Seasonal and solar activity dependence of the generalized polar wind with low-altitude auroral ion energization

2003 ◽  
Vol 108 (A11) ◽  
Author(s):  
A. R. Barakat
Keyword(s):  
Solar Activity ◽  
Polar Wind ◽  
Ion Energization ◽  
Low Altitude ◽  
Activity Dependence

On the solar activity dependence of midnight equatorial plasma bubbles during June solstice periods

2021 ◽  
Vol 5 (4) ◽  
pp. 1-9
Author(s):  
K. K. Ajith ◽  
◽  
S. Tulasi Ram ◽  
GuoZhu Li ◽  
M. Yamamoto ◽  
...  
Keyword(s):  
Solar Activity ◽  
Plasma Bubbles ◽  
Equatorial Plasma Bubbles ◽  
June Solstice ◽  
Activity Dependence

scholarly journals Alfvénic fluctuations in "newborn"' polar solar wind

2005 ◽  
Vol 23 (4) ◽  
pp. 1513-1520 ◽  
Author(s):  
B. Bavassano ◽  
E. Pietropaolo ◽  
R. Bruno
Keyword(s):  
Solar Wind ◽  
Solar Activity ◽  
Solar Maximum ◽  
Activity Cycle ◽  
Residual Energy ◽  
Mhd Waves ◽  
Polar Wind ◽  
Interplanetary Physics ◽  
Low Latitudes ◽  
Comparative Statistical Analysis

Abstract. The 3-D structure of the solar wind is strongly dependent upon the Sun's activity cycle. At low solar activity a bimodal structure is dominant, with a fast and uniform flow at the high latitudes, and slow and variable flows at low latitudes. Around solar maximum, in sharp contrast, variable flows are observed at all latitudes. This last kind of pattern, however, is a relatively short-lived feature, and quite soon after solar maximum the polar wind tends to regain its role. The plasma parameter distributions for these newborn polar flows appear very similar to those typically observed in polar wind at low solar activity. The point addressed here is about polar wind fluctuations. As is well known, the low-solar-activity polar wind is characterized by a strong flow of Alfvénic fluctuations. Does this hold for the new polar flows too? An answer to this question is given here through a comparative statistical analysis on parameters such as total energy, cross helicity, and residual energy, that are of general use to describe the Alfvénic character of fluctuations. Our results indicate that the main features of the Alfvénic fluctuations observed in low-solar-activity polar wind have been quickly recovered in the new polar flows developed shortly after solar maximum. Keywords. Interplanetary physics (MHD waves and turbulence; Sources of the solar wind) – Space plasma physics (Turbulence)

The behaviour of measured SEU at low altitude during periods of high solar activity (spacecraft memories)

1990 ◽  
Vol 37 (6) ◽  
pp. 1938-1946 ◽  
Author(s):  
R. Harboe-Sorensen ◽  
E.J. Daly ◽  
C.I. Underwood ◽  
J. Ward ◽  
L. Adams
Keyword(s):  
Solar Activity ◽  
High Solar Activity ◽  
Low Altitude

scholarly journals Seasonal features of geomagnetic activity: a study on the solar activity dependence

2021 ◽  
Vol 39 (5) ◽  
pp. 929-943
Author(s):  
Adriane Marques de Souza Franco ◽  
Rajkumar Hajra ◽  
Ezequiel Echer ◽  
Mauricio José Alves Bolzan
Keyword(s):  
Solar Wind ◽  
Solar Activity ◽  
Geomagnetic Activity ◽  
Annual Variation ◽  
Geomagnetic Storms ◽  
Solar Wind Speed ◽  
Solar Cycles ◽  
Annual Variations ◽  
Long Duration ◽  
Activity Dependence

Abstract. Seasonal features of geomagnetic activity and their solar-wind–interplanetary drivers are studied using more than five solar cycles of geomagnetic activity and solar wind observations. This study involves a total of 1296 geomagnetic storms of varying intensity identified using the Dst index from January 1963 to December 2019, a total of 75 863 substorms identified from the SuperMAG AL/SML index from January 1976 to December 2019 and a total of 145 high-intensity long-duration continuous auroral electrojet (AE) activity (HILDCAA) events identified using the AE index from January 1975 to December 2017. The occurrence rates of the substorms and geomagnetic storms, including moderate (-50nT≥Dst>-100nT) and intense (-100nT≥Dst>-250nT) storms, exhibit a significant semi-annual variation (periodicity ∼6 months), while the super storms (Dst≤-250 nT) and HILDCAAs do not exhibit any clear seasonal feature. The geomagnetic activity indices Dst and ap exhibit a semi-annual variation, while AE exhibits an annual variation (periodicity ∼1 year). The annual and semi-annual variations are attributed to the annual variation of the solar wind speed Vsw and the semi-annual variation of the coupling function VBs (where V = Vsw, and Bs is the southward component of the interplanetary magnetic field), respectively. We present a detailed analysis of the annual and semi-annual variations and their dependencies on the solar activity cycles separated as the odd, even, weak and strong solar cycles.

scholarly journals Winter anomaly in NmF2 and TEC: when and where it can occur

2018 ◽  
Vol 8 ◽  
pp. A45 ◽  
Author(s):  
Yury V. Yasyukevich ◽  
Anna S. Yasyukevich ◽  
Konstantin G. Ratovsky ◽  
Maxim V. Klimenko ◽  
Vladimir V. Klimenko ◽  
...  
Keyword(s):  
Solar Activity ◽  
Meridional Wind ◽  
Global Scale ◽  
Activity Level ◽  
Electron Content ◽  
Intensity Increase ◽  
Total Electron ◽  
Solar Activity Level ◽  
Winter Anomaly ◽  
Activity Dependence

For the first time, by using a regression procedure, we analyzed the solar activity dependence of the winter anomaly intensity in the ionospheric F2-layer peak electron density (Nm F2) and in the Total Electron Content (TEC) on a global scale. We used the data from global ionospheric maps for 1998–2015, from GPS radio occultation observations with COSMIC, CHAMP, and GRACE satellites for 2001–2015, and ground-based ionosonde data. The fundamental features of the winter anomaly in Nm F2 and in TEC (spatial distribution and solar activity dependence) are similar for these parameters. We determined the regions, where the winter anomaly may be observed in principle, and the solar activity level, at which the winter anomaly may be recorded in different sectors. A growth in geomagnetic disturbance or in the solar activity level is shown to facilitate the winter anomaly intensity increase. Longitudinal variations in the winter anomaly intensity do not conform partly to the generally accepted Rishbeth theory. We consider the obtained results in the context of spatial and solar cycle variations in O/N2 ratio and thermospheric meridional wind. Additionally, we briefly discuss different definitions of the winter anomaly.

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