GEOMAGNETIC STORMS EFFECTS ON THE IONOSPHERE AND … · M. RODRÍGUEZ-BOUZA(1), I....
1
CONFERENCIA DE LA PLATAFORMA EUROPEA DE LA ESTRATEGIA INTERNACIONAL DE NACIONES UNIDAS PARA LA REDUCCIÓN DE DESASTRES Madrid, 6-8 Octubre 2014 GEOMAGNETIC STORMS EFFECTS ON THE IONOSPHERE AND GNSS POSITIONING IN THE IBERIAN PENINSULA M. RODRÍGUEZ-BOUZA (1) , I. RODRÍGUEZ-BILBAO (1) , M. HERRAIZ (1)(2) , G. RODRÍGUEZ-CADEROT (1)(3) , B. MORENO-MONGE (1) AND S. M. RADICELLA (4) (1) Dpto. de Física de la Tierra, Astronomía y Astrofísica I, Facultad de Ciencias Físicas ,Universidad Complutense de Madrid (UCM) (2) Instituto de Geociencias ,UCM, CSIC, Madrid, Spain (3)Instituto de Matemática Interdisciplinar UCM, Madrid, Spain (4) Telecommunications/ICT Development Laboratory (T/ICT4D) Abdus Salam International Center for Theoretical Physics (ICTP) 1. Introduction This research studies the effects of two geomagnetic storms on the ionosphere over the Iberian Peninsula and on the GNSS positioning. The storms started on December 14, 2006, and on April 23, 2012, in periods with low and high solar activity, respectively. According to the criteria of González et al. (1994) both can be classified as intense since the minimum Dst values are far below -50nT (Fig. 1) Figure 1. Dst index. Left: for December 11-22, 2006. Right: for April 20-30, 2012. 2. Data and Methodology Total electron content (TEC) has been obtained by processing (Ciraolo, 2012) GPS/GLONASS observations taken at some GNSS stations (Fig. 2) belonging to IGS, UNAVCO, IGP and IGN networks. The observation periods were chosen to cover all phases of the geomagnetic storms, 12-20, 2006, and April 21-29, 2012. We have studied the ionospheric response to the geomagnetic storms through the relative deviation of the vertical TEC (vTEC) over the stations, vTECrel, given by : vTECrel = (vTEC-vTECmed)/(vTECmed) (1) Figure 2. Stations distribution. 3. Results Figure 3 and Figure 4. Ionospheric response and PPP error during the storms of Dec, 2006 (left) and April, 2012 (rigth). In both: (a) vTEC map over the Iberian Peninsula in a quiet day (left) and during the second positive phase of the storm (right). (Figure 3 at 12 UT and Figure 4 at 00 UT). (b) Latitudinal plot of vTECrel (%) for the 9-day period studied. (c) vTEC value over three stations. In blue the monthly mean value and in red the actual value for each epoch. (d) Variation of the estimated altitude of 4 stations in kinematic PPP mode. (a) (b) (c) (d) (b) (c) (d) Where vTECmed is the monthly mean value of vTEC in quiet days. The RINEX files have been also processed by using the online [3] Canadian Spatial Reference System - Precise Point Positioning (CSRS-PPP) software (Kouba and Heroux, 2001) in kinematic mode considering an elevation mask of 10º. Acknowledgments: This work is part of the research activities of the "Grupo de Estudios Ionosféricos y Técnicas de Posicionamiento Satelital (GNSS)" funded by UCM/CAM, the project AYA 2010-15501 and MAPFRE. In addition, I. Rodríguez Bilbao holds a PhD fellowship funded by the Basque Country Government. The authors are very grateful to L. Ciarolo and F. J Sánchez Dulcet for their valuable collaboration and want to thank IGS, IGN, IGP and UNAVCO for providing the GNSS data, and NRCan for the CSRS-PPP online service. References: Gonzalez, W.D., et al. , What is a Geomagnetic Storm?, Journal of Geophysical Research, 99 5771–5792, (1994). Ciraolo, L. Ionospheric Total Electron Content (TEC) from the Global Positioning System, Personal communication (2012). Kouba, J. , P. Héroux, Precise point positioning using IGS orbit and clock products, GPS Solutions, 5(2), pp. 12-28, (2001). 4. Conclusions Figure 3 (a) and Figure 4(a) show the vTEC during the strongest phase of each ionospheric storm caused by the magnetic perturbations. It can be clearly seen that the vTEC increases during both storms with respect to the quiet days, and especially over the southern part of the Peninsula. The difference is larger during the 2012 storm. December 2006 storm: two positive ionospheric storm phases are observed (Figure 3(b)); one in the initial phase of the geomagnetic storm and the other one in the recovery phase, both with an increase greater than 50%. Following these positive phases and coinciding with the main and the recovery phase of the geomagnetic storm, negative phases of the ionospheric storm occurred but they were not so intense. A latitudinal behavior is also observed (Figure 3 (c)) with the highest increase in lower latitudes. No PPP errors related to this ionospheric phenomenon were found (Figure 3 (d)). The large noise in the 2006 data does not allow a deeper analysis. April 2012 storm: we have observed a positive effect associated to its main phase but is only appreciated at the lower latitudes (Figure 4(b)). The recovery phases is characterized by a first long negative phase, followed by a positive phase that only appear in the lower latitudes and again a negative phase. These three phases had a variation of around 50%. At lower latitudes (up to 38º), sTEC depletions were observed during the 23 rd to 24 th night coinciding with the main phase of the geomagnetic storm (Figure 4 (c)). PPP errors of 20 to 30cm in altitude in some stations of lower latitude occur at the same time as sTEC depletion related irregularities (Figure 4 (d)). (a) (c) (a) (c) Storm of 24 April 2012 Storm of 15 December 2006
Transcript of GEOMAGNETIC STORMS EFFECTS ON THE IONOSPHERE AND … · M. RODRÍGUEZ-BOUZA(1), I....
CONFERENCIA DE LA PLATAFORMA EUROPEA DE LA ESTRATEGIA INTERNACIONAL DE NACIONES UNIDAS PARA LA REDUCCIÓN DE DESASTRES
Madrid, 6-8 Octubre 2014
GEOMAGNETIC STORMS EFFECTS ON THE IONOSPHERE AND GNSS POSITIONING IN THE IBERIAN PENINSULA
M. RODRÍGUEZ-BOUZA(1), I. RODRÍGUEZ-BILBAO(1), M. HERRAIZ(1)(2), G. RODRÍGUEZ-CADEROT(1)(3), B. MORENO-MONGE(1) AND S. M. RADICELLA(4)
(1) Dpto. de Física de la Tierra, Astronomía y Astrofísica I, Facultad de Ciencias Físicas ,Universidad Complutense de Madrid (UCM) (2) Instituto de Geociencias ,UCM, CSIC, Madrid, Spain (3)Instituto de Matemática Interdisciplinar UCM, Madrid, Spain
(4) Telecommunications/ICT Development Laboratory (T/ICT4D) Abdus Salam International Center for Theoretical Physics (ICTP)
1. Introduction
This research studies the effects of two geomagnetic storms on the ionosphere over the Iberian Peninsula and on the GNSS positioning. The storms started on December 14, 2006, and on April 23, 2012, in periods with low and high solar activity, respectively. According to the criteria of González et al. (1994) both can be classified as intense since the minimum Dst values are far below -50nT (Fig. 1)
Figure 1. Dst index. Left: for December 11-22, 2006. Right: for April 20-30, 2012.
2. Data and Methodology
Total electron content (TEC) has been obtained by processing (Ciraolo, 2012) GPS/GLONASS observations taken at some GNSS stations (Fig. 2) belonging to IGS, UNAVCO, IGP and IGN networks. The observation periods were chosen to cover all phases of the geomagnetic storms, 12-20, 2006, and April 21-29, 2012. We have studied the ionospheric response to the geomagnetic storms through the relative deviation of the vertical TEC (vTEC) over the stations, vTECrel, given by :
vTECrel = (vTEC-vTECmed)/(vTECmed) (1)
Figure 2. Stations distribution.
3. Results
Figure 3 and Figure 4. Ionospheric response and PPP error during the storms of Dec, 2006 (left) and April, 2012 (rigth).
In both:
(a) vTEC map over the Iberian Peninsula in a quiet day (left) and during the second positive phase of the storm (right). (Figure 3 at 12 UT and Figure 4 at 00 UT).
(b) Latitudinal plot of vTECrel (%) for the 9-day period studied.
(c) vTEC value over three stations. In blue the monthly mean value and in red the actual value for each epoch.
(d) Variation of the estimated altitude of 4 stations in kinematic PPP mode.
(a)
(b)
(c)
(d)
(b)
(c)
(d)
Where vTECmed is the monthly mean value of vTEC in quiet days.
The RINEX files have been also processed by using the online[3] Canadian Spatial Reference System - Precise Point Positioning (CSRS-PPP) software (Kouba and Heroux, 2001) in kinematic mode considering an elevation mask of 10º.
Acknowledgments: This work is part of the research activities of the "Grupo de Estudios Ionosféricos y Técnicas de Posicionamiento Satelital (GNSS)" funded by UCM/CAM, the project AYA 2010-15501 and MAPFRE. In addition, I. Rodríguez Bilbao holds a PhD fellowship funded by the Basque Country Government. The authors are very grateful to L. Ciarolo and F. J Sánchez Dulcet for their valuable collaboration and want to thank IGS, IGN, IGP and UNAVCO for providing the GNSS data, and NRCan for the CSRS-PPP online service.
References: Gonzalez, W.D., et al. , What is a Geomagnetic Storm?, Journal of Geophysical Research, 99 5771–5792, (1994). Ciraolo, L. Ionospheric Total Electron Content (TEC) from the Global Positioning System, Personal communication (2012). Kouba, J. , P. Héroux, Precise point positioning using IGS orbit and clock products, GPS Solutions, 5(2), pp. 12-28, (2001).
4. Conclusions Figure 3 (a) and Figure 4(a) show the vTEC during the strongest phase of each ionospheric storm caused by the magnetic perturbations. It can be clearly seen that the vTEC increases during both storms with respect to the quiet days, and especially over the southern part of the Peninsula. The difference is larger during the 2012 storm.
December 2006 storm: two positive ionospheric storm phases are observed (Figure 3(b)); one in the initial phase of the geomagnetic storm and the other one in the recovery phase, both with an increase greater than 50%. Following these positive phases and coinciding with the main and the recovery phase of the geomagnetic storm, negative phases of the ionospheric storm occurred but they were not so intense. A latitudinal behavior is also observed (Figure 3 (c)) with the highest increase in lower latitudes. No PPP errors related to this ionospheric phenomenon were found (Figure 3 (d)). The large noise in the 2006 data does not allow a deeper analysis.
April 2012 storm: we have observed a positive effect associated to its main phase but is only appreciated at the lower latitudes (Figure 4(b)). The recovery phases is characterized by a first long negative phase, followed by a positive phase that only appear in the lower latitudes and again a negative phase. These three phases had a variation of around 50%. At lower latitudes (up to 38º), sTEC depletions were observed during the 23rd to 24th night coinciding with the main phase of the geomagnetic storm (Figure 4 (c)). PPP errors of 20 to 30cm in altitude in some stations of lower latitude occur at the same time as sTEC depletion related irregularities (Figure 4 (d)).
(a) (c) (a) (c) Storm of 24 April 2012 Storm of 15 December 2006
