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Found 21 entries in the Bibliography.
Showing entries from 1 through 21
On the impact of meridional wind circulation changes in the electron density distribution over the Indian equatorial and low latitude ionospheric region during a severe geomagnetic storm
Using a suite of instruments, which included a chain of ground-based dual-frequency GPS receivers, and magnetometers, we have studied the importance of thermospheric meridional wind circulation in controlling the distribution of plasma over the Indian low latitude ionospheric regions during the period of a severe geomagnetic storm. The storm on 15 May 2005, which had its onset coinciding with the local noon time sector for the Indian ionospheric zone, was a severe geomagnetic storm with symH ∼ - 305 nT. A steep increase i ...
Published by: Advances in Space Research Published on: oct
YEAR: 2022   DOI: 10.1016/j.asr.2022.06.027
Compositional disturbances; Equatorial ionosphere; geomagnetic storm; total electron content
Quantification of the role of gravity wave induced TIDs in modulating ESF day to day variability during geomagnetically disturbed periods
The control of magnetic disturbance induced seed perturbations on the daily variation in night-time ionization irregularity occurrence is studied using ionosonde data and TIMED/GUVI neutral density data at the magnetic equatorial region, Trivandrum. The study reveals that there is a requisite threshold seed amplitude for ESF to occur at a particular altitude and this requisite seed increases as the altitude decreases. This dependence of requisite seed perturbation on altitude for multiple years, which incorporates the electr ...
Published by: Advances in Space Research Published on: mar
YEAR: 2022   DOI: 10.1016/j.asr.2021.11.038
Equatorial ionosphere; Equatorial Spread F; Geomagnetically disturbed period; neutral density
A Synoptic-Scale Wavelike Structure in the Nighttime Equatorial Ionization Anomaly
Both ground- and satellite-based airglow imaging have significantly contributed to understanding the low-latitude ionosphere, especially the morphology and dynamics of the equatorial ionization anomaly (EIA). The NASA Global-scale Observations of the Limb and Disk (GOLD) mission focuses on far-ultraviolet airglow images from a geostationary orbit at 47.5°W. This region is of particular interest at low magnetic latitudes because of the high magnetic declination (i.e., about -20°) and proximity of the South Atlantic magnetic ...
Rodríguez-Zuluaga, J.; Stolle, C.; Yamazaki, Y.; Xiong, C.; England, S.;
Published by: Earth and Space Science Published on:
YEAR: 2021   DOI: 10.1029/2020EA001529
equatorial plasma bubbles; Equatorial ionization anomaly; Equatorial ionosphere; forcing from below; wave structure
Modeling the Impact of Metallic Ion Layers on Equatorial Spread With SAMI3/ESF
The impact of region metal ion layers on the development of equatorial plasma bubbles is investigated using the SAMI3/ESF model. We find that metal ion layers reduce the growth rate of the generalized Rayleigh-Taylor instability (GRTI) and act to suppress the development of equatorial plasma bubbles. This is consistent with ...
Huba, J.; Krall, J.; Drob, D.;
Published by: Geophysical Research Letters Published on: 02/2020
YEAR: 2020   DOI: 10.1029/2020GL087224
Equatorial ionosphere; Equatorial Spread F; metal ions; sporadic E
Global-scale Observations of the Equatorial Ionization Anomaly
Abstract The National Aeronautics and Space Administration Global-scale Observations of the Limb and Disk ultraviolet spectrograph has been imaging the equatorial ionization anomaly (EIA), regions of the ionosphere with enhanced electron density north and south of the magnetic equator, since October 2018. The initial 3 months of observations was during solar minimum conditions, and they included observations in December solstice of unanticipated variability and depleted regions. Depletions are seen on most nights, in contras ...
Eastes, R.; Solomon, S.; Daniell, R.; Anderson, D.; Burns, A.; England, S.; Martinis, C.; McClintock, W.;
Published by: Geophysical Research Letters Published on:
YEAR: 2019   DOI: https://doi.org/10.1029/2019GL084199
Equatorial ionosphere; ionospheric irregularities; ionospheric dynamics; Ionospheric storms; forecasting; airglow and aurora
The Morphology of Equatorial Plasma Bubbles - a review
Plasma bubbles that occur in the equatorial F-region make up one of the most distinguishing phenomena in the ionosphere. Bubbles represent plasma depletions with respect to the background ionosphere, and are the major source of electron density irregularities in the equatorial F-region. Such bubbles are seen as plasma depletion holes (in situ satellite observations), vertical plumes (radar observations), and emission-depletion bands elongated in the north-south direction (optical observations). However, no technique can o ...
Published by: Journal of Astronomy and Space Sciences Published on: 03/2013
YEAR: 2015   DOI: 10.5140/JASS.2015.32.1.13
Geomagnetic control of equatorial plasma bubble activity modeled by the TIEGCM with Kp
Describing the day-to-day variability of Equatorial Plasma Bubble (EPB) occurrence remains a significant challenge. In this study we use the Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIEGCM), driven by solar (F10.7) and geomagnetic (Kp) activity indices, to study daily variations of the linear Rayleigh-Taylor (R-T) instability growth rate in relation to the measured scintillation strength at five longitudinally distributed stations. For locations characterized ...
Carter, B.; Retterer, J.; Yizengaw, E.; Groves, K.; Caton, R.; McNamara, L.; Bridgwood, C.; Francis, M.; Terkildsen, M.; Norman, R.; Zhang, K.;
Published by: Geophysical Research Letters Published on: 08/2014
YEAR: 2014   DOI: 10.1002/2014GL060953
The Ionospheric Bubble Index deduced from magnetic field and plasma observations onboard Swarm
In the post-sunset tropical ionospheric F-region plasma density often exhibits depletions, which are usually called equatorial plasma bubbles (EPBs). In this paper we give an overview of the Swarm Level 2 Ionospheric Bubble Index (IBI), which is a standard scientific data of the Swarm mission. This product called L2-IBI is generated from magnetic field and plasma observations onboard Swarm, and gives information as to whether a Swarm magnetic field observation is affected by EPBs. We validate the performance of the L2-IBI ...
Park, J.; Noja, M.; Stolle, C.; Lühr, H.;
Published by: Earth, Planets and Space Published on: 11/2014
YEAR: 2013   DOI: 10.5047/eps.2013.08.005
Equatorial ionosphere; Plasma irregularity; topside ionosphere
GPS TEC near the crest of the EIA at 95\textdegreeE during the ascending half of solar cycle 24 and comparison with IRI simulations
Total electron content (TEC) data obtained from GPS dual frequency measurements during the ascending half of the solar cycle 24 from 2009 to 2012 over Dibrugarh (27.5\textdegreeN, 94.9\textdegreeE; 17.6\textdegreeN MLAT) have been used to study the diurnal, seasonal, annual and solar cycle variation of TEC. The measurements reported here are for the first time from the location situated at the poleward edge of the northern equatorial ionization anomaly (EIA) and within the peak region of the longitudinal wave number 4 (WN ...
Bhuyan, Pradip; Hazarika, Rumajyoti;
Published by: Advances in Space Research Published on: 10/2013
YEAR: 2013   DOI: 10.1016/j.asr.2013.06.029
Ion-neutral coupling during deep solar minimum
The equatorial ionosphere under conditions of deep solar minimum exhibits structuring due to tidal forces. Data from instruments carried by the Communication/Navigation Outage Forecasting System (C/NOFS) which was launched in April 2008 have been analyzed for the first 2 years following launch. The Planar Langmuir Probe (PLP), Ion Velocity Meter (IVM) and Vector Electric Field Investigation (VEFI) all detect periodic structures during the 2008\textendash2010 period which appear to be tides. However when the tidal features ...
Huang, Cheryl; Roddy, Patrick; Sutton, Eric; Stoneback, Russell; Pfaff, Robert; Gentile, Louise; Delay, Susan;
Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 10/2013
YEAR: 2013   DOI: 10.1016/j.jastp.2012.11.009
Equatorial ionosphere; Nonmigrating tides; Plasma depletions; thermosphere
Are plasma bubbles a prerequisite for the formation of broad plasma depletions in the equatorial F region?
Formation of broad plasma depletions (BPDs) at night in the equatorial F region is understood in association with plasma bubbles. However, we report BPDs that do not show a connection with bubbles. The characteristics of BPDs are investigated using the observations of the Communication/Navigation Outage Forecasting System (C/NOFS) satellite on 31 December 2008, 28 July 2010, and 1 February 2011. On those days, BPDs are detected in the longitude regions where C/NOFS did not detect bubbles prior to the detection of ...
Published by: Geophysical Research Letters Published on: 07/2014
YEAR: 2013   DOI: 10.1002/grl.50693
Signatures of equatorial plasma bubbles in VHF satellite scintillations and equatorial ionograms
Since their discovery in the 1970s, equatorial plasma bubbles (EPBs) have been invoked to explain the propagation of VHF signals on trans-equatorial circuits at night, and blamed for highly detrimental scintillation of VHF and GHz trans-ionospheric communications signals in equatorial regions. Over the last four decades, the properties of EPBs have been deduced by multiple techniques such as incoherent scatter radar, 630 nm airglow, depletions in GPS total electron content observations, VHF and GHz scintillations, and HF ...
McNamara, L.; Caton, R.; Parris, R.; Pedersen, T.; Thompson, D.; Wiens, K.; Groves, K.;
Published by: Radio Science Published on: 03/2013
YEAR: 2013   DOI: 10.1002/rds.v48.210.1002/rds.20025
Impacts of atmospheric ultrafast Kelvin waves on radio scintillations in the equatorial ionosphere
We present a statistical analysis of the amplitudes of GPS scintillations (S4 index) observed throughout 2008\textendash2010 using the satellite radio occultation measurements of the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC). Here, for the first time, periodic variability in the occurrence of S4 is investigated using these data. Significant variations of S4 with periods of 2.5\textendash4 days (quasi-3 days) are identified from the observations during postsunset hours (1900\textendas ...
Liu, Guiping; Immel, Thomas; England, Scott; Frey, Harald; Mende, Stephen; Kumar, Karanam; Ramkumar, Geetha;
Published by: Journal of Geophysical Research: Space Physics Published on: 02/2013
YEAR: 2013   DOI: 10.1002/jgra.50139
day-to-day variability; Equatorial ionosphere; scintillation; Ultra Fast Kelvin planetary wave
Nonmigrating tidal signatures in the magnitude and the inter-hemispheric asymmetry of the equatorial ionization anomaly
Based on nine years of observations from the satellites CHAMP and GRACE the tidal signatures in the magnitude and the inter-hemisphere asymmetry of the equatorial ionization anomaly (EIA) have been investigated in this study. The EIA magnitude parameters show longitudinal wavenumber 4 and 3 (WN4/WN3) patterns during the months around August and December, respectively, while for different EIA parameters the contributions of the various tidal parameters are different. For the crest- to-trough ratio (CTR) the dominating nonm ...
Published by: Annales Geophysicae Published on: 01/2013
YEAR: 2013   DOI: 10.5194/angeo-31-1115-2013
Atmospheric dynamics; Equatorial ionosphere; Ionosphere; ionosphere\textendashatmosphere interactions. Meteorology
Equatorial ionosphere responses to two magnetic storms of moderate intensity from conjugate point observations in Brazil
Equatorial ionospheric responses during two magnetic storms of moderate intensity are investigated, for the first time, by conjugate point observations in Brazil. The study focuses on storm-induced changes in the evening prereversal vertical drift, thermospheric trans-equatorial winds, spread F/plasma bubble irregularity development, electron density/plasma frequency heights, the EIA strength, and zonal plasma drifts. It is based on data obtained from five Digisondes operated in Brazil, three of them being part of a conju ...
Abdu, M.; Batista, I.; Bertoni, F.; Reinisch, B.; Kherani, E.; Sobral, J.;
Published by: Journal of Geophysical Research Published on: 05/2012
YEAR: 2012   DOI: 10.1029/2011JA017174
Equatorial ionosphere; Magnetic storms; plasma bubbles; plasma drifts; spread F; transequatorial winds
Coordinated UV imaging of equatorial plasma bubbles using TIMED/GUVI and DMSP/SSUSI
Comberiate, Joseph; Paxton, L.;
Published by: Space Weather Published on: Jan-01-2010
YEAR: 2010   DOI: 10.1029/2009SW000546
Equatorial ionosphere; ionospheric irregularities; scintillation
Neutral density depletions associated with equatorial plasma bubbles as observed by the CHAMP satellite
Using CHAMP observations from 2002 to 2005 we investigate neutral density depletions (NDDs) associated with equatorial plasma bubbles (EPBs). The seasonal–longitudinal distribution of NDDs generally follows that of EPBs. However, there are several important differences between them. The maximum NDD occurrence rate is much smaller than the maximum EPB occurrence. NDDs occur at latitudes north and south of the dip equator with an offset of about 15∘, which is collocated with the Appleton anomaly peaks and slightly poleward ...
Park, Jaeheung; Lühr, Hermann; Min, Kyoung;
Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on:
YEAR: 2010   DOI: https://doi.org/10.1016/j.jastp.2009.11.003
ionospheric irregularities; Equatorial ionosphere; thermospheric dynamics; ionosphere/atmosphere interactions
Formation of a plasma depletion shell in the equatorial ionosphere
An accurate description of the irregularity region defined by a plasma bubble is critically important in understanding the dynamics of the region and its effects on radio scintillation. Here we describe a plasma depletion region as a \textquotedblleftdepletion shell\textquotedblright and show how two-dimensional optical images from space can be used to define the shape of the depletion shell. Our simple model calculation demonstrates that the space-based optical observation can detect the plasma-depleted magnetic flux tub ...
Kil, Hyosub; Heelis, Roderick; Paxton, Larry; Oh, Seung-Jun;
Published by: Journal of Geophysical Research Published on: 11/2009
YEAR: 2009   DOI: 10.1029/2009JA014369
Equatorial ionosphere; plasma depletion shell; zonal shear flow
Wave structures of the plasma density and vertical E$\times$ B drift in low-latitude F region
We investigate the seasonal, longitudinal, local time (LT), and altitudinal variations of the F region morphology at low latitudes using data from the first Republic of China satellite (ROCSAT-1), Global Ultraviolet Imager (GUVI), on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite, and the Defense Meteorological Satellite Program (DMSP) F13 and F15 satellites. Signatures of the longitudinally periodic plasma density structure emerge before 0900 LT. The wave structure is established befo ...
Kil, H.; Talaat, E.; Oh, S.-J.; Paxton, L.; England, S.; Su, S.-Y.;
Published by: Journal of Geophysical Research Published on: Jan-01-2008
YEAR: 2008   DOI: 10.1029/2008JA013106
Ionospheric disturbances during the magnetic storm of 15 July 2000: Role of the fountain effect and plasma bubbles for the formation of large equatorial plasma density depletions
We investigate the role of the fountain effect and plasma bubbles for the formation of the large equatorial plasma depletions during the geomagnetic storm of 15 July 2000. The large equatorial plasma depletions are detected in the Atlantic sector on the night of the 15th by the Defense Meteorological Satellite Program (DMSP) F15 and the first Republic of China Satellite (ROCSAT-1). The observations show discontinuous drop of the plasma density at the walls of the depletions, flat plasma density inside the depletions, and ...
Published by: Journal of Geophysical Research Published on: 12/2006
YEAR: 2006   DOI: 10.1029/2006JA011742
Equatorial ionosphere; geomagnetic storm; ionospheric disturbances
Characteristics of the storm-induced big bubbles (SIBBs)
Large equatorial plasma depletions, referred to as storm-induced big bubbles (SIBBs), are detected from the Defense Meteorological Satellite Program F15 and from the first Republic of China Satellite during the large magnetic storms of 31 March 2001, 29 October 2003, and 20 November 2003. They occur in the equatorial region at night, are elongated in the north-south direction, have steep walls, and always coexist with plasma bubbles. These observations are consistent with the SIBB characteristics described in the companio ...
Kil, Hyosub; Paxton, L.; Su, Shin-Yi; Zhang, Yongliang; Yeh, Hweyching;
Published by: Journal of Geophysical Research Published on: 10/2006
YEAR: 2006   DOI: 10.1029/2006JA011743