GEOMAGNETIC AND IONOSPHERIC OBSERVATIONS ASSOCIATED WITH AURORAL ACTIVITY DURING THE TOTAL SOLAR ECLIPSE OF JULY 20, 1963

1965 ◽  
Vol 43 (3) ◽  
pp. 457-462
Author(s):  
T. A. Clark ◽  
C. D. Anger
Keyword(s):  
Solar Eclipse ◽  
Noise Level ◽  
Total Solar Eclipse ◽  
Electron Precipitation ◽  
Moderate Degree ◽  
X Rays ◽  
Auroral Activity ◽  
Noise Absorption ◽  
Cosmic Noise ◽  
Auroral Luminosity

Data obtained at Fort Providence, N.W.T., Canada, during the total solar eclipse of July 20, 1963, indicate that during most of the partial eclipse there was a moderate degree of auroral activity. This activity became slight during the period of totality and no auroral luminosity was detected. Electron precipitation was indicated by an enhancement of the intensity of X rays of energy greater than 9 keV at balloon altitudes and by small amounts of cosmic-noise absorption. A small but irregular increase in cosmic-noise level at 30 Mc/s, which was greater than 0.2 dB at totality, was recorded. It was concluded that the irregularity was caused by small amounts of superimposed auroral absorption.

ABSORPTION MEASUREMENTS DURING THE SOLAR ECLIPSE OF JULY 20, 1963

1964 ◽  
Vol 42 (7) ◽  
pp. 1382-1386 ◽  
Author(s):  
E. L. Vogan
Keyword(s):  
Solar Eclipse ◽  
Noise Level ◽  
Total Solar Eclipse ◽  
Cosmic Noise ◽  
Absorption Measurements

Riometer data obtained from several Canadian stations during the total solar eclipse of July 20, 1963, are presented and discussed. A small increase in cosmic noise level, amounting to about 0.25 dB at 30 Mc/s, was observed at Ottawa, Cape Jones, and Churchill.

scholarly journals Cosmic noise absorption signature of particle precipitation during ICME sheaths and ejecta

2019 ◽  
Author(s):  
Emilia Kilpua ◽  
Liisa Juusola ◽  
Maxime Grandin ◽  
Antti Kero ◽  
Stepan Dubyagin ◽  
...  
Keyword(s):  
Radiation Belt ◽  
Geomagnetic Latitude ◽  
Electron Precipitation ◽  
Occurrence Frequency ◽  
Ulf Waves ◽  
Interplanetary Coronal Mass Ejections ◽  
Noise Absorption ◽  
Radiation Belt Electrons ◽  
Cosmic Noise ◽  
Trapped Radiation

Abstract. We study here energetic (E > 30 keV) electron precipitation using cosmic noise absorption (CNA) during the sheath and ejecta structures of 61 interplanetary coronal mass ejections (ICMEs) observed in the near-Earth solar wind between 1997 and 2012. The data comes from the Finnish riometer chain from stations extending from auroral (IVA, 65.2 geomagnetic latitude, MLAT) to subauroral (JYV, 59.0 MLAT) latitudes. We find that sheaths and ejecta lead frequently to enhanced CNA (> 0.5 dB) both at auroral and subauroral latitudes, although the CNA magnitudes stay relatively low (medians around 1 dB). Due to their longer duration, ejecta typically lead to more sustained enhanced CNA periods (on average 6–7 hours), but the sheaths and ejecta were found to be equally effective in inducing enhanced CNA when relative occurrence frequency and CNA magnitude were considered. Only at the lowest MLAT station JYV ejecta were more effective in causing enhanced CNA. Some clear magnetic local time (MLT) trends and differences between the ejecta and sheath were found. The occurrence frequency and magnitude of CNA activity was lowest close to midnight, while it peaked for the sheaths in the morning and afternoon/evening sectors and for the ejecta in the morning and noon sectors. These differences may reflect differences in typical MLT distributions of wave modes that precipitate substorm-injected and trapped radiation belt electrons during the sheath and ejecta. Our study also emphasizes the importance of substorms and magnetospheric ULF waves for enhanced CNA.

scholarly journals Observations of the spatial structure of electron precipitation pulsations using an imaging riometer

2003 ◽  
Vol 21 (4) ◽  
pp. 997-1003 ◽  
Author(s):  
A. Senior ◽  
F. Honary
Keyword(s):  
Spatial Structure ◽  
Spatial Variation ◽  
Phase Relationship ◽  
Electron Precipitation ◽  
Mhd Waves ◽  
Noise Absorption ◽  
Fixed Phase ◽  
Mhd Waves And Instabilities ◽  
Pulsation Activity ◽  
Cosmic Noise

Abstract. Electron precipitation can be modulated by geomagnetic pulsation activity. This can be observed as pulsation of cosmic noise absorption as measured by riometers. Observations of such pulsations exhibiting field-line resonance and particle-driven characteristics using an imaging riometer are presented and the capability of the instrument to map their spatial structure is demonstrated. It is shown that for the events studied, the spatial variation of pulsation phase as measured by the riometer agrees with that inferred from ground-based magnetometers, whereas the spatial variation of pulsation amplitude may show a different structure. It is suggested that this is consistent with the mechanism proposed by Coroniti and Kennel (1970) where one would expect a fixed phase relationship between magnetic and absorption pulsations, but where the amplitude of the absorption pulsation can depend on several factors other than the amplitude of the magnetic pulsation.Key words. Ionosphere (ionosphere–magnetosphere interactions; particle precipitation) – Magnetospheric physics (MHD waves and instabilities)

scholarly journals Energetic electron precipitation during sawtooth injections

2007 ◽  
Vol 25 (5) ◽  
pp. 1199-1214 ◽  
Author(s):  
A. J. Kavanagh ◽  
G. Lu ◽  
E. F. Donovan ◽  
G. D. Reeves ◽  
F. Honary ◽  
...  
Keyword(s):  
National Laboratory ◽  
Energetic Electron ◽  
Electron Precipitation ◽  
Optical Observations ◽  
Cosmic Radio ◽  
Magnetospheric Substorms ◽  
Los Alamos National Laboratory ◽  
Sustained Activity ◽  
Noise Absorption ◽  
Cosmic Noise

Abstract. We present simultaneous riometer observations of cosmic noise absorption in the nightside and dawn-noon sectors during sawtooth particle injections during 18 April 2002. Energetic electron precipitation (>30 keV) is a feature of magnetospheric substorms and cosmic radio noise absorption acts as a proxy for qualitatively measuring this precipitation. This event provides an opportunity to compare the absorption that accompanies periodic electron injections with the accepted paradigm of substorm-related absorption. We consider whether the absorption is consistent with the premise that these injections are quasi-periodic substorms and study the effects of sustained activity on the level of precipitation. Four consecutive electron injection events have been identified from the LANL (Los Alamos National Laboratory) geosynchronous data; the first two showing that additional activity can occur within the 2–4 h sawtooth periodicity. The first three events have accompanying absorption on the nightside that demonstrate good agreement with the expected pattern of substorm-absorption: discrete spike events with poleward motion at the onset followed by equatorward moving structures and more diffuse absorption, correlated with optical observations. Dayside absorption is linked to gradient-curvature drifting electrons observed at geostationary orbit and it is shown that low fluxes can lead to a lack of absorption as precipitation is suppressed; precipitation begins when the drifting electron flux surpasses some critical level following continuous injections of electrons from the magnetotail. In addition it is shown that the apparent motion of absorption determined from an azimuthal chain of riometers exhibits an acceleration that may be indicative of an energisation of the drifting electron population.

Very High Resolution Analysis of the Dynamics of a Coronal Plasmoid

1994 ◽  
Vol 144 ◽  
pp. 593-596
Author(s):  
O. Bouchard ◽  
S. Koutchmy ◽  
L. November ◽  
J.-C. Vial ◽  
J. B. Zirker
Keyword(s):  
High Resolution ◽  
Solar Eclipse ◽  
Total Solar Eclipse ◽  
Field Of View ◽  
Small Field ◽  
High Resolution Analysis ◽  
Ccd Observations ◽  
Resolution Analysis ◽  
Very High ◽  
Small Field Of View

AbstractWe present the results of the analysis of a movie taken over a small field of view in the intermediate corona at a spatial resolution of 0.5“, a temporal resolution of 1 s and a spectral passband of 7 nm. These CCD observations were made at the prime focus of the 3.6 m aperture CFHT telescope during the 1991 total solar eclipse.

FeXIV Line Emission Polarization of the July 11, 1991 Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 541-547
Author(s):  
J. Sýkora ◽  
J. Rybák ◽  
P. Ambrož
Keyword(s):  
High Resolution ◽  
Solar Corona ◽  
Emission Line ◽  
Solar Eclipse ◽  
White Light ◽  
Preliminary Analysis ◽  
Line Emission ◽  
Total Solar Eclipse ◽  
Degree Of Polarization ◽  
High Resolution Images

AbstractHigh resolution images, obtained during July 11, 1991 total solar eclipse, allowed us to estimate the degree of solar corona polarization in the light of FeXIV 530.3 nm emission line and in the white light, as well. Very preliminary analysis reveals remarkable differences in the degree of polarization for both sets of data, particularly as for level of polarization and its distribution around the Sun’s limb.

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