About the nature of the Night-time Winter Anomaly effect (NWA) in the F-region of the ionosphere

1995 ◽  
Vol 43 (5) ◽  
pp. 603-612 ◽  
Author(s):  
N. Jakowski ◽  
M. Förster
Keyword(s):  
Night Time ◽  
F Region ◽  
Winter Anomaly

scholarly journals Observations of AGW/TID propagation across the polar cap: a case study

2011 ◽  
Vol 29 (8) ◽  
pp. 1355-1363 ◽  
Author(s):  
H. T. Cai ◽  
F. Yin ◽  
S. Y. Ma ◽  
I. W. McCrea
Keyword(s):  
Large Scale ◽  
Source Region ◽  
Polar Cap ◽  
Night Time ◽  
F Region ◽  
Atmospheric Disturbances ◽  
Geomagnetic Pole ◽  
Ionization Waves ◽  
North Polar ◽  
Propagation Properties

Abstract. In this paper, we present observational evidence for the trans-polar propagation of large-scale Traveling Ionospheric Disturbances (TIDs) from their nightside source region to the dayside. On 13 February 2001, the 32 m dish of EISCAT Svalbard Radar (ESR) was directing toward the geomagnetic pole at low elevation (30°) during the interval 06:00–12:00 UT (MLT ≈ UT + 3 h), providing an excellent opportunity to monitor the ionosphere F-region over the polar cap. The TIDs were first detected by the ESR over the dayside north polar cap, propagating equatorward, and were subsequently seen by the mainland UHF radar at auroral latitudes around geomagnetic local noon. The propagation properties of the observed ionization waves suggest the presence of a moderately large-scale TIDs, propagating across the northern polar cap from the night-time auroral source during substorm conditions. Our results agree with the theoretical simulations by Balthazor and Moffett (1999) in which poleward-propagating large-scale traveling atmospheric disturbances were found to be self-consistently driven by enhancements in auroral heating.

A measurement of positive ion density in the night-time F-region

1965 ◽  
Vol 13 (1) ◽  
pp. 1-8 ◽  
Author(s):  
K. Norman ◽  
A.P. Willmore
Keyword(s):  
Night Time ◽  
Ion Density ◽  
F Region ◽  
Positive Ion

Photoionization rates in the night-time E- and F-region ionosphere∗

1980 ◽  
Vol 28 (11) ◽  
pp. 1027-1033 ◽  
Author(s):  
D.F. Strobel ◽  
C.B. Opal ◽  
R.R. Meier
Keyword(s):  
Night Time ◽  
F Region

Causes of the F region winter anomaly

1980 ◽  
Vol 7 (5) ◽  
pp. 301-304 ◽  
Author(s):  
D. G. Torr ◽  
M. R. Torr ◽  
P. G. Richards
Keyword(s):  
F Region ◽  
Winter Anomaly

scholarly journals Equatorial night-time F-region zonal electric fields

1995 ◽  
Vol 13 (8) ◽  
pp. 871-878 ◽  
Author(s):  
S. S. Hari ◽  
B. V. Krishna Murthy
Keyword(s):  
Seasonal Variation ◽  
Electric Field ◽  
Electric Fields ◽  
Night Time ◽  
Equatorial Station ◽  
F Region ◽  
Vertical Drift ◽  
Longitudinal Gradients ◽  
Cycle Maximum ◽  
E Region

Abstract. Night-time F-region vertical electrodynamic drifts at the magnetic equatorial station, Trivandrum are obtained for a period of 2 years, 1989 and 1990 (corresponding to solar cycle maximum epoch), using ionosonde h'F data. The seasonal variation of the vertical drift is found to be associated with the longitudinal gradients of the thermospheric zonal wind. Further, the seasonal variation of the prereversal enhancement of the vertical drift is associated with the time difference between the sunset times of the conjugate E-regions (magnetic field line linked to F-region) which is indicative of the longitudinal gradients of the conductivity (of the E-region). The vertical drifts and the causative zonal electric fields at Trivandrum are compared with those at Jicamarca and F-region zonal electric field models. It is seen that the night-time downward drift (as also the causative westward electric field) at Jicamarca is greater than that at Trivandrum. The prereversal enhancement of the drift is greater at Jicamarca than at Trivandrum during the summer and the equinoxes, whereas during the winter the opposite is the case.

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