scholarly journals Relationship between the Northern Hemisphere Joule heating and geomagnetic activity in the southern polar cap

2000 ◽  
Vol 105 (A12) ◽  
pp. 27167-27177 ◽  
Author(s):  
P. Ballatore ◽  
L. J. Lanzerotti ◽  
G. Lu ◽  
D. J. Knipp
Keyword(s):  
Northern Hemisphere ◽  
Geomagnetic Activity ◽  
Joule Heating ◽  
Polar Cap

Solar and Geomagnetic Activity Impact on Occurrence and Spatial Size of Cold and Hot Polar Cap Patches

2021 ◽  
Author(s):  
Duan Zhang ◽  
Qing He Zhang ◽  
Y. Z. Ma ◽  
Kjellmar Oksavik ◽  
L. R. Lyons ◽  
...  
Keyword(s):  
Geomagnetic Activity ◽  
Polar Cap ◽  
Spatial Size

scholarly journals Northern Hemisphere patterns of phase coherence between solar/geomagnetic activity and NCEP/NCAR and ERA40 near-surface air temperature in period 7–8 years oscillatory modes

2011 ◽  
Vol 18 (2) ◽  
pp. 251-260 ◽  
Author(s):  
M. Paluš ◽  
D. Novotná
Keyword(s):  
Northern Hemisphere ◽  
Air Temperature ◽  
Geomagnetic Activity ◽  
North Atlantic ◽  
Surface Air Temperature ◽  
Phase Coherence ◽  
Near Surface ◽  
Monthly Data ◽  
Nao Index ◽  
Aa Index

Abstract. Beginning from the 1950's, Paluš and Novotná (2009) observed statistically significant phase coherence among oscillatory modes with the period of approximately 7–8 years detected in monthly time series of sunspot numbers, geomagnetic activity aa index, North Atlantic Oscillation (NAO) index and near-surface air temperature from several mid-latitude European stations. Focusing on geographical distribution of the phenomenon we study Northern Hemisphere patterns of phase coherence between solar/geomagnetic activity and NCEP/NCAR and ERA40 near-surface air temperature. Both the reanalysis datasets provide consistent patterns of areas with marked phase coupling between solar/geomagnetic activity and climate variability observed in continuous monthly data, independent of the season, however, confined to the temporal scale related to the oscillatory periods about 7–8 years.

scholarly journals Simultaneous tracking of reconnected flux tubes: Cluster and conjugate SuperDARN observations on 1 April 2004

2008 ◽  
Vol 26 (6) ◽  
pp. 1545-1557 ◽  
Author(s):  
Q.-H. Zhang ◽  
R. Y. Liu ◽  
M. W. Dunlop ◽  
J. Y. Huang ◽  
H. Q. Hu ◽  
...  
Keyword(s):  
Response Time ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Large Scale ◽  
Global Flow ◽  
Local Response ◽  
Polar Cap ◽  
Flux Tubes ◽  
North West ◽  
The Third

Abstract. While the Cluster spacecraft were located near the high-latitude magnetopause, between 11:30–13:00 UT on 1 April 2004, a series of medium to large scale (40 nT, 0.6–1.2 Re) FTEs were observed. During this pass, simultaneous and conjugated SuperDARN measurements are available that show a global flow pattern which is consistent with the expected (mapped) north-west motion of (predominantly sub-solar) reconnected, magnetic flux at the magnetopause. We focus on analysing the local response of three FTEs, tracking their magnetopause motion via the four-spacecraft measurements together with their corresponding ground mapped motions. For two of these FTEs, where the tracking is strongly coordinated with the ionospheric flow at each footprint of the implied flux tubes in the Northern Hemisphere, conditions corresponded to stable, increasing (>100°) clock angle, while the third event, where the correspondence is less strong, coincided with low (<100°) clock angle. Flux tube motion, both measured and modeled from the inferred X-line, qualitatively matches the clear velocity enhancements in ionospheric convections with northward and westward flow at each location in the Northern Hemisphere, measured simultaneously by SuperDARN, and also roughly matches the observed, south-eastward ionospheric flow in the Southern Hemisphere at the time of these events. The time periods of these velocity enhancements infer that the evolution time of the FTEs is about 4–6 min from its origin on magnetopause to its addition to the polar cap. However, the ionospheric response time in the Southern Hemisphere might be 2 min longer for the 12:31 UT FTE (and 6 min longer for the 12:51 UT FTE) than the response time in the Northern Hemisphere.

scholarly journals The importance of solar illumination for discrete and diffuse aurora

2005 ◽  
Vol 23 (11) ◽  
pp. 3481-3486 ◽  
Author(s):  
M. Hamrin ◽  
P. Norqvist ◽  
K. Rönnmark ◽  
D. Fellgård
Keyword(s):  
Northern Hemisphere ◽  
Geomagnetic Activity ◽  
Seasonal Variations ◽  
Pitch Angle ◽  
Seasonal Effects ◽  
Comprehensive Overview ◽  
Diffuse Aurora

Abstract. We present a comprehensive overview of the occurrence of discrete and diffuse aurora in the nightside Northern Hemisphere at invariant latitudes 55°-75°. Twenty-one months of Freja observations (1 January 1993 to 30 September 1994) from the Northern Hemisphere, obtained at altitude, are included in this investigation. We investigate the importance of seasonal effects, solar illumination and geomagnetic activity for the auroral precipitation. The seasonal variations in the occurrence of discrete aurora are separated from the dependence on solar illumination of the ionosphere. When the effects of sunlight are eliminated, aurora is found to be more common during the summer. The occurrence of diffuse, as well as discrete aurora, is suppressed by solar illumination of the ionosphere. This dependence of diffuse auroral precipitation on ionospheric conditions is not predicted by theories that attribute diffuse aurora to equatorial pitch-angle diffusion of hot magnetospheric electrons.

Polar-glow aurora observed from Spitsbergen

Polar Record ◽  
1995 ◽  
Vol 31 (178) ◽  
pp. 315-326 ◽  
Author(s):  
D. A. R. Simmons ◽  
K. Henriksen
Keyword(s):  
Solar Activity ◽  
Geomagnetic Activity ◽  
Cosmic Ray ◽  
High Energy ◽  
Auroral Ionosphere ◽  
Diffuse Type ◽  
Polar Cap ◽  
Auroral Activity

AbstractPolar-glow aurora is a diffuse type of polar-cap event that follows bombardment of the auroral ionosphere with high-energy protons from ‘cosmic ray’ flares at times of great solar and geomagnetic activity. Observations of five polar glows are presented together with details of the circumstances surrounding their occurrence. The first three glows were associated with enhanced solar activity between 3 and 15 February 1986 and the fourth and fifth glows with enhanced solar activity between 3 December 1993 and 10 February 1994. Despite the fact that the flares associated with the latter solar outburst were much smaller than those associated with the former, both periods of solar activity showed equally marked geophysical, geomagnetic, and auroral activity.

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