On the Occurrence of Afternoon Counter Electrojet Over Indian Longitudes During June Solstice in Solar Minimum

2018 ◽  
Author(s):  
Kuldeep Pandey ◽  
R. Sekar ◽  
B. G. Anandarao ◽  
S. P. Gupta ◽  
D. Chakrabarty
Keyword(s):  
Solar Minimum ◽  
Counter Electrojet ◽  
June Solstice

Spread F occurrence over a southern anomaly crest location in Brazil during June solstice of solar minimum activity

2011 ◽  
Vol 116 (A6) ◽  
pp. n/a-n/a ◽  
Author(s):  
C. M. N. Candido ◽  
I. S. Batista ◽  
F. Becker-Guedes ◽  
M. A. Abdu ◽  
J. H. A. Sobral ◽  
...  
Keyword(s):  
Solar Minimum ◽  
June Solstice ◽  
Spread F

scholarly journals Interhemispheric conjugate effect in longitude variations of mid-latitude ion density

2020 ◽  
Author(s):  
Yiding Chen ◽  
Libo Liu ◽  
Huijun Le ◽  
Hui Zhang
Keyword(s):  
Solar Minimum ◽  
Neutral Wind ◽  
Ion Density ◽  
Flux Tubes ◽  
The Earth ◽  
Defense Meteorological Satellite Program ◽  
June Solstice ◽  
Magnetic Flux Tubes ◽  
First Time ◽  
Meteorological Satellite

<p>Interhemispheric coupling between the northern and southern mid-lattitude ionosphere through the plasmasphere is difficult to confirm directly from observations. A possible result induced by this coupling is interhemispheric conjugacy of the mid-latitude ionosphere. In this paper, interhemispheric conjugate effect in longitude variations of mid-latitude total ion density (N<sub>i</sub>) is presented, for the first time, using the Defense Meteorological Satellite Program (DMSP) measurements; northern and southern N<sub>i</sub> longitude variations at 21:30 LT are similar between magnetically conjugate mid-latitudes around solar minimum June Solstice of 1996. The conjugate effect after sunset also occurs around the June Solstice in other solar minimum years but disappears when solar activity increases. We suggested that mid-latitude interhemispheric coupling is responsible for the conjugate effect. Neutral wind induced ionospheric transport causes topside longitude variations via upward diffusion at summer mid-latitudes; this further induces similar longitude variations of topside N<sub>i</sub> at winter mid-latitudes via the summer to winter interhemispheric coupling. The conjugate effect occurs only inside the plasmapause where magnetic flux tubes are closed and the plasma in these tubes can stably corotate with the Earth. The conjugate effect not only proves mid-latitude interhemispheric coupling through the plasmasphere, but also implies that neutral wind induced transport can affect ionospheric coupling to the plasmasphere at mid-latitudes.</p>

scholarly journals <i>Letter to the Editor</i>: Post-midnight onset of spread-F at Kodaikanal during the June solstice of solar minimum

1999 ◽  
Vol 17 (8) ◽  
pp. 1111-1115 ◽  
Author(s):  
J. H. Sastri
Keyword(s):  
Solar Activity ◽  
Solar Minimum ◽  
Equatorial Ionosphere ◽  
Instability Mechanism ◽  
Layer Height ◽  
Northern Summer ◽  
June Solstice ◽  
Spread F ◽  
Rayleigh Taylor Instability ◽  
Distinct Increase

Abstract. At dip equatorial stations in the Indian zone, spread-F conditions are known to develop preferentially around midnight during the June solstice (northern summer) months of low solar activity, in association with a distinct increase in F layer height. It is currently held that this onset of spread-F far away from the sunset terminator is due to the generalised Rayleigh-Taylor instability mechanism, with the gravitational and cross-field instability factors (and hence F layer height) playing important roles. We have studied the quarter-hourly ionograms of Kodaikanal (10.2°N; 77.5°E; dip 4°N) for the northern summer months (May-August) of 1994 and 1995 to ascertain the ambient ionospheric conditions against which the post-midnight onset of spread-F takes place. A data sample of 38 nights with midnight onset of spread-F and 34 nights without spread-F is used for the purpose. It is found that a conspicious increase in F layer height beginning around 2100 LT occurs on nights with spread-F as well as without spread-F. This feature is seen in the nocturnal pattern of F layer height on many individual nights as well as of average F layer height for the two categories of nights. The result strongly suggests that the F layer height does not play a pivotal role in the midnight onset of spread-F during the June solstice of solar minimum. The implications of this finding are discussed.Key words. Ionosphere (equatorial ionosphere; ionospheric irregularities)

scholarly journals Interhemispheric conjugate effect in longitude variations of mid-latitude ion density

2019 ◽  
Vol 9 ◽  
pp. A40
Author(s):  
Yiding Chen ◽  
Libo Liu ◽  
Huijun Le ◽  
Hui Zhang
Keyword(s):  
Solar Minimum ◽  
Neutral Wind ◽  
Ion Density ◽  
Flux Tubes ◽  
Defense Meteorological Satellite Program ◽  
June Solstice ◽  
Radar Measurements ◽  
Magnetic Flux Tubes ◽  
First Time ◽  
Meteorological Satellite

Earlier incoherent scatter radar measurements revealed upward topside ion fluxes in the summer and downward fluxes in the winter at mid-latitudes at night; a summer to winter interhemispheric coupling was accordingly inferred. However, this interhemispheric coupling through the plasmasphere is difficult to confirm directly from observations. A possible result induced by this coupling is interhemispheric conjugacy of the mid-latitude ionosphere. In this paper, interhemispheric conjugate effect in longitude variations of mid-latitude total ion density (Ni) is presented, for the first time, using the Defense Meteorological Satellite Program (DMSP) measurements; northern and southern Ni longitude variations at 21:30 LT are similar between magnetically conjugate mid-latitudes around solar minimum June Solstice of 1996. The conjugate effect after sunset also occurs around the June Solstice in other solar minimum years but disappears when solar activity increases. We suggested that mid-latitude interhemispheric coupling is responsible for the conjugate effect. Neutral wind induced ionospheric transport causes topside longitude variations via upward diffusion at summer mid-latitudes; this further induces similar longitude variations of topside Ni at winter mid-latitudes via the summer to winter interhemispheric coupling. The conjugate effect occurs only inside the plasmapause where magnetic flux tubes are closed and the plasma in these tubes can stably corotate with the Earth. The conjugate effect not only proves mid-latitude interhemispheric coupling through the plasmasphere, but also implies that neutral wind induced transport can affect ionospheric coupling to the plasmasphere at mid-latitudes.

On the pre-midnight ascent of F-layer in the June solstice during the deep solar minimum in 2008 over the Indian sector

2014 ◽  
Vol 121 ◽  
pp. 177-187 ◽  
Author(s):  
D. Chakrabarty ◽  
B.G. Fejer ◽  
S. Gurubaran ◽  
Tarun K. Pant ◽  
M.A. Abdu ◽  
...  
Keyword(s):  
Solar Minimum ◽  
June Solstice ◽  
Indian Sector

LONGITUDINAL EXTENT OF COUNTER ELECTROJET EVENTS

2018 ◽  
Vol 11 (3) ◽  
Author(s):  
V. V. Somayajulu ◽  
L. Cherian
Keyword(s):  
Counter Electrojet

Para solicitação de resumo, entrar em contato com editor-chefe ([email protected]). 

scholarly journals The River and the Sky: Astronomy and Topography in Caral Society, America's First Urban Centers

2021 ◽  
Vol 32 (1) ◽  
pp. 154-172
Author(s):  
A. César González-García ◽  
Aldemar Crispín ◽  
Ruth Shady Solís ◽  
José Ricra ◽  
Felipe Criado-Boado ◽  
...  
Keyword(s):  
Urban Centers ◽  
River Flooding ◽  
June Solstice

America's first urban centers may have been located in the Supe Valley, Peru. After investigating the location and the orientation of the main built structures, we show that it is not only the presence of the Supe River that determines their orientation but also that astronomical relationships within the orientation of the buildings dictate their setting within the valley. The southernmost position of moonrise on the horizon seems to be the most important astronomical target. There is the possibility of a trend toward attributing greater importance to the June solstice sunrise and the rising of certain stars or asterisms. These orientations could relate to specific moments throughout the year, in particular to seasonal rains, subsequent river flooding, and agricultural cycles. This is one of the earliest examples of the interaction of land- and skyscapes in human cultures and indeed the first in the Americas.

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