Total electron content responses to HILDCAAs and geomagnetic storms over South America
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Published:2017-12-07
Issue:6
Volume:35
Page:1309-1326
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ISSN:1432-0576
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Container-title:Annales Geophysicae
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language:en
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Short-container-title:Ann. Geophys.
Author:
de Siqueira Negreti Patricia Mara,de Paula Eurico Rodrigues,Candido Claudia Maria Nicoli
Abstract
Abstract. Total electron content (TEC) is extensively used to monitor the ionospheric behavior under geomagnetically quiet and disturbed conditions. This subject is of greatest importance for space weather applications. Under disturbed conditions the two main sources of electric fields, which are responsible for changes in the plasma drifts and for current perturbations, are the short-lived prompt penetration electric fields (PPEFs) and the longer-lasting ionospheric disturbance dynamo (DD) electric fields. Both mechanisms modulate the TEC around the globe and the equatorial ionization anomaly (EIA) at low latitudes. In this work we computed vertical absolute TEC over the low latitude of South America. The analysis was performed considering HILDCAA (high-intensity, long-duration, continuous auroral electrojet (AE) activity) events and geomagnetic storms. The characteristics of storm-time TEC and HILDCAA-associated TEC will be presented and discussed. For both case studies presented in this work (March and August 2013) the HILDCAA event follows a geomagnetic storm, and then a global scenario of geomagnetic disturbances will be discussed. Solar wind parameters, geomagnetic indices, O ∕ N2 ratios retrieved by GUVI instrument onboard the TIMED satellite and TEC observations will be analyzed and discussed. Data from the RBMC/IBGE (Brazil) and IGS GNSS networks were used to calculate TEC over South America. We show that a HILDCAA event may generate larger TEC differences compared to the TEC observed during the main phase of the precedent geomagnetic storm; thus, a HILDCAA event may be more effective for ionospheric response in comparison to moderate geomagnetic storms, considering the seasonal conditions. During the August HILDCAA event, TEC enhancements from ∼ 25 to 80 % (compared to quiet time) were observed. These enhancements are much higher than the quiet-time variability observed in the ionosphere. We show that ionosphere is quite sensitive to solar wind forcing and considering the events studied here, this was the most important source of ionospheric responses. Furthermore, the most important source of TEC changes were the long-lasting PPEFs observed on August 2013, during the HILDCAA event. The importance of this study relies on the peculiarity of the region analyzed characterized by high declination angle and ionospheric gradients which are responsible for creating a complex response during disturbed periods.
Publisher
Copernicus GmbH
Subject
Space and Planetary Science,Earth and Planetary Sciences (miscellaneous),Atmospheric Science,Geology,Astronomy and Astrophysics
Reference51 articles.
1. Abdu, M. A., Walker, G. O., Reddy, B. M., de Paula, E. R., Sobral, J. H. A., Fejer, B. G., and Szuszczewicz, E. P.: Global scale equatorial ionization anomaly (EIA) response to magnetospheric disturbances based on the May–June 1987 SUNDIAL-coordinated observations, Ann. Geophys., 11, 585–594, 1993. 2. Anderson, D., Anghel, A., Yumoto, K., Ishitsuka, M., and Kudeki, E.: Estimating daytime vertical EtimesB drift velocities in the equatorial F-region using ground-based magnetometer observations, Geophys. Res. Lett., 29, 1–4, https://doi.org/10.1029/2001GL014562, 2002. 3. Anderson, D., Anghel, A., Chau, J., and Veliz, O.: Daytime vertical E × B drift velocities inferred from ground based magnetometer observations at low latitudes, Adv. Space Res., 2, S11001, https://doi.org/10.1029/2004SW000095, 2004. 4. Balan, N., Batista, I. S., Abdu, M. A., MacDougall, J., and Bailey, G. J.: Physical mechanism and statistics of occurrence of an additional layer in the equatorial ionosphere, J. Geophys. Res., 103, 169–29,181, https://doi.org/10.1029/98JA02823, 1998. 5. Blanc, M.: Magnetospheric convection effects at mid-latitudes, 1. Saint-Santin observations, J. Geophys. Res., 88, 211–213, 1983.
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