Daytime vertical <b>E</b> × <b>B</b> drift velocities inferred from ground‐based magnetometer observations at low latitudes

Anderson, D. N.; Anghel, A.; Chau, Jorge L.; Veliz, O.

doi:10.1029/2004sw000095

Cited by 190 publications

(217 citation statements)

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“…In this work we retrieved Jicamarca-Piura H data from Jicamarca Radio Observatory available online at http://jro.igp.gob.pe/ database/magnetometer/html/magdata.htm. The basis of this method was first proposed by Rastogi and Klobuchar (1990) and many studies used this methodology to calculate equatorial vertical drifts which are directly proportional to the zonal electric field through the relationship V D = E/B, where V D is the vertical drift, E is the zonal electric field and B is the magnitude of the geomagnetic field at the point on the geomagnetic equator (Anderson et al, 2002(Anderson et al, , 2004Huang et al, 2005b). Since the disturbances in H are related to disturbances in the zonal electric field, the H provides a qualitative manner to verify the occurrence of penetration electric fields in the equatorial ionosphere.…”

Section: Experimental Datamentioning

confidence: 99%

Total electron content responses to HILDCAAs and geomagnetic storms over South America

2017

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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 stormtime 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 / N 2 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.

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Section: Experimental Datamentioning

confidence: 99%

Total electron content responses to HILDCAAs and geomagnetic storms over South America

2017

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“…As such, 150-km echoes facilitate an economical and reliable way of measuring these drifts, particularly during the day. For example, Anderson et al (2004) have used many days of drift data obtained from 150-km echoes, to find a reliable empirical model to derive F-region zonal electric fields from magnetometer H observations. Although 150-km echoes have been observed and studied for many years, the physical mechanism which causes them is still unknown.…”

Section: Introductionmentioning

confidence: 99%

Statistics of 150-km echoes over Jicamarca based on low-power VHF observations

Chau

Kudeki

2006

Ann. Geophys.

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Abstract. In this work we summarize the statistics of the socalled 150-km echoes obtained with a low-power VHF radar operation at the Jicamarca Radio Observatory (11.97 • S, 76.87 • W, and 1.3 • dip angle at 150-km altitude) in Peru. Our results are based on almost four years of observations between August 2001 and July 2005 (approximately 150 days per year). The majority of the observations have been conducted between 08:00 and 17:00 LT. We present the statistics of occurrence of the echoes for each of the four seasons as a function of time of day and altitude. The occurrence frequency of the echoes is ∼75% around noon and start decreasing after 15:00 LT and disappear after 17:00 LT in all seasons. As shown in previous campaign observations, the 150-echoes appear at a higher altitude (>150 km) in narrow layers in the morning, reaching lower altitudes (∼135 km) around noon, and disappear at higher altitudes (>150 km) after 17:00 LT. We show that although 150-km echoes are observed all year long, they exhibit a clear seasonal variability on altitudinal coverage and the percentage of occurrence around noon and early in the morning. We also show that there is a strong day-to-day variability, and no correlation with magnetic activity. Although our results do not solve the 150-km riddle, they should be taken into account when a reasonable theory is proposed.

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“…In order to verify the disturbed zonal electric fields in South America during the superstorm, ionospheric vertical drift data obtained from modeling results are used in the analysis. The vertical drifts were inferred from H magnetometer data (Jicamarca-Piura) following the methodology presented by Anderson et al (2004). Also used were vertical drifts measured by the Jicamarca ISR.…”

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Storm-time total electron content and its response to penetration electric fields over South America

et al. 2011

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Abstract. In this work the response of the ionosphere due to the severe magnetic storm of 7-10 November 2004 is investigated by analyzing GPS Total Electron Content (TEC) maps constructed for the South America sector. In order to verify the disturbed zonal electric fields in South America during the superstorm, ionospheric vertical drift data obtained from modeling results are used in the analysis. The vertical drifts were inferred from H magnetometer data (Jicamarca-Piura) following the methodology presented by Anderson et al. (2004). Also used were vertical drifts measured by the Jicamarca ISR. Data from a digisonde located at São Luís, Brazil (2.33 • S, 44.2 • W, dip latitude 0.25 • ) are presented to complement the Jicamarca equatorial data. Penetration electric fields were observed by the comparison between the equatorial vertical drifts and the Interplanetary Electric Field (IEF). The TEC maps obtained from GPS data reflect the ionospheric response over the South America low-latitude and equatorial region. They reveal unexpected plasma distributions and TEC levels during the main phase of the superstorm on 7 November, which is coincident with the local post-sunset hours. At this time an increase in the prereversal enhancement was expected to develop the Equatorial Ionization Anomaly (EIA) but we observed the absence of EIA. The results also reveal well known characteristics of the plasma distributions on 8, 9, and 10 November. The emphasized features are the expansion and intensification of EIA due to prompt penetration electric fields on 9 November and the inhibition of EIA during post-sunset hours on 7, 8, and 10 November. One important result is that the TEC maps provided a bi-dimensional view of the ionospheric changes offering a spatial description of the electrodynamics involved, Correspondence to: P. M. de Siqueira (patricia.mara@dae.inpe.br) which is an advantage over TEC measured by isolated GPS receivers.

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Daytime vertical E × B drift velocities inferred from ground‐based magnetometer observations at low latitudes

Cited by 190 publications

References 22 publications

Total electron content responses to HILDCAAs and geomagnetic storms over South America

Total electron content responses to HILDCAAs and geomagnetic storms over South America

Statistics of 150-km echoes over Jicamarca based on low-power VHF observations

Storm-time total electron content and its response to penetration electric fields over South America

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