
Local Area ◽  
Satellite System ◽  
High Accuracy ◽  
Single Frequency ◽  
Baseline Length ◽  
Low Latitude ◽  
Phase Measurements ◽  
Network Rtk ◽  
Global Navigation Satellite

The differential global navigation satellite system (DGNSS) is an enhancement system that is widely used to improve the accuracy of single-frequency receivers. However, distance-dependent errors are not considered in conventional DGNSS, and DGNSS accuracy decreases when baseline length increases. In network real-time kinematic (RTK) positioning, distance-dependent errors are accurately modelled to enable ambiguity resolution on the user side, and standard Radio Technical Commission for Maritime Services (RTCM) formats have also been developed to describe the spatial characteristics of distance-dependent errors. However, the network RTK service was mainly developed for carrier-phase measurements on professional user receivers. The purpose of this study was to modify the local-area DGNSS through the use of network RTK corrections. Distance-dependent errors can be reduced, and accuracy for a longer baseline length can be improved. The results in the low-latitude areas showed that the accuracy of the modified DGNSS could be improved by more than 50% for a 17.9 km baseline during solar active years. The method in this paper extends the use of available network RTK corrections with high accuracy to normal local-area DGNSS applications.

Research Progresses of Ionospheric Plasma Irregularities from the Ground–Based Airglow Network in China

2021 ◽  
Author(s):  
Jiyao Xu ◽  
Wei Yuan ◽  
Kun Wu ◽  
Longchang Sun
Keyword(s):  
Ionospheric Plasma ◽  
Ionospheric Disturbance ◽  
Geomagnetic Latitude ◽  
Extreme Weather Events ◽  
Plasma Bubble ◽  
Low Latitude ◽  
Plasma Irregularities ◽  
Middle Latitudes ◽  
Weather Events ◽  
New Phenomena

<p>China, from north to south, spans from the middle latitudes to the low latitude both in geographic latitude and geomagnetic latitude. And China has a variety of topography environment, which including high lands, plains, seas, and long coasts. To better understand topographic and latitudinal effects on the mesosphere and thermosphere and features of ionospheric plasma irregularities at various latitudes in China, we have established a ground-based airglow network in China gradually since 2010, which consists of 16 stations. This network almost cover China, which focuses on two airglow layers: the OI (~250 km) and OH (~87 km) airglow layers. The observations from OI airglow layers provide convenience to systematically investigate the morphologic feature and evolution of ionospheric plasma irregularities over China. Based on the airglow network observations, we mainly report some important research results of ionospheric plasma irregularities in recent years. These findings include (1) statistical characteristic of equatorial plasma bubble (EPB) over China, (2) the influences of severe extreme weather events on the ionosphere, (3) interaction between medium-scale traveling ionospheric disturbance (MSTIDs) and ionospheric irregularity, and (4) some new phenomena of ionospheric irregularities.</p>

scholarly journals Investigation of the Occurrence of Nighttime Topside Ionospheric Irregularities in Low-Latitude and Equatorial Regions Using CYGNSS Satellites

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 708 ◽  
Author(s):  
Liang Huang ◽  
Yi Liu ◽  
Qiong Tang ◽  
Guanyi Chen ◽  
Zhuangkai Wang ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Global Analysis ◽  
Satellite System ◽  
Ionospheric Irregularities ◽  
Wave Number ◽  
Significant Finding ◽  
Low Latitude ◽  
Zonal Wave Number ◽  
Global Navigation Satellite ◽  
Maximum Occurrence

By using multi-satellite observations of the L1 signal-to-noise ratio (SNR) from the Cyclone Global Navigation Satellite System (CYGNSS) taken in 2017, we present the occurrence of nighttime topside ionospheric irregularities in low-latitude and equatorial regions. The most significant finding of this study is the existence of longitudinal structures with a wavenumber 4 pattern in the topside irregularities. This suggests that lower atmospheric waves, especially a daytime diurnal eastward-propagating zonal wave number-3 nonmigrating tide (DE3), might play an important role in the generation of topside plasma bubbles during the low solar minimum. Observations of scintillation events indicate that the maximum occurrence of nighttime topside ionospheric irregularities occurs on the magnetic equator during the equinoxes. The current work, which could be regarded as an important update of the previous investigations, would be readily for the further global analysis of the topside ionospheric irregularities.

scholarly journals Signature of ionospheric irregularities under different geophysical conditions on SBAS performance in the western African low-latitude region

2017 ◽  
Vol 35 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Oladipo Emmanuel Abe ◽  
Xurxo Otero Villamide ◽  
Claudia Paparini ◽  
Rodrigue Herbert Ngaya ◽  
Sandro M. Radicella ◽  
...  
Keyword(s):  
Satellite System ◽  
Rate Of Change ◽  
Ionospheric Irregularities ◽  
Civil Aviation ◽  
Single Frequency ◽  
African Region ◽  
Low Latitude ◽  
Plasma Irregularities ◽  
Feasibility Assessment ◽  
Latitude Region

Abstract. Rate of change of TEC (ROT) and its index (ROTI) are considered a good proxy to characterize the occurrence of ionospheric plasma irregularities like those observed after sunset at low latitudes. SBASs (satellite-based augmentation systems) are civil aviation systems that provide wide-area or regional improvement to single-frequency satellite navigation using GNSS (Global Navigation Satellite System) constellations. Plasma irregularities in the path of the GNSS signal after sunset cause severe phase fluctuations and loss of locks of the signals in GNSS receiver at low-latitude regions. ROTI is used in this paper to characterize plasma density ionospheric irregularities in central–western Africa under nominal and disturbed conditions and identified some days of irregularity inhibition. A specific low-latitude algorithm is used to emulate potential possible SBAS message using real GNSS data in the western African low-latitude region. The performance of a possible SBAS operation in the region under different ionospheric conditions is analysed. These conditions include effects of geomagnetic disturbed periods when SBAS performance appears to be enhanced due to ionospheric irregularity inhibition. The results of this paper could contribute to a feasibility assessment of a European Geostationary Navigation Overlay System-based SBAS in the sub-Saharan African region.

scholarly journals Correlation between Ionospheric TEC and the DCB Stability of GNSS Receivers from 2014 to 2016

2019 ◽  
Vol 11 (22) ◽  
pp. 2657 ◽  
Author(s):  
Choi ◽  
Sohn ◽  
Lee
Keyword(s):  
Estimation Method ◽  
Satellite System ◽  
Electron Content ◽  
Strong Positive Correlation ◽  
Low Latitude ◽  
Total Electron ◽  
Gnss Receiver ◽  
Gnss Receivers ◽  
Global Navigation Satellite ◽  
The Relationship

The Global Navigation Satellite System (GNSS) differential code biases (DCBs) are a major obstacle in estimating the ionospheric total electron content (TEC). The DCBs of the GNSS receiver (rDCBs) are affected by various factors such as data quality, estimation method, receiver type, hardware temperature, and antenna characteristics. This study investigates the relationship between TEC and rDCB, and TEC and rDCB stability during a three-year period from 2014 to 2016. Linear correlations between pairs of variables, measured with Pearson’s coefficient (), are considered. It is shown that the correlation between TEC and rDCB is the smallest in low-latitude regions. The mid-latitude regions exhibit the maximum value of. In contrast, the correlation between TEC and rDCB root mean square (RMS, stability) was greater in low-latitude regions. A strong positive correlation (R≥0.90) on average between TEC and rDCB RMS was also revealed at two additional GNSS stations in low-latitude regions, where the correlation shows clear latitudinal dependency. We found that the correlation between TEC and rDCB stability is still very strong even after replacing a GNSS receiver.

scholarly journals Study on Seasonal Variations of Plasma Bubble Occurrence over Hong Kong Area Using GNSS Observations

2020 ◽  
Vol 12 (15) ◽  
pp. 2423 ◽  
Author(s):  
Long Tang ◽  
Wu Chen ◽  
Osei-Poku Louis ◽  
Mingli Chen
Keyword(s):  
Hong Kong ◽  
Seasonal Variations ◽  
Satellite System ◽  
Summer Solstice ◽  
Instability Mechanism ◽  
Plasma Bubble ◽  
Winter Solstice ◽  
Spring Equinox ◽  
Gnss Network ◽  
Global Navigation Satellite

In this study, the characteristics and causes of the seasonal variations in plasma bubble occurrence over the Hong Kong area were investigated using the local Global Navigation Satellite System (GNSS) network. Generally, the occurrences of plasma bubbles were larger in the two equinoxes than in the two solstices. Furthermore, two seasonal asymmetries in plasma bubble occurrence were observed: plasma bubble activity was more frequent in the spring equinox than in the autumn equinox (equinoctial asymmetry), and more frequent in the summer solstice than in the winter solstice (solstitial asymmetry). The equinoctial asymmetry could be explained using the Rayleigh–Taylor (R–T) instability mechanism, due to larger R–T growth rates in the spring equinox than in the autumn equinox. However, the R–T growth rate was smaller in the summer solstice than in the winter solstice, suggesting the R–T instability mechanism was inapplicable to the solstitial asymmetry. Our results showed there were more zonally propagating atmospheric gravity waves (GWs) induced by thunderstorm events over the Hong Kong area in the summer solstice than the winter solstice. So, the solstitial asymmetry could be attributed to the seeding mechanism of thunderstorm-driven atmospheric GWs.

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