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
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
GPS receivers:
(SCINTEC-CASCADE)
INPE
Receivers single
L1 frequency
MAGNETIC EQUATOR
Belem-PA
Belo Horizonte-MG
Boa Vista-RR
Brasilia-DF
Cachoeira Paulista-SP
Cuiabá-MT
Manaus-AM
Natal-RN
Pato Branco-PR
Presidente Prudente-SP
Santa Maria-RS
São João do Cariri-PB
São José dos Campos-SP
São Luís-MA
Tefé-AM
-
Sample Rate: 50Hz
GEC-PLESSEY Card
INPE/CORNELL
Zonal Velocity
capability
Amplitude
Scintillation (S4)
GPS stations in BRAZIL:
(BLISN)
CURRENT STATIONS - LISN
LISN / NSF
MAGNETIC EQUATOR
Alta Floresta-MT
Belo Horizonte-MG
Boa Vista-RR
Brasília-DF
Cachoeira Paulista-SP
Cuiabá-MT
Dourados-MS
Ilhéus-BA
Imperatriz-MA
Natal-RN
Parintins-AM
Pato Branco - PR
Petrolina-PE
Porto Velho-RO
Rio Branco-AC
Santa Maria-RS
São Luís-MA
São José dos Campos-SP
São Gabriel da Cachoeira-AM
Santarém-PA
Tefé-AM
-
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
GNSS POSITIONING INTEGRATED SYSTEM FOR
GEODYNAMIC STUDIES– SIPEG (Dr. Ícaro Vitorello)
Stations in Operation and Predicted for 2012
Blue
09- Permanent
Yellow 22- Temporarily
Red 19- Predicted for 2012
Light blue 08-Permanent
IBGE;
04 with tide gauges
03 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 .
LOSS OF LOCK DUE TO SCINTILLATION
Another lock loss
Long period
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
11
DGPS Loss of Signal in one petroleum drilling ship-S4 from
CIGALA Septentrio receiver on 09/19-20/2012
GENERAL PROBLEMS RELATED WITH GNSS NETWORKS/DATA ANALYSIS ETC
-
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
Models for absolute TEC calculation in use at INPE
Nagoya-TECMAP (suitable for dense networks)
UNB
NOAA (US-TEC)
MODION (UNESP)
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
IONOSPHERIC SCINTILLATION
EFFECTS OVER GPS SIGNAL
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.
Bad geometry
Good geometry
Measured decorrelation times
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.
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GENERAL PROBLEMS RELATED WITH GNSS NETWORKS/DATA ANALYSIS ETC
PROBLEMAS LOCAIS
Na 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
Cumulative Distribution Function of amplitude for 6 Dec 2001
STATION
MAX
MIN
MEA
MED
STD
São Luís
40.3
33.3
36.7
36.5
1.39
Cuiabá
43.5
23.7
37.9
38.0
1.73
São José dos
48.1
19.1
38.3
38.7
2.89
Campos
Ionospheric scintillation and TEC studies over Brazil using
GNSS: progresses and problems
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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)
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
26
SCINTILLATION AMPLITUDE DISTRIBUTIONS
(ALISON’s Phd)
Influence of MSTIDs and GWs on the irregularity generation (Ricardo´s PhD)
Efeito do Ciclo Solar