Sources of F-region height changes during geomagnetic storms at mid latitudes

2008 ◽  
pp. 247-258 ◽  
Author(s):  
Mariangel Fedrizzi ◽  
T. J. Fuller-Rowell ◽  
Naomi Maruyama ◽  
Mihail Codrescu ◽  
Hargobind Khalsa
Keyword(s):  
Geomagnetic Storms ◽  
F Region

scholarly journals Observations of the F-region ionospheric irregularities in the South American sector during the October 2003 "Halloween Storms"

2009 ◽  
Vol 27 (12) ◽  
pp. 4463-4477 ◽  
Author(s):  
Y. Sahai ◽  
F. Becker-Guedes ◽  
P. R. Fagundes ◽  
A. J. de Abreu ◽  
R. de Jesus ◽  
...  
Keyword(s):  
Geomagnetic Storms ◽  
Ionospheric Irregularities ◽  
South American ◽  
The South ◽  
Geomagnetic Disturbances ◽  
Plasma Bubbles ◽  
F Region ◽  
A Chain ◽  
Ionospheric Sounding ◽  
Gps Observations

Abstract. The response of the ionospheric F-region in the South American sector during the super geomagnetic storms on 29 and 30 October 2003 is studied in the present investigation. In this paper, we present ionospheric sounding observations during the period 29–31 October 2003 obtained at Palmas (a near equatorial location) and Sao Jose dos Campos (a location under the southern crest of the equatorial ionospheric anomaly), Brazil, along with observations during the period 27–31 October 2003 from a chain of GPS stations covering the South American sector from Imperatriz, Brazil, to Rio Grande, Argentina. Also, complementary observations that include sequences of all-sky images of the OI 777.4 and 630.0 nm emissions observed at El Leoncito, Argentina, on the nights of 28–29 (geomagnetically quiet night) and 29–30 (geomagnetically disturbed night) October 2003, and ion densities observed in the South American sector by the DMSP F13, F14 and F15 satellites orbiting at about 800 km on 29 and 30 October 2003 are presented. In addition, global TEC maps derived from GPS observations collected from the global GPS network of International GPS Service (IGS) are presented, showing widespread and drastic TEC changes during the different phases of the geomagnetic disturbances. The observations indicate that the equatorial ionospheric irregularities or plasma bubbles extend to the Argentinean station Rawson (geom. Lat. 33.1° S) and map at the magnetic equator at an altitude of about 2500 km.

scholarly journals Generation of large-scale equatorial F-region plasma depletions during lowrange spread-F season

2004 ◽  
Vol 22 (1) ◽  
pp. 15-23 ◽  
Author(s):  
Y. Sahai ◽  
P. R. Fagundes ◽  
J. R. Abalde ◽  
A. A. Pimenta ◽  
J. A. Bittencourt ◽  
...  
Keyword(s):  
Large Scale ◽  
Ionospheric Plasma ◽  
Geomagnetic Storms ◽  
Atmospheric Composition ◽  
F Region ◽  
Range Type ◽  
June Solstice ◽  
Radio Signature ◽  
Spread F ◽  
Plasma Depletions

Abstract. All-sky imaging observations of the F-region OI 630nm nightglow emission allow us to visualize large-scale equatorial plasma depletions, generally known as trans-equatorial plasma bubbles. Strong range type spread-F is the radio signature of these (magnetically) north-south aligned plasma depletions. An extensive database of the OI 630nm emission all-sky imaging observations has been obtained at Cachoeira Paulista (22.7°S, 45.0°W; dip latitude ∼16°S), Brazil, between the years 1987 and 2000. An analysis of these observations revealed that relatively few large-scale ionospheric plasma depletions occur during the months of May to August (southern winter, June solstice) in the Brazilian sector. Of the few that are observed during these months, some occur in association with geomagnetic storms and some do not. In this paper, a detailed analysis of the events when large-scale ionospheric plasma depletions were initiated and evolved during the June solstice periods are presented and discussed.Key words. Atmospheric composition and chemistry (airglow and aurora). Ionosphere (equatorial ionosphere; ionospheric irregularities)

Behavior of the ionospheric F region prior to geomagnetic storms

2019 ◽  
Vol 64 (7) ◽  
pp. 1375-1387 ◽  
Author(s):  
A.D. Danilov ◽  
A.V. Konstantinova
Keyword(s):  
Geomagnetic Storms ◽  
F Region

Disturbances in the ionospheric F-region peak heights in the American longitudinal sector during geomagnetic storms of September 2005

2011 ◽  
Vol 48 (7) ◽  
pp. 1184-1195 ◽  
Author(s):  
M.V. Klimenko ◽  
V.V. Klimenko ◽  
K.G. Ratovsky ◽  
L.P. Goncharenko
Keyword(s):  
Geomagnetic Storms ◽  
F Region ◽  
Longitudinal Sector

scholarly journals Comparison of model electron densities and temperatures with Millstone Hill observations during undisturbed periods and the geomagnetic storms of 16−23 March and 6−12 April 1990

1997 ◽  
Vol 15 (3) ◽  
pp. 327-344 ◽  
Author(s):  
A. V. Pavlov ◽  
M. J. Buonsanto
Keyword(s):  
Electron Density ◽  
Geomagnetic Storms ◽  
Collision Frequency ◽  
Boltzmann Distribution ◽  
Solar Flux ◽  
Vibrationally Excited ◽  
Model Calculations ◽  
F Region ◽  
Vibrational Levels ◽  
Flux Model

Abstract. Measurements of F-region electron density and temperature at Millstone Hill are compared with results from the IZMIRAN time-dependent mathematical model of the Earth's ionosphere and plasmasphere during the periods 16–23 March and 6–12 April 1990. Each of these two periods included geomagnetically quiet intervals followed by major storms. Satisfactory agreement between the model and the data is obtained during the quiet intervals, provided that the recombination rate of O+(4S) ions was decreased by a factor of 1.5 at all altitudes during the nighttime periods 17–18 March, 19–20 March, 6–8 April and 8–9 April in order to increase the NmF2 at night better to match observations. Good model/data agreement is also obtained during the storm periods when vibrationally excited N2 brings about factor-of-2-4 reductions in daytime NmF2. Model calculations are carried out using different expressions for the O+ – O collision frequency for momentum transfer, and the best agreement between the electron-density measurements and the model results is obtained when the CEDAR interim standard formula for the O‡+ – O collision frequency is used. Deviations from the Boltzmann distribution for the ®rst ®ve vibrational levels of N2 collision frequency is used. Deviations from the Boltzmann distribution for the first five vibrational levels of j were calculated. The calculated distribution is highly non-Boltzmann at vibrational levels j > 2 and the Boltzmann distribution assumption results in the increase of 10–30% in calculated NmF2 during the storm-time periods. During the March storm at solar maximum the model results obtained using the EUVAC solar flux model agree a little better with the observations in comparison with the EUV94 solar flux model. For the April storm period of moderate solar activity the EUV94X model results agree better with the observations in comparison to the EUVAC model.

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