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Investigation of low latitude scintillations in Brazil within the cigala project
Author(s)
Language
English
Obiettivo Specifico
1.7. Osservazioni di alta e media atmosfera
3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
Status
Published
JCR Journal
N/A or not JCR
Peer review journal
Yes
Issue/vol(year)
/ WWP 326 (2011)
Publisher
ESA (European Space Agency)
Issued date
September 2011
Subjects
Keywords
Abstract
Ionospheric scintillations are fluctuations in the phase and amplitude of the signals from GNSS satellites occurring when they cross regions of electron density irregularities in the ionosphere. Such disturbances can cause serious degradation on GNSS system performance, including integrity, accuracy and availability. The two indices internationally adopted to characterize ionospheric scintillations are: the amplitude scintillation index, S4, which is the standard deviation of the received power normalized by its mean value, and the phase scintillation index, σΦ, which is the standard deviation of the de-trended carrier phase. At low latitudes scintillations occur very frequently and can be intense. This is because the low latitudes show a characteristic feature of the plasma density, known as the equatorial anomaly, EA, for which a plasma density enhancement is produced and seen as crests on either side of the magnetic equator. It is a region in which the electron density is considerably high and inhomogeneous, producing ionospheric irregularities causing scintillations. The upcoming solar maximum, which is expected to reach its peak around May 2013, occurs at a time when our reliance on high-precision GNSS (such as GPS, GLONASS and the forthcoming GALILEO) has reached unprecedented proportions. Understanding and monitoring of scintillations are essential, so that warnings and forecast information can be made available to GNSS end users, either for global system or local augmentation network administrators in order to guarantee the necessary levels of accuracy, integrity and availability of high precision and/or safety-of-life applications. Especially when facing severe geospatial perturbations, receiver-level mitigations are also needed to minimize adverse effects on satellite signals tracking availability and accuracy. In this context, the challenge of the CIGALA (Concept for Ionospheric scintillation mitiGAtion for professional GNSS in Latin America) project, co-funded by the European GNSS Agency (GSA) through the European 7th Framework Program, is to understand the causes of ionospheric disturbances and model their effects in order to develop novel counter-measure techniques to be implemented in professional multi-frequency GNSS receivers. This paper describes the scientific advancements made within the project to understand and characterize ionospheric scintillation in Brazil by means of historical and new datasets.
References
Aarons, J. (1982). Global morphology of ionospheric scintillations. Proc. IEEE. 70(4), 360-378.
2. Aquino, M., Monico, J.F.G., Dodson, A.H., Marques, H., De Franceschi, G., Alfonsi, L., Romano, V. & Andreotti, M. (2009). Improving the GNSS Positioning Stochastic Model in the Presence of IS. Journal of Geodesy. 83(10), 953-966.
3. Aquino, M., Veettil, S., Elmas, Z., Forte, B., Alfonsi, L., Wernik, A. & Monico, J.F.G. (2011). First version of prediction model for scintillation occurrence and receiver tracking performance for realistic conditions of the Latin American low latitudes and during high solar activity. CIGALA Project Deliverable D2.3-01-WP200.
4. Alfonsi, L., Spogli, L., De Franceschi, G., Romano, V., Aquino, M., Dodson, A. & Mitchell, C.N. (2011). Bipolar climatology of GPS ionospheric scintillation at solar minimum. Radio Sci. 46, RS0D05, doi:10.1029/2010RS004571.
5. Basu, Su., Basu, Sa. & Khan, B.K. (1976). Model of equatorial scintillation from in-situ measurements. Radio Sci. 11(10), 821-832.
6. Coïsson, P., Nava, B., Radicella, S.M., Oladipo, O.A., Adeniyi, J.O., Gopi Krishna, S., Rama Rao, P.V.S. & Ravindran, S. (2008). NeQuick bottomside analysis at low latitudes. J. Atmos. Solar-Terr. Phys. 70(15), 1911-1918.
7. Conker, R.S., El Arini, M.B., Hegarty, C.J. & Hsiao, T. (2003). Modeling the effects of ionospheric scintillation on GPS/SBAS availability. Radio Sci. 38(1), doi:10.1029/ 2000RS002604.
8. Hanson, W.B., Heelis, R.A., Power, R.A., Lippincott, C.R., Zuccaro, D.R., Holt, B.J., Harmon, L.H. & Sanatani, S. (1981). The retarding potential analyzer for Dynamics Explorer-B. Space Sci. Instrum. 5, 503-510.
9. Humphreys, T.E., Psiaki, M.L. & Kintner, P.M. Jr. (2010). Modeling the effects of ionospheric scintillation on GPS carrier phase tracking. IEEE Transactions on Aerospace and Electronic Systems. 46(4), 1624-1637.
10. Rino, C.L. (1979). A power law phase screen model for ionospheric scintillation, I. Weak scattering. Radio Sci. 14, 1135-1145.
11. Secan, J.A., Bussey, R.M., Fremouw, E.J. & Basu, Sa. (1995). An improved model of equatorial scintillation. Radio Sci. 30(3), 607-617.
12. Septentrio (2010). Septentrio announces PolaRxS, A State-of-the-Art Ultra Low Noise GNSS Receiver for Ionospheric Scintillation Monitoring. Online at http://www.septentrio.com/news/ (as of 20 September 2010).
13. Spogli, L., Alfonsi, L., De Franceschi, G., Romano, V., Aquino, M.H.O. & Dodson, A. (2009). Climatology of GPS ionospheric scintillations over high and mid-latitude European regions. Ann. Geophys. 27, 3429-3437.
14. Wernik, A.W. & Liu, C.H. (1974). Ionospheric irregularities causing scintillations of GHz frequency radio signals. J. Atmos. Terr. Phys. 36, 871-879.
15. Wernik, A.W., Alfonsi, L., Materassi, M. (2007). Scintillation modelling using in-situ data. Radio Sci. 42(1), RS1002, doi:10.1029/2006RS003512.
2. Aquino, M., Monico, J.F.G., Dodson, A.H., Marques, H., De Franceschi, G., Alfonsi, L., Romano, V. & Andreotti, M. (2009). Improving the GNSS Positioning Stochastic Model in the Presence of IS. Journal of Geodesy. 83(10), 953-966.
3. Aquino, M., Veettil, S., Elmas, Z., Forte, B., Alfonsi, L., Wernik, A. & Monico, J.F.G. (2011). First version of prediction model for scintillation occurrence and receiver tracking performance for realistic conditions of the Latin American low latitudes and during high solar activity. CIGALA Project Deliverable D2.3-01-WP200.
4. Alfonsi, L., Spogli, L., De Franceschi, G., Romano, V., Aquino, M., Dodson, A. & Mitchell, C.N. (2011). Bipolar climatology of GPS ionospheric scintillation at solar minimum. Radio Sci. 46, RS0D05, doi:10.1029/2010RS004571.
5. Basu, Su., Basu, Sa. & Khan, B.K. (1976). Model of equatorial scintillation from in-situ measurements. Radio Sci. 11(10), 821-832.
6. Coïsson, P., Nava, B., Radicella, S.M., Oladipo, O.A., Adeniyi, J.O., Gopi Krishna, S., Rama Rao, P.V.S. & Ravindran, S. (2008). NeQuick bottomside analysis at low latitudes. J. Atmos. Solar-Terr. Phys. 70(15), 1911-1918.
7. Conker, R.S., El Arini, M.B., Hegarty, C.J. & Hsiao, T. (2003). Modeling the effects of ionospheric scintillation on GPS/SBAS availability. Radio Sci. 38(1), doi:10.1029/ 2000RS002604.
8. Hanson, W.B., Heelis, R.A., Power, R.A., Lippincott, C.R., Zuccaro, D.R., Holt, B.J., Harmon, L.H. & Sanatani, S. (1981). The retarding potential analyzer for Dynamics Explorer-B. Space Sci. Instrum. 5, 503-510.
9. Humphreys, T.E., Psiaki, M.L. & Kintner, P.M. Jr. (2010). Modeling the effects of ionospheric scintillation on GPS carrier phase tracking. IEEE Transactions on Aerospace and Electronic Systems. 46(4), 1624-1637.
10. Rino, C.L. (1979). A power law phase screen model for ionospheric scintillation, I. Weak scattering. Radio Sci. 14, 1135-1145.
11. Secan, J.A., Bussey, R.M., Fremouw, E.J. & Basu, Sa. (1995). An improved model of equatorial scintillation. Radio Sci. 30(3), 607-617.
12. Septentrio (2010). Septentrio announces PolaRxS, A State-of-the-Art Ultra Low Noise GNSS Receiver for Ionospheric Scintillation Monitoring. Online at http://www.septentrio.com/news/ (as of 20 September 2010).
13. Spogli, L., Alfonsi, L., De Franceschi, G., Romano, V., Aquino, M.H.O. & Dodson, A. (2009). Climatology of GPS ionospheric scintillations over high and mid-latitude European regions. Ann. Geophys. 27, 3429-3437.
14. Wernik, A.W. & Liu, C.H. (1974). Ionospheric irregularities causing scintillations of GHz frequency radio signals. J. Atmos. Terr. Phys. 36, 871-879.
15. Wernik, A.W., Alfonsi, L., Materassi, M. (2007). Scintillation modelling using in-situ data. Radio Sci. 42(1), RS1002, doi:10.1029/2006RS003512.
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