50 MHz Backscatter Observations in the Polar Cap Ionospheric E Region

1989 ◽  
pp. 435-447 ◽  
Author(s):  
C. Haldoupis ◽  
M. J. McKibben ◽  
J. A. Koehler ◽  
G. J. Sofko
Keyword(s):  
Polar Cap ◽  
E Region

scholarly journals EISCAT Svalbard radar observations of SPEAR-induced E- and F-region spectral enhancements in the polar cap ionosphere

2007 ◽  
Vol 25 (8) ◽  
pp. 1801-1814 ◽  
Author(s):  
R. S. Dhillon ◽  
T. R. Robinson ◽  
T. K. Yeoman
Keyword(s):  
High Power ◽  
Polar Cap ◽  
Incoherent Scatter ◽  
F Region ◽  
Sporadic E Layers ◽  
First Results ◽  
Plasma Line ◽  
E Region ◽  
Sporadic E ◽  
Overdense Plasma

Abstract. The Space Plasma Exploration by Active Radar (SPEAR) facility has successfully operated in the high-power heater and low-power radar modes and has returned its first results. The high-power results include observations of SPEAR-induced ion and plasma line spectral enhancements recorded by the EISCAT Svalbard UHF incoherent scatter radar system (ESR), which is collocated with SPEAR. These SPEAR-enhanced spectra possess features that are consistent with excitation of both the purely growing mode and the parametric decay instability. In this paper, we present observations of upper and lower E-region SPEAR-induced ion and plasma line enhancements, together with F-region spectral enhancements, which indicate excitation of both instabilities and which are consistent with previous theoretical treatments of instability excitation in sporadic E-layers. In agreement with previous observations, spectra from the lower E-region have the single-peaked form characteristic of collisional plasma. Our observations of the SPEAR-enhanced E-region spectra suggest the presence of variable drifting regions of patchy overdense plasma, which is a finding also consistent with previous results.

Rocket-borne wave, field, and plasma observations in unstable polar cap E-region

1976 ◽  
Vol 3 (7) ◽  
pp. 399-402 ◽  
Author(s):  
J. K. Olesen ◽  
F. Primdahl ◽  
F. Spangslev ◽  
E. Ungstrup ◽  
Bahnsen ◽  
...  
Keyword(s):  
Wave Field ◽  
Polar Cap ◽  
E Region

scholarly journals A Case Study of Polar Cap Sporadic-E Layer Associated with TEC Variations

2021 ◽  
Vol 13 (7) ◽  
pp. 1324
Author(s):  
Yong Wang ◽  
Periyadan T. Jayachandran ◽  
David R. Themens ◽  
Anthony M. McCaffrey ◽  
Qing-He Zhang ◽  
...  
Keyword(s):  
Electron Content ◽  
High Electron ◽  
Gps Receiver ◽  
Polar Cap ◽  
Total Electron ◽  
Multiple Measurements ◽  
E Region ◽  
Sporadic E Layer ◽  
Sporadic E

The Sporadic-E (Es) layer is an often-observed phenomenon at high latitudes; however, our understanding of the polar cap Es layer is severely limited due to the scarce number of measurements. Here, the first comprehensive study of the polar cap Es layer associated with Global Positioning System (GPS) Total Electron Content (TEC) variations and scintillations is presented with multiple measurements at Resolute, Canada (Canadian Advanced Digital Ionosonde (CADI), Northward-looking face of Resolute Incoherent-Scatter Radar (RISR-N), and GPS receiver). According to the joint observations, the polar cap Es layer is a thin patch structure with variously high electron density, which gradually develops into the lower E region (~100 km) and horizontally extends >200 km. Moreover, the TEC variations produced by the polar cap Es layer are pulse-like enhancements with a general amplitude of ~0.5 TECu and are followed by smaller but rapid TEC perturbations. Furthermore, the possible scintillation effects likely associated with the polar cap Es layer are also discussed. As a consequence, the results widely expand our understanding on the polar cap Es layer, in particular on TEC variations.

Doppler radio observations of 3-meter irregularities in the polar cap E region

1987 ◽  
Vol 92 (A2) ◽  
pp. 1271 ◽  
Author(s):  
G. J. Sofko ◽  
J. A. Koehler ◽  
C. Haldoupis ◽  
M. J. McKibben ◽  
A. G. McNamara
Keyword(s):  
Polar Cap ◽  
Radio Observations ◽  
E Region

scholarly journals Ion and neutral temperature distributions in the E-region observed by the EISCAT Tromsø and Svalbard radars

2002 ◽  
Vol 20 (9) ◽  
pp. 1415-1427 ◽  
Author(s):  
S. Maeda ◽  
S. Nozawa ◽  
M. Sugino ◽  
H. Fujiwara ◽  
M. Suzuki
Keyword(s):  
Heat Transport ◽  
Frictional Heating ◽  
Soft Particle ◽  
Ion Temperature ◽  
Polar Cap ◽  
Low Latitude ◽  
Neutral Temperature ◽  
Defense Meteorological Satellite Program ◽  
E Region ◽  
Uhf Radar

Abstract. Simultaneous Common Program Two experiments by the EISCAT UHF radar at Tromsø and the EISCAT Svalbard radar at Longyearbyen from 00:00 to 15:00 UT on 22 September 1998 and 9 March 1999 have been utilized to investigate distributions of the ion and neutral temperatures in the E-region between 105 and 115 km. During the experiments, soft particle precipitations in the dayside cusp were observed over the Svalbard radar site by the Defense Meteorological Satellite Program (DMSP) F11 satellite. It is found that the dayside electric field in the regions of the low-latitude boundary of the polar cap and the cusp was greater and more variable than that in the auroral region. The ion temperature, parallel to the geomagnetic field at Longyearbyen, was higher than that at Tromsø during the daytime from 06:00 to 12:00 UT. The steady-state ion energy equation has been applied to derive neutral temperature under the assumption of no significant heat transport and viscous heating. The estimated neutral temperature at Longyearbyen was also higher than that at Tromsø. The ion and neutral energy budget was discussed in terms of the ion frictional heating and the Joule heating. The results indicate two possibilities: either the neutral temperature was high in the low latitude boundary of the polar cap and the cusp, or the heat transport by the polar cap neutral winds toward the dayside sector was significant.Key words. Ionosphere (auroral ionosphere; ionosphere–atmosphere interactions; polar ionosphere)

Rocket-borne wave, field, and plasma observations in unstable polar cap E-region

1976 ◽  
Vol 3 (12) ◽  
pp. 711-714 ◽  
Author(s):  
J. K. Olesen ◽  
F. Primdahl ◽  
F. Spangslev ◽  
E. Ungstrup ◽  
A. Bahnsen ◽  
...  
Keyword(s):  
Wave Field ◽  
Polar Cap ◽  
E Region

A large rotating structure around AB Doradus A at VLBI scale

2019 ◽  
Vol 15 (S354) ◽  
pp. 189-194
Author(s):  
J. B. Climent ◽  
J. C. Guirado ◽  
R. Azulay ◽  
J. M. Marcaide
Keyword(s):  
Magnetic Reconnection ◽  
Main Sequence ◽  
Complex Structure ◽  
Main Sequence Star ◽  
Polar Cap ◽  
Vlbi Observations ◽  
Rotating Structure ◽  
Source Structure ◽  
Expected Position

AbstractWe report the results of three VLBI observations of the pre-main-sequence star AB Doradus A at 8.4 GHz. With almost three years between consecutive observations, we found a complex structure at the expected position of this star for all epochs. Maps at epochs 2007 and 2010 show a double core-halo morphology while the 2013 map reveals three emission peaks with separations between 5 and 18 stellar radii. Furthermore, all maps show a clear variation of the source structure within the observing time. We consider a number of hypothesis in order to explain such observations, mainly: magnetic reconnection in loops on the polar cap, a more general loop scenario and a close companion to AB Dor A.

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