scholarly journals POSSÍVEL TID GERADO NA REGIÃO POLAR E OBSERVADO SOBRE ESTAÇÕES EQUATORIAIS E DE BAIXAS LATITUDES

2018 ◽  
Vol 4 ◽  
pp. 46-61
Author(s):  
Elio Pessoa Cazuza ◽  
Anderson Luiz Pinheiro De Oliveira ◽  
Hadassa Raquel Peixoto Jácome ◽  
Gilvan Luiz Borba ◽  
José Pedro Silva Junior ◽  
...  
Keyword(s):  
Large Scale ◽  
Ionospheric Disturbances ◽  
Radio Observatory ◽  
Travelling Ionospheric Disturbances

Os Distúrbios Ionosféricos Propagantes (TID’s - Travelling Ionospheric Disturbances) são irregularidades no plasma ionosférico que se propagam com velocidades da ordem de dezenas a poucas centenas de quilômetros por hora. Nesse trabalho, foram detectadas e caracterizadas perturbações do tipo LSTID’s (Large scale Travelling Ionospheric Disturbances), em baixas latitudes, durante intensas tempestades geomagnéticas e também a forma como se propagação. Utilizou-se registros ionosféricos obtidos a partir de digissondas do tipo CADI (Canadian Advanced Digital Ionosonde) localizada na cidade de Natal e do tipo DSP (Digisonde Portable Souder) localizadas nas cidades de Cachoeira Paulista, Ramey e Eglin. Os dados de sondagem de Ramey e Eglin foram disponibilizados pela Global Ionosphere Radio Observatory (GIRO). Para observar os efeitos de tempestades sobre a ionosfera polar, foram utilizadas imagens aurorais do polo Norte, obtidas pelo satélite POLAR, que mostraram a intensificação do eletrojato auroral pela injeção de partículas nas cúspides. O período analisado compreendeu os dias 06 e 07 de abril de 2000 e os índices utilizados para caracterizar a atividade magnética nesse período foram Dst, Kp, e AE, além da componente Bz do campo magnético interplanetário. A tempestade ocorrida no dia 6 de abril apresentou um Dstmin = - 288 nT. A partir de gráficos de isolinhas foram verificados comportamentos anômalos da ionosfera sobre as quatro cidades, caracterizando a propagação como sendo do tipo LSTID’s, gerados pela expansão do oval auroral nos polos.

scholarly journals A study of atmospheric gravity waves and travelling ionospheric disturbances at equatorial latitudes

1997 ◽  
Vol 15 (8) ◽  
pp. 1048-1056 ◽  
Author(s):  
R. L. Balthazor ◽  
R. J. Moffett
Keyword(s):  
Gravity Waves ◽  
Large Scale ◽  
Ionospheric Disturbance ◽  
Magnetic Equator ◽  
Ionospheric Disturbances ◽  
Atmospheric Gravity Waves ◽  
Opposite Hemisphere ◽  
Travelling Ionospheric Disturbances ◽  
F Region ◽  
Atmospheric Gravity

Abstract. A global coupled thermosphere-ionosphere-plasmasphere model is used to simulate a family of large-scale imperfectly ducted atmospheric gravity waves (AGWs) and associated travelling ionospheric disturbances (TIDs) originating at conjugate magnetic latitudes in the north and south auroral zones and subsequently propagating meridionally to equatorial latitudes. A 'fast' dominant mode and two slower modes are identified. We find that, at the magnetic equator, all the clearly identified modes of AGW interfere constructively and pass through to the opposite hemisphere with unchanged velocity. At F-region altitudes the 'fast' AGW has the largest amplitude, and when northward propagating and southward propagating modes interfere at the equator, the TID (as parameterised by the fractional change in the electron density at the F2 peak) increases in magnitude at the equator. The amplitude of the TID at the magnetic equator is increased compared to mid-latitudes in both upper and lower F-regions with a larger increase in the upper F-region. The ionospheric disturbance at the equator persists in the upper F-region for about 1 hour and in the lower F-region for 2.5 hours after the AGWs first interfere, and it is suggested that this is due to enhancements of the TID by slower AGW modes arriving later at the magnetic equator. The complex effects of the interplays of the TIDs generated in the equatorial plasmasphere are analysed by examining neutral and ion winds predicted by the model, and are demonstrated to be consequences of the forcing of the plasmasphere along the magnetic field lines by the neutral air pressure wave.

The Observation of Large Scale Travelling Ionospheric Disturbances Based on GPS Network

2002 ◽  
Vol 45 (4) ◽  
pp. 469-475 ◽  
Author(s):  
Dong-He ZHANG ◽  
K. Igarashi ◽  
Zuo XIAO ◽  
Guan-Yi MA
Keyword(s):  
Large Scale ◽  
Ionospheric Disturbances ◽  
Travelling Ionospheric Disturbances ◽  
Gps Network

scholarly journals An overview of methodologies for real-time detection, characterisation and tracking of traveling ionospheric disturbances developed in the TechTIDE project

2020 ◽  
Vol 10 ◽  
pp. 42
Author(s):  
Anna Belehaki ◽  
Ioanna Tsagouri ◽  
David Altadill ◽  
Estefania Blanch ◽  
Claudia Borries ◽  
...  
Keyword(s):  
Real Time ◽  
Large Scale ◽  
Tracking System ◽  
Warning System ◽  
Satellite System ◽  
Ionospheric Disturbances ◽  
Time Activity ◽  
Travelling Ionospheric Disturbances ◽  
Additional Information ◽  
Global Navigation Satellite

The main objective of the TechTIDE project (warning and mitigation technologies for travelling ionospheric disturbances effects) is the development of an identification and tracking system for travelling ionospheric disturbances (TIDs) which will issue warnings of electron density perturbations over large world regions. The TechTIDE project has put in operation a real-time warning system that provides the results of complementary TID detection methodologies and many potential drivers to help users assess the risks and develop mitigation techniques tailored to their applications. The TechTIDE methodologies are able to detect in real time activity caused by both large-scale and medium-scale TIDs and characterize background conditions and external drivers, as an additional information required by the users to assess the criticality of the ongoing disturbances in real time. TechTIDE methodologies are based on the exploitation of data collected in real time from Digisondes, Global Navigation Satellite System (GNSS) receivers and Continuous Doppler Sounding System (CDSS) networks. The results are obtained and provided to users in real time. The paper presents the achievements of the project and discusses the challenges faced in the development of the final TechTIDE warning system.

scholarly journals Some characteristics of large-scale travelling ionospheric disturbances and a relationship between the F<sub>2</sub> layer height rises of these disturbances and equatorial pre-sunrise events

2010 ◽  
Vol 28 (7) ◽  
pp. 1419-1430 ◽  
Author(s):  
G. G. Bowman ◽  
I. K. Mortimer
Keyword(s):  
Large Scale ◽  
Statistical Significance ◽  
Ionospheric Disturbances ◽  
Layer Height ◽  
Early Literature ◽  
Travelling Ionospheric Disturbances ◽  
The Earth

Abstract. Initially some characteristics of large-scale travelling ionospheric disturbances (LS-TIDs) have been discussed briefly particularly as reported in the early literature. These discussions also involve the literature on the generation of LS-TIDs at times of geomagnetic bays. Secondly, the possibility that LS-TIDs may be responsible for the F2 layer equatorial pre-sunrise height rises is investigated. Tabulations at hourly intervals of h'F at Huancayo and Washington for a Rz max period (1957–1960) have been used to identify height rises. For a three-hour interval at Huancayo h'F levels equal to or greater than 40 km of medians are used to identify the pre-sunrise height rises. Also height rises at Washington, which occurred earlier than those at Huancayo, have been considered for evidence of travelling disturbances. For 40 events analysed using geomagnetic bays and Washington height rises, a few hours before they occur at Huancayo, indicate the statistical significance of an association with LS-TIDs. Similar results of statistical significance have been obtained using Washington events and bays on average 34 h before 46 Huancayo events. These delays ranged from 29 h to 38 h. The results indicate that bays which occur the day before are responsible for LS-TIDs which encircle the earth.

scholarly journals Properties and Generation of Large Scale Travelling Ionospheric Disturbances during 8 September 2017

2020 ◽  
Author(s):  
Claudia Borries ◽  
Arthur Amaral Ferreira ◽  
Chao Xiong ◽  
Renato Alves Borges ◽  
Jens Mielich ◽  
...  
Keyword(s):  
Large Scale ◽  
Satellite System ◽  
Auroral Oval ◽  
Ionospheric Disturbances ◽  
High Latitudes ◽  
Travelling Ionospheric Disturbances ◽  
Source Mechanisms ◽  
Magnetometer Data ◽  
Space Weather Event ◽  
Global Navigation Satellite

&lt;p&gt;Large Scale Travelling Ionospheric Disturbances (LSTIDs) are a frequent phenomenon during ionospheric storms, indicating strong electrodynamic processes in high latitudes. LSTIDs are signatures of Atmospheric Gravity Waves (AGW) observed in the changes of the electron density in the ionosphere. During ionospheric storms, large scale AGWs are often generated in the vicinity of the auroral region, where sudden strong heating processes take place.&lt;/p&gt;&lt;p&gt;Many LSTIDs are observed during the ionosphere storm during the September 2017 Space Weather event. In this presentation, the LSTID occurrence on 8&lt;sup&gt;th&lt;/sup&gt; September 2017 is analysed in more detail, based on a TID detection method using ground based Global Navigation Satellite System (GNSS) measurements. Fast LSTIDs are observed in midlatitudes between 0-3 UT and 13-16 UT. Slow LSTIDs are observed between 3-12 UT. A significant strong wave-like TEC perturbation occurred in high latitudes at noon, which vanished at around 50&amp;#176;N. A strong single LSTID in mid-latitudes generated in high latitudes around 18 UT. Consulting IMAGE magnetometer data, ionosonde measurements and Swarm field aligned current measurements, strong heating processes, the extension of the Auroral oval and unusual electrodynamic processes are discussed as source mechanisms for these LSTIDs.&lt;/p&gt;

scholarly journals Some aspects of large-scale travelling ionospheric disturbances which originate at conjugate locations in auroral zones, cross the equator and sometimes encircle the earth

2011 ◽  
Vol 29 (12) ◽  
pp. 2203-2210 ◽  
Author(s):  
G. G. Bowman ◽  
I. K. Mortimer
Keyword(s):  
Large Scale ◽  
Ionospheric Disturbances ◽  
Sunspot Maximum ◽  
Travelling Ionospheric Disturbances ◽  
The Earth ◽  
Propagation Paths ◽  
Maximum Interval

Abstract. The occurrence of large-scale travelling ionospheric disturbances (LS-TIDs) has been examined. Initially some literature on their generation is considered. Travel during daylight hours and also paths which involve propagation paths towards the poles are illustrated by a few examples from the literature. A daytime ionogram recording of an LS-TID is presented and discussed as are nighttime ionogram recordings for a poleward path of propagation. The tabulations of Moscow h'F recordings around midnight are examined for significant height increases which along with geomagnetic bays some hours earlier confirm the existence of LS-TIDs. A sunspot-maximum interval is involved. Some of the Moscow events were related to bays which occurred 32 h earlier thus indicating earth encirclements. Also additional encirclements are recorded by using superposed-epoch analyses for some other events.

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