Ionospheric irregularities: The role of the equatorial ionization anomaly

Rao, P. V. S. Rama; Jayachandran, P. T.; Ram, P. Sri

doi:10.1029/97rs00665

Cited by 28 publications

(13 citation statements)

References 21 publications

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“…Prakash et al (2009) suggested, by performing model calculations, that PRE tends to be strengthened with the increasing flux tube integrated conductivity of the tropical F-region. A statistical analysis performed by Rama Rao et al (1997) showed that the peak density of the F2-layer near and inside the EIA crests was strengthened during evening hours on ESF days. Stolle et al (2008) investigated a typical response time of observed EIA to EEJ variations and they showed that EIA decays significantly within approximately 2 h after CEJ onsets.…”

Section: Discussionmentioning

confidence: 99%

“…Bittencourt and Abdu (1981) reported that the time variation of h F (dh'F/dt) agrees well with the E × B drift of PRE when h F exceeds 300 km. Many earlier studies have utilized dh'F/dt for evaluating the E × B drift of PRE with ionosonde observation (e.g., Rama Rao et al, 1997). During the nighttime, the lower edge of the F-region echo trace at CPN is generally below the frequency of 2.0 MHz, which is the start frequency of the ionosonde installed at CPN.…”

Section: Data Set and Analysis Methodsmentioning

confidence: 99%

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Relationships between pre-sunset electrojet strength, pre-reversal enhancement and equatorial spread-F onset

et al. 2010

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Abstract. The virtual height of the bottom side F-region (h F ) and equatorial spread-F (ESF) onsets at Chumphon (10.7 • N, 99.4 • E; 3.3 • N magnetic latitude) were compared with the behaviour of equatorial electrojet (EEJ) ground strength at Phuket (8.1 • N, 98.3 • E; 0.1 • N magnetic latitude) during the period from November 2007 to October 2008. Increase in the F-layer height and ESF onsets during the evening hours were well connected with the EEJ ground strength before sunset, namely, both the height increase and ESF onsets were suppressed when the integrated EEJ ground strength for the period from 1 to 2 h prior to sunset was negative. The finding suggests observationally that the pre-sunset E-region dynamo current and/or electric field are related to the F-region dynamics and ESF onsets around sunset.

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Section: Discussionmentioning

confidence: 99%

Section: Data Set and Analysis Methodsmentioning

confidence: 99%

Relationships between pre-sunset electrojet strength, pre-reversal enhancement and equatorial spread-F onset

et al. 2010

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“…The initial guess should be able to produce high temporal and spatial variability of the ionosphere. This fact is more important for the Indian region which falls in equatorial ionospheric anomaly (EIA) belt [ Rama Rao et al , 1997]. In addition to this, there is another way to incorporate the additional information into the system via a prior model that includes the information about the desired solution [ Shieh et al , 2006].…”

Section: Tomography Modelmentioning

confidence: 99%

Two‐dimensional ionospheric tomography over the low‐latitude Indian region: An intercomparison of ART and MART algorithms

Das

Shukla

2011

Radio Science

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[1] Single-frequency users of a satellite-based augmentation system (SBAS) rely on ionospheric models to mitigate the delay due to the ionosphere. The ionosphere is the major source of range and range rate errors for users of the Global Positioning System (GPS) who require high-accuracy positioning. The purpose of the present study is to develop a tomography model to reconstruct the total electron content (TEC) over the low-latitude Indian region which lies in the equatorial ionospheric anomaly belt. In the present study, the TEC data collected from the six TEC collection stations along a longitudinal belt of around 77 degrees are used. The main objective of the study is to find out optimum pixel size which supports a better reconstruction of the electron density and hence the TEC over the low-latitude Indian region. Performance of two reconstruction algorithms Algebraic Reconstruction Technique (ART) and Multiplicative Algebraic Reconstruction Technique (MART) is analyzed for different pixel sizes varying from 1 to 6 degrees in latitude. It is found from the analysis that the optimum pixel size is 5°× 50 km over the Indian region using both ART and MART algorithms.Citation: Das, S. K., and A. K. Shukla (2011), Two-dimensional ionospheric tomography over the low-latitude Indian region: An intercomparison of ART and MART algorithms, Radio Sci., 46, RS2005,

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“…The growth rate of the R‐T instability depends on the external driving forces such as neutral wind [ Rama Rao et al , 1997], electric and magnetic fields, together with background ionospheric properties for example the flux tube integrated Pedersen conductivity and upward plasma density gradients [ Sultan , 1996]. For the PBs and associated irregularities at middle latitude, one type is identified as the extension of equatorial irregularities since an equatorial plasma bubble (PB) can rise to a high apex height and extend to higher latitudes along the magnetic field line [ Huang et al , 2007].…”

Section: Introductionmentioning

confidence: 99%

Characterizing the 10 November 2004 storm‐time middle‐latitude plasma bubble event in Southeast Asia using multi‐instrument observations

Ning

Zhao

et al. 2009

J. Geophys. Res.

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The development and dynamics of ionospheric plasma bubble (PB) irregularity during the super storm of 7–11 November 2004 are investigated using the data from a multi‐instrument network operated in Southeast Asia. Analysis of fluctuations in Global Positioning System total electron content (GPS TEC), ionosonde, GPS scintillation, and in situ satellite density data indicates a series of intense PB‐associated irregularities at equatorial, low, and middle latitudes in the Japanese longitude on 10 November. However, in the Chinese sector, the scintillations and PB irregularities are confined within the range of 20–50°N in geographic latitude and 110–125°E in geographic longitude. The absence of equatorial PB irregularities in this sector shows a major difference from that in the close‐by longitude Japanese sector. In the Southern Hemisphere Australian sector, the irregularities occurrence is present as a symmetrical distribution at conjugate latitudes. Combined analysis of the data from Osan and Wuhan ionosondes illustrates that the middle‐latitude spread F irregularities initially develop at the lower part of the F region and then distribute in the whole F region. This initiation of spread F at lower altitudes indicates that the middle‐latitude PB‐associated irregularities are locally generated. These results together with the irregularities occurrence sequence from higher to lower latitudes, and the onset time delay of several hours implies that the presence of PB‐associated irregularities within a latitude range of 20–50°N in the Chinese sector cannot be attributed to the effects of prompt penetration electric fields (PPEFs), although the equatorial PBs in the close‐by longitude are seen to be associated with PPEFs. The possible mechanism is the F region plasma instabilities triggered by wave structures, which act as an external driving force and seed active plasma dynamics and instability growth at middle latitude.

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Ionospheric irregularities: The role of the equatorial ionization anomaly

Cited by 28 publications

References 21 publications

Relationships between pre-sunset electrojet strength, pre-reversal enhancement and equatorial spread-F onset

Relationships between pre-sunset electrojet strength, pre-reversal enhancement and equatorial spread-F onset

Two‐dimensional ionospheric tomography over the low‐latitude Indian region: An intercomparison of ART and MART algorithms

Characterizing the 10 November 2004 storm‐time middle‐latitude plasma bubble event in Southeast Asia using multi‐instrument observations

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