Geomagnetic storms in the Antarctic F-region. II. Physical interpretation

Rodger, A. S.; Wrenn, G. L.; Rishbeth, H.

doi:10.1016/0021-9169(89)90002-0

Cited by 84 publications

(70 citation statements)

References 54 publications

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“…Such motions of the trough during storms are well known effects (Moffett and Quegan, 1983;Whalen, 1989), and particularly so in the Wallops Island longitude sector (Mendillo et al, 1974;Foster et al, 1994;Baumgardner et al, 2007). Equatorward motions of the trough and its auroral-precipitationinduced poleward wall also occur in the Southern Hemisphere, as documented clearly in ionospheric storm effects upon NmF2 in the study by Rodger et al (1989). An excellent review of overall trough effects has recently appeared in Rodger (2008).…”

Section: Comparisons Of Characteristic Storm Patternsmentioning

confidence: 85%

“…These storm mechanisms are discussed in detail in the reviews by Prölss (1995), Mendillo (2006) and, of particular relevance to this study, in the papers by Wrenn et al (1987) and Rodger et al (1989) for sites in the Southern Hemisphere. First, we point to the component of the positive phase that arises from the soft precipitation of low energy magnetosheath plasma that ionizes the thermosphere at F-layer heights.…”

Section: Comparisons Of Characteristic Storm Patternsmentioning

confidence: 91%

“…The average depletions are less pronounced each day (∼ −20%, −15%, −5%) as the thermosphere recovers. Modulating these broad photo-chemical depletions (termed the "DC negative phase" by Rodger et al, 1989) are the local time ("AC negative phase") effects of equatorward motions of the ionospheric trough to the latitudes of Wallops Island and Hobart (L ∼ 2.5 to 3) near 03:00 local time. Such motions of the trough during storms are well known effects (Moffett and Quegan, 1983;Whalen, 1989), and particularly so in the Wallops Island longitude sector (Mendillo et al, 1974;Foster et al, 1994;Baumgardner et al, 2007).…”

Section: Comparisons Of Characteristic Storm Patternsmentioning

confidence: 99%

“…The effects of auroral energy input (particles and electric fields) that lead to heating the thermosphere, changing composition and enhancing loss, appears to be somewhat more prominent in the Southern Hemisphere. This is perhaps due to the influence of the magnetic field geometry in the Southern Hemisphere being so different from that in the Northern Hemisphere, and particularly so at the geographic latitudes of auroral input (Rodger et al, 1989). Thus effects of heating become more noticeable with the nighttime SC events that lead to the NoPositive-Phase (NPP) types of storms (Mendillo, 1973).…”

Section: Overall Summary Of Characteristic Featuresmentioning

confidence: 99%

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Ionospheric storms at geophysically-equivalent sites – Part 2: Local time storm patterns for sub-auroral ionospheres

Mendillo

Narvaez

2010

Ann. Geophys.

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Abstract. The response of the mid-latitude ionosphere to geomagnetic storms depends upon several pre-storm conditions, the dominant ones being season and local time of the storm commencement (SC). The difference between a site's geographic and geomagnetic latitudes is also of major importance since it governs the blend of processes linked to solar production and magnetospheric input, respectively. Case studies of specific storms using ionospheric data from both hemispheres are inherently dominated by seasonal effects and the various local times versus longitude of the SCs. To explore inter-hemispheric consistency of ionospheric storms, we identify "geophysically-equivalent-sites" as locations where the geographic and geomagnetic latitudes have the same relationship to each other in both hemispheres. At the longitudes of the dipole tilt, the differences between geographic and geomagnetic latitudes are at their extremes, and thus these are optimal locations to see if pre-conditioning and/or storm-time input are the same or differ between the hemispheres.In this study, we use ionosonde values of the F2-layer maximum electron density (NmF2) to study geophysical equivalency at Wallops Island (VA) and Hobart (Tasmania), using statistical summaries of 206 events during solar cycle #20. We form average patterns of NmF2 (%) versus local time over 7-day storm periods that are constructed in ways that enhance the portrayal of the average characteristic features of the positive and negative phases of ionospheric storms. The results show a consistency between four local time characteristic patterns of storm-induced perturbations, and thus for the average magnitudes and time scales of the processes that cause them in each hemisphere. Subtle differences linked to small departures from pure geophysical equivalency point to a possible presence of hemispheric asymmetries governedCorrespondence to: C. Narvaez (cnarvaez@bu.edu) by the non-mirror-image of geomagnetic morphology in each hemisphere.

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Section: Comparisons Of Characteristic Storm Patternsmentioning

confidence: 85%

Section: Comparisons Of Characteristic Storm Patternsmentioning

confidence: 91%

Section: Comparisons Of Characteristic Storm Patternsmentioning

confidence: 99%

Section: Overall Summary Of Characteristic Featuresmentioning

confidence: 99%

See 2 more Smart Citations

Ionospheric storms at geophysically-equivalent sites – Part 2: Local time storm patterns for sub-auroral ionospheres

Mendillo

Narvaez

2010

Ann. Geophys.

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“…Rodger et al (1989) suggested that the seasonal effect is caused by the movement of the bulge by transequatorial summer-to-winter wind field. The summerto-winter wind hinders the bulge propagation towards lower latitudes in winter and makes for the equatorward propagation in summer.…”

Section: Discussionmentioning

confidence: 99%

Time delay and duration of ionospheric total electron content responses to geomagnetic disturbances

2010

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Abstract. Although positive and negative signatures of ionospheric storms have been reported many times, global characteristics such as the time of occurrence, time delay and duration as well as their relations to the intensity of the ionospheric storms have not received enough attention. The 10 years of global ionosphere maps (GIMs) of total electron content (TEC) retrieved at Jet Propulsion Laboratory (JPL) were used to conduct a statistical study of the time delay of the ionospheric responses to geomagnetic disturbances. Our results show that the time delays between geomagnetic disturbances and TEC responses depend on season, magnetic local time and magnetic latitude. In the summer hemisphere at mid-and high latitudes, the negative storm effects can propagate to the low latitudes at post-midnight to the morning sector with a time delay of 4-7 h. As the earth rotates to the sunlight, negative phase retreats to higher latitudes and starts to extend to the lower latitude toward midnight sector. In the winter hemisphere during the daytime and after sunset at mid-and low latitudes, the negative phase appearance time is delayed from 1-10 h depending on the local time, latitude and storm intensity compared to the same area in the summer hemisphere. The quick response of positive phase can be observed at the auroral area in the night-side of the winter hemisphere. At the low latitudes during the dawn-noon sector, the ionospheric negative phase responses quickly with time delays of 5-7 h in both equinoctial and solsticial months.Our results also manifest that there is a positive correlation between the intensity of geomagnetic disturbances and the time duration of both the positive phase and negative phase. The durations of both negative phase and positive phase have clear latitudinal, seasonal and magnetic local time (MLT) dependence. In the winter hemisphere, long durations for the positive phase are 8-11 h and 12-14 h during the daytime at middle and high latitudes for 20≤Ap<40 and Ap≥40.

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F₂ region response to geomagnetic disturbances across Indian latitudes: O(¹S) dayglow emission

2016

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The morphology of ionospheric storms has been investigated across equatorial and low latitudes of Indian region. The deviation in F2 region characteristic parameters (foF2 and h′F) along with modeled green line dayglow emission intensities is examined at equatorial station Thiruvananthapuram (8.5°N, 76.8°E, 0.63°S geomagnetic latitude) and low‐latitude station Delhi (28.6°N, 77.2°E,19.2°N geomagnetic latitude) during five geomagnetic storm events. Both positive and negative phases have been noticed in this study. The positive storm phase over equatorial station is found to be more frequent, while the drop in ionization in most of the cases was observed at low‐latitude station. It is concluded that the reaction as seen at different ionospheric stations may be quite different during the same storm depending on both the geographic and geomagnetic coordinates of the station, storm intensity, and the storm onset time. Modulation in the F2 layer critical frequency at low and equatorial stations during geomagnetic disturbance of 20–23 November 2003 was caused by the storm‐induced changes in O/N2. It is also found that International Reference Ionosphere 2012 model predicts the F2 layer characteristic (foF2 and h′F) parameters at both the low and equatorial stations during disturbed days quite reasonably. A simulative approach in GLOW model developed by Solomon is further used to estimate the changes in the volume emission rate of green line dayglow emission under quiet and strong geomagnetic conditions. It is found that the O(1S) dayglow thermospheric emission peak responds to varying geomagnetic conditions.

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Geomagnetic storms in the Antarctic F-region. II. Physical interpretation

Cited by 84 publications

References 54 publications

Ionospheric storms at geophysically-equivalent sites – Part 2: Local time storm patterns for sub-auroral ionospheres

Ionospheric storms at geophysically-equivalent sites – Part 2: Local time storm patterns for sub-auroral ionospheres

Time delay and duration of ionospheric total electron content responses to geomagnetic disturbances

F₂ region response to geomagnetic disturbances across Indian latitudes: O(¹S) dayglow emission

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Geomagnetic storms in the Antarctic F-region. II. Physical interpretation

Cited by 84 publications

References 54 publications

Ionospheric storms at geophysically-equivalent sites – Part 2: Local time storm patterns for sub-auroral ionospheres

Ionospheric storms at geophysically-equivalent sites – Part 2: Local time storm patterns for sub-auroral ionospheres

Time delay and duration of ionospheric total electron content responses to geomagnetic disturbances

F2 region response to geomagnetic disturbances across Indian latitudes: O(1S) dayglow emission

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Resources

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F₂ region response to geomagnetic disturbances across Indian latitudes: O(¹S) dayglow emission