scholarly journals Low latitude thermospheric responses to magnetic storms

2013 ◽  
Vol 118 (6) ◽  
pp. 3866-3876 ◽  
Author(s):  
G. D. Earle ◽  
R. L. Davidson ◽  
R. A. Heelis ◽  
W. R. Coley ◽  
D. R. Weimer ◽  
...  
Keyword(s):  
Magnetic Storms ◽  
Low Latitude

A study of low-latitude VHF scintillations in relation to electric fields during magnetic storms

Radio Science ◽  
1993 ◽  
Vol 28 (3) ◽  
pp. 389-400 ◽  
Author(s):  
D. R. Lakshmi ◽  
R. S. Dabas ◽  
B. C. N. Rao ◽  
B. M. Reddy
Keyword(s):  
Electric Fields ◽  
Magnetic Storms ◽  
Low Latitude

scholarly journals Low-Latitude Auroras Observed at Moshiri and Rikubetsu (L=1.6) during Magnetic Storms on February 26, 27, 29, and May 10, 1992.

1994 ◽  
Vol 46 (3) ◽  
pp. 231-252 ◽  
Author(s):  
K. Shiokawa ◽  
K. Yumoto ◽  
Y. Tanaka ◽  
T. Oguti ◽  
Y. Kiyama
Keyword(s):  
Magnetic Storms ◽  
Low Latitude

scholarly journals Prediction of geomagnetically induced currents (GICs) flowing in Japanese power grid for Carrington-class magnetic storms

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Yusuke Ebihara ◽  
Shinichi Watari ◽  
Sandeep Kumar
Keyword(s):  
Transmission Lines ◽  
Power Grid ◽  
Magnetic Storms ◽  
Power Grids ◽  
Geomagnetically Induced Currents ◽  
Geomagnetic Disturbances ◽  
Low Latitude ◽  
Solar Eruptions ◽  
Induced Currents ◽  
Extra High Voltage

AbstractLarge-amplitude geomagnetically induced currents (GICs) are the natural consequences of the solar–terrestrial connection triggered by solar eruptions. The threat of severe damage of power grids due to the GICs is a major concern, in particular, at high latitudes, but is not well understood as for low-latitude power grids. The purpose of this study is to evaluate the lower limit of the GICs that could flow in the Japanese power grid against a Carrington-class severe magnetic storm. On the basis of the geomagnetic disturbances (GMDs) observed at Colaba, India, during the Carrington event in 1859, we calculated the geoelectric disturbances (GEDs) by a convolution theory, and calculated GICs flowing through transformers at 3 substations in the Japanese extra-high-voltage (500-kV) power grid by a linear combination of the GEDs. The estimated GEDs could reach ~ 2.5 V/km at Kakioka, and the GICs could reach, at least, 89 ± 30 A near the storm maximum. These values are several times larger than those estimated for the 13–14 March 1989 storm (in which power blackout occurred in Canada), and the 29–31 October 2003 storm (in which power blackout occurred in Sweden). The GICs estimated here are the lower limits, and there is a probability of stronger GICs at other substations. The method introduced here will be immediately applicable for benchmark evaluation of low-latitude GICs against the Carrington-class magnetic storms if one assumes electrical parameters, such as resistance of transmission lines, with sufficient accuracy.

scholarly journals Sporadic Aurora near Geomagnetic Equator: In the Philippines, on 27 October 1856

2018 ◽  
Author(s):  
Hisashi Hayakawa ◽  
José M. Vaquero ◽  
Yusuke Ebihara
Keyword(s):  
Magnetic Activity ◽  
The Philippines ◽  
Magnetic Storms ◽  
Geomagnetic Equator ◽  
Physical Explanation ◽  
Low Latitude ◽  
Magnetic Latitude ◽  
Considerable Size

Abstract. While low latitude auroral displays are normally considered to be a manifestation of magnetic storms of considerable size, Silverman (2003, JGR, 108, A4) reported numerous sporadic auroras which appear locally at relatively low magnetic latitudes during times of just moderate magnetic activity. Here, a case study is presented of an aurora near the geomagnetic equator based on a report from the Philippine Islands on 27 October 1856. An analysis of this report shows it to be consistent with the known cases of sporadic aurorae except for its considerably low magnetic latitude. The record also suggests that extremely low-latitude aurora is not always accompanied with large magnetic storms. The description of its brief appearance leads to a possible physical explanation based on an ephemeral magnetospheric disturbance provoking this sporadic aurora.

scholarly journals Sporadic auroras near the geomagnetic equator: in the Philippines, on 27 October 1856

2018 ◽  
Vol 36 (4) ◽  
pp. 1153-1160 ◽  
Author(s):  
Hisashi Hayakawa ◽  
José M. Vaquero ◽  
Yusuke Ebihara
Keyword(s):  
Magnetic Activity ◽  
The Philippines ◽  
Magnetic Storms ◽  
Geomagnetic Equator ◽  
Physical Explanation ◽  
Low Latitude ◽  
Magnetic Latitude ◽  
Considerable Size

Abstract. While low-latitude auroral displays are normally considered to be a manifestation of magnetic storms of considerable size, Silverman (2003, JGR, 108, A4) reported numerous “sporadic auroras” which appear locally at relatively low magnetic latitude during times of just moderate magnetic activity. Here, a case study is presented of an aurora near the geomagnetic equator based on a report from the Philippine islands on 27 October 1856. An analysis of this report shows it to be consistent with the known cases of sporadic auroras, except for its appearance at considerably low magnetic latitude. The record also suggests that an extremely low-latitude aurora is not always accompanied by large magnetic storms. The description of its brief appearance leads to a possible physical explanation based on an ephemeral magnetospheric disturbance provoking this sporadic aurora.

scholarly journals Sudden post-midnight decrease in equatorial F-region electron densities associated with severe magnetic storms

1997 ◽  
Vol 15 (3) ◽  
pp. 306-313 ◽  
Author(s):  
D. R. Lakshmi ◽  
B. Veenadhari ◽  
R. S. Dabas ◽  
B. M. Reddy
Keyword(s):  
Electric Fields ◽  
Magnetic Storms ◽  
Equatorial Region ◽  
Electron Densities ◽  
Low Latitude ◽  
General Behaviour ◽  
F Region ◽  
Short Period ◽  
Electric Field Direction ◽  
Meridional Winds

Abstract. A detailed analysis of the responses of the equatorial ionosphere to a large number of severe magnetic storms shows the rapid and remarkable collapse of F-region ionisation during post-midnight hours; this is at variance with the presently accepted general behaviour of the low-latitude ionosphere during magnetic storms. This paper discusses such responses as seen in the ionosonde data at Kodaikanal (Geomagn. Lat. 0.6 N). It is also observed that during magnetic storm periods the usual increase seen in the h'F at Kodaikanal during sunset hours is considerably suppressed and these periods are also characterised by increased foF2 values. It is suggested that the primary process responsible for these dramatic pre- and post-midnight changes in foF2 during magnetic storms could be due to changes in the magnitude as well as in the direction of usual equatorial electric fields. During the post-midnight periods the change in electric-field direction from westward to eastward for a short period causes an upward E × B plasma drift resulting in increased h'F and decreased electron densities in the equatorial region. In addition, it is also suggested that the enhanced storm-induced meridional winds in the thermosphere, from the poles towards the equator, may also cause the decreases in electron density seen during post-midnight hours by spatially transporting the F-region ionisation southwards away from Kodaikanal. The paper also includes a discussion on the effects of such decreases in ionisation on low-latitude HF communications.

scholarly journals Ground and satellite observations of low-latitude red auroras at the initial phase of magnetic storms

2013 ◽  
Vol 118 (1) ◽  
pp. 256-270 ◽  
Author(s):  
K. Shiokawa ◽  
Y. Miyoshi ◽  
P. C. Brandt ◽  
D. S. Evans ◽  
H. U. Frey ◽  
...  
Keyword(s):  
Initial Phase ◽  
Magnetic Storms ◽  
Satellite Observations ◽  
Low Latitude
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