Ionospheric scintillation and TEC studies over Brazil using GNSS: progresses and problems

E. R. de Paula1, M. T.H.A. Muella2, J.F.G. Monico3, P. M. de Siqueira1, A.O. Moraes4, R.Y.C.

Cueva1,L. F. C. de Rezende1, A.C. Neto1, A. P. S. Dutra1 and P. C. P. dos Santos1

1- INPE Aeronomy Division S. J. dos Campos São Paulo Brazil eurico@dae.inpe.br

2- UNIVAP São José dos Campos São Paulo, Brazil3-UNESP Presidente Prudente São Paulo Brazil

4- IAE Instituto de Aeronáutica e Espaço S.J. dos Campos São Paulo Brazil

OUTLINE• GNSS networks at Brazil: SCINTMON(EURICO),

LISN(EURICO/CESAR), CIGALA (Galera), RBMC/IBGE(Sonia Costa), SIPEG (Ícaro Vitorello) and IGS

• S4 and TEC scientific studies• Scintillation effects over GNSS• Network operational problems• S4 calculations from different systems – each system has it own

methodology to calculate S4 -> problem• Different models for absolute TEC calculation• Preliminar results from a campaign to study the behavior of

different GNSS receivers during scintillation• Initiatives for scintillation prediction

MAGNETIC EQUATOR

GPS receivers: (SCINTEC-CASCADE)INPE

Receivers single L1 frequency

Belem-PABelo Horizonte-MGBoa Vista-RRBrasilia-DFCachoeira Paulista-SPCuiabá-MTManaus-AMNatal-RNPato Branco-PRPresidente Prudente-SPSanta Maria-RSSão João do Cariri-PBSão José dos Campos-SPSão Luís-MATefé-AM

- Sample Rate: 50Hz - GEC-PLESSEY Card- INPE/CORNELL- Zonal Velocity

capability - Amplitude

Scintillation (S4)

LISN / NSF Alta Floresta-MTBelo Horizonte-MGBoa Vista-RRBrasília-DFCachoeira Paulista-SPCuiabá-MTDourados-MSIlhéus-BAImperatriz-MANatal-RNParintins-AMPato Branco - PRPetrolina-PEPorto Velho-RORio Branco-ACSanta Maria-RSSão Luís-MASão José dos Campos-SPSão Gabriel da Cachoeira-AMSantarém-PATefé-AM

GPS stations in BRAZIL: (BLISN)

CURRENT STATIONS - LISN

MAGNETIC EQUATOR

- Sample rate: 50 Hz- INPE/BC(NSF)- TEC and S4- Novatel 4004 B

(19) e Ashtech (2)

RBMC/IBGE GNSS NETWORK- Dual Frequency

receivers -> TEC- Contact Sonia Costa:

sonia.alves@ibge.gov.br

Stations in Operation and Predicted for 2012

GNSS POSITIONING INTEGRATED SYSTEM FOR GEODYNAMIC STUDIES– SIPEG (Dr. Ícaro Vitorello)

Blue 09- PermanentYellow 22- TemporarilyRed 19- Predicted for 2012Light blue 08-Permanent IBGE;04 with tide gauges03 with PTH sensor

Dual Frequency 105 Trimble NET R8 -> TEC

Contact Ícaro Vitorello: icaro@dge.inpe.br

S4 AND TEC SCIENTIFIC STUDIES• Irregularity zonal velocity using cross-correlation methology

with spaced GNSS receivers (Márcio Muella)• Irregularity (S4) and TEC morphology due to solar flux, local

time, season, location• TEC behavior during magnetic storms• Influence of MSTIDs and GWs on the irregularity generation• SSW (Sudden Stratospheric Warming) effects over scintillation

and TEC• TEC periodicities• Scintillation models (WAM, E. Costa/PUC, GIM( Yannick))

validation

IRREGULARITY (S4) AND TEC MORPHOLOGY DUE TO SOLAR FLUX, LOCAL TIME, SEASON, LOCATION

MAGNETIC STORMS: INHIBITED OR TRIGGER IONOSPHERIC SCINTILLATION

Example of a case of storm triggered scintillation.

Example of a case of storm inhibited scintillation.

Another lock loss

Long period

LOSS OF LOCK DUE TO SCINTILLATION

DGPS Loss of Signal in one petroleum drilling ship

• Boa tarde,

Gostaria de saber se é possível você me enviar algum dado referente a cintilação entre a noite do dia 19/09/2012 e a madrugada do dia 20/09/2012? Verificamos que tivemos uma perda de sinal de nossos sistemas DGPS e gostariamos dessa informação. Desde já agradeço o retordo

Oficial de Náutica - Jansen Bridge Skandi Salvador

  Tel.:   55 + 22 2105-8358 Mob.: 55 + 21 7123-8252 Sat :+55 21 870 764 885927 www.norskan.com.br

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DGPS Loss of Signal in one petroleum drilling ship-S4 from CIGALA Septentrio receiver on 09/19-20/2012

- Lack of working people at the station- Lack of training for these people- Lack of daily remote station monitoring- Lack of financial support for remore station maintenance: travels, local people, damaged equipment reposition- Lack of financial support to purchase more receivers- Old micros, receivers, antennas etc - Lack of support to people at remote stations- In many stations, mainly at Amazon region, there are frequent electrical power failures- Low rate/failing Internet connections shared with many links - Lightnings problems and lack of protection devices- Multipath problems (normaly growing trees around the antennas)- Firmware problems (LISN for instance almost 18 stations needs to be updated)- Clock steering problem (LISN)- Non access to some codes- Loss of data in the recording medias/servers- .- .

- CONSEQUENCE OF THESE PROBLEMS (FOR INSTANCE):

- LISN: only 03 out of 21 are operational at the moment at Brazil- SCINTEC/CASCADE: only 06 out of 20 are operational at the moment

GENERAL PROBLEMS RELATED WITH GNSS NETWORKS/DATA ANALYSIS ETC

NOAA (US-TEC)

Nagoya-TECMAP (suitable for dense networks)

MODION (UNESP)

Models for absolute TEC calculation in use at INPE

UNB

GI - Model

DIFFERENT GPS RECEIVERS CAMPAIGN TO CHECK PERFORMANCE DURING SCINTILLATION (SEPTENTRIO, NOVATEL 4004B AND GPS STATION 6, ASTRA AND GEC-PLESSEY)

DIFFERENT GPS RECEIVERS CAMPAIGN TO CHECK PERFORMANCE DURING SCINTILLATION (STANFORD SYSTEM – JUST ARRIVED)

Prediction of ionospheric scintillation

(L.F. C. de Rezende, 2009, Master Dissertation )- Ionospheric scintillation prediction is also been developed at INPE using vertical plasma drift from digisonde data

Thanks for the attention

• References relative to this work: eurico@dae.inpe.br

DGPS Loss of Signal in one petroleum drilling ship-S4 from CIGALA Septentrio receiver on 09/19/2012

Bad geometry Good geometry

Dilution of precision (DOP)

The expression “dilution of precision” (DOP) is used to name the effect of satellite geometry on the precision of navigation solution.

IONOSPHERIC SCINTILLATION EFFECTS OVER GPS SIGNAL

Measured decorrelation times

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fast scintillation (small 0) are associated with high S4 (Carrano and Groves, 2010)

shows a histogram describing the overall distribution of the measured decorrelation times. The histogram was computed for the S4 intervals described above, and for 0 intervals that were 0.1 seconds wide. An important feature of Figure 7 is that most of the fast scintillation cases (small 0) are associated with strong amplitude scintillation, i.e., high S4. When S4 is greater than 0.7, the decorrelation time is generally less than 0.3 seconds.

PROBLEMAS LOCAISNa região amazônica:

Energia elétrica de baixa qualidade com muitas oscilações. Nobreak e baterias são de extremas necessidades;Internet via radio de baixa velocidade (menos de 500 Kbps) compartilhada com todo o campus;Falta de dispositivo para proteção contra descargas atmosféricas, pois esta região tem registrado vários problemas com a falta destes dispositivos;A presença de arvores introduz ruídos nos sinais monitorados.Falta de pessoal com habilidades técnicas especificas. Nos demais locais, o principal problema é a falta de pessoas com habilidades técnicas especificas para atender a nossa demanda, e pratica de solicitação de favores não tem ajudado muito.Em algumas estações Lisn/Cascade precisamos trocar o computador e atualizar urgentemente o Firmware e scripts das estações remotas, mas não temos recursos para isto.Para as estações cascade, o principal problema está no software de monitoração, que por ter um código fechado nos limita. O equipamento já está obsoleto.

GENERAL PROBLEMS RELATED WITH GNSS NETWORKS/DATA ANALYSIS ETC

STATION MAX MIN MEA MED STDSão Luís 40.3 33.3 36.7 36.5 1.39Cuiabá 43.5 23.7 37.9 38.0 1.73São José dos Campos

48.1 19.1 38.3 38.7 2.89

Cumulative Distribution Function of amplitude for 6 Dec 2001

Ionospheric scintillation and TEC studies over Brazil using GNSS: progresses and problems

• Ionospheric scintillation and TEC studies over Brazil using GNSS: progresses and problems• • E. R. de Paula1, M. T.H.A. Muella2, J.F.G. Monico3, P. M. de Siqueira1, A.O. Moraes4, R.Y.C.

Cueva1,L. F. C. de Rezende1, A.C. Neto1, A. P. S. Dutra1 and P. C. P. dos Santos1

• • 1- INPE Aeronomy Division S. J. dos Campos São Paulo Brazil eurico@dae.inpe.br• 2- UNIVAP São José dos Campos São Paulo, Brazil• 3-UNESP Presidente Prudente São Paulo Brazil• 4- IAE Instituto de Aeronáutica e Espaço S.J. dos Campos São Paulo Brazil• • In this talk we present first the SCINTEC (INPE/Cornell GPS receiver network) amplitude

scintillation, the BLISN (Brazilian Low-Latitude Ionospheric Sensor Network that provides amplitude and phase scintillation and TEC) and the BCIGALA (Brazilian CIGALA) characteristics. Following we will present the progresses including scientific studies and applications using the S4 and TEC data measured at those GNSS receiver networks over Brazil, a region with a large magnetic declination and with a large occurrence of ionospheric irregularities. Some cases of ionospheric irregularity effects over GNSS positioning are going to be reported. We also will report problems with GNSS network maintenance mainly at remote sites including their transmission using external networks, with data manipulation (availability management, filtering and storaging), with scintillation indices from different receivers, with different models such as UNB(Canada), STELAB-INPE(Nagoya), USTEC (NOAA), MODION (UNESP), GI (UTFPR) to estimate absolute TEC, S4 and TEC in almost real time mapping (nowcasting) and some trials to forecast scintillation. Finally some preliminar results from a campaign at INPE to study the behavior of different GNSS receivers under scintillation environment will be presented.

The variability of amplitude scintillation patterns (Alison´s Phd)

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S4=0.9 Figure 4 shows four examples illustrating the variability in the decorrelation time computed from GPS L1 amplitude measurements made with very distinct 0 values: 0.94, 0.68, 0.43 and 0.18 seconds. This figure serves to exemplify the variability of amplitude scintillation patterns.The 0 value is defined as the time lag at which the autocorrelation function falls off by e-1 from its maximum (zero lag) value

SCINTILLATION AMPLITUDE DISTRIBUTIONS (ALISON’s Phd)

Influence of MSTIDs and GWs on the irregularity generation (Ricardo´s PhD)

Efeito do Ciclo Solar