scholarly journals IPIM Modeling of the Ionospheric F 2 Layer Depletion at High Latitudes During a High-Speed Stream Event

2018 ◽  
Vol 123 (8) ◽  
pp. 7051-7066 ◽  
Author(s):  
A. Marchaudon ◽  
P.-L. Blelly ◽  
M. Grandin ◽  
A. Aikio ◽  
A. Kozlovsky ◽  
...  
Keyword(s):  
High Speed ◽  
High Latitudes ◽  
High Speed Stream

scholarly journals High-speed stream impacts on the equatorial ionization anomaly region during the deep solar minimum year 2008

2012 ◽  
Vol 117 (A10) ◽  
pp. n/a-n/a ◽  
Author(s):  
Jing Liu ◽  
Libo Liu ◽  
Biqiang Zhao ◽  
Yong Wei ◽  
Lianhuan Hu ◽  
...  
Keyword(s):  
Solar Minimum ◽  
High Speed ◽  
High Speed Stream ◽  
Equatorial Ionization Anomaly ◽  
Anomaly Region

scholarly journals A statistical study of the long-term evolution of coronal hole properties as observed by SDO

2020 ◽  
Vol 638 ◽  
pp. A68 ◽  
Author(s):  
S. G. Heinemann ◽  
V. Jerčić ◽  
M. Temmer ◽  
S. J. Hofmeister ◽  
M. Dumbović ◽  
...  
Keyword(s):  
Solar Wind ◽  
Magnetic Flux ◽  
Coronal Hole ◽  
High Speed ◽  
Coronal Holes ◽  
Magnetic Flux Density ◽  
High Speed Stream ◽  
Term Evolution ◽  
Hole Area

Context. Understanding the evolution of coronal holes is especially important when studying the high-speed solar wind streams that emanate from them. Slow- and high-speed stream interaction regions may deliver large amounts of energy into the Earth’s magnetosphere-ionosphere system, cause geomagnetic storms, and shape interplanetary space. Aims. By statistically investigating the long-term evolution of well-observed coronal holes we aim to reveal processes that drive the observed changes in the coronal hole parameters. By analyzing 16 long-living coronal holes observed by the Solar Dynamic Observatory, we focus on coronal, morphological, and underlying photospheric magnetic field characteristics, and investigate the evolution of the associated high-speed streams. Methods. We use the Collection of Analysis Tools for Coronal Holes to extract and analyze coronal holes using 193 Å EUV observations taken by the Atmospheric Imaging Assembly as well as line–of–sight magnetograms observed by the Helioseismic and Magnetic Imager. We derive changes in the coronal hole properties and look for correlations with coronal hole evolution. Further, we analyze the properties of the high–speed stream signatures near 1AU from OMNI data by manually extracting the peak bulk velocity of the solar wind plasma. Results. We find that the area evolution of coronal holes shows a general trend of growing to a maximum followed by a decay. We did not find any correlation between the area evolution and the evolution of the signed magnetic flux or signed magnetic flux density enclosed in the projected coronal hole area. From this we conclude that the magnetic flux within the extracted coronal hole boundaries is not the main cause for its area evolution. We derive coronal hole area change rates (growth and decay) of (14.2 ± 15.0)×108 km2 per day showing a reasonable anti-correlation (ccPearson = −0.48) to the solar activity, approximated by the sunspot number. The change rates of the signed mean magnetic flux density (27.3 ± 32.2 mG day−1) and the signed magnetic flux (30.3 ± 31.5 1018 Mx day−1) were also found to be dependent on solar activity (ccPearson = 0.50 and ccPearson = 0.69 respectively) rather than on the individual coronal hole evolutions. Further we find that the relation between coronal hole area and high-speed stream peak velocity is valid for each coronal hole over its evolution, but we see significant variations in the slopes of the regression lines.

scholarly journals The proton and electron radiation belts at geosynchronous orbit: Statistics and behavior during high-speed stream-driven storms

2016 ◽  
Vol 121 (6) ◽  
pp. 5449-5488 ◽  
Author(s):  
Joseph E. Borovsky ◽  
Thomas E. Cayton ◽  
Michael H. Denton ◽  
Richard D. Belian ◽  
Roderick A. Christensen ◽  
...  
Keyword(s):  
High Speed ◽  
Radiation Belts ◽  
Geosynchronous Orbit ◽  
Electron Radiation ◽  
High Speed Stream ◽  
And Behavior

scholarly journals An alternative way to identify local geomagnetically quiet days: a case study using wavelet analysis

2016 ◽  
Vol 34 (4) ◽  
pp. 451-462 ◽  
Author(s):  
Virginia Klausner ◽  
Andrés Reinaldo Rodriguez Papa ◽  
Cláudia Maria Nicole Cândido ◽  
Margarete Oliveira Domingues ◽  
Odim Mendes
Keyword(s):  
Wavelet Analysis ◽  
Geomagnetic Activity ◽  
Solar Minimum ◽  
High Speed ◽  
Wavelet Coefficient ◽  
Magnetic Activity ◽  
New Method ◽  
Storm Events ◽  
High Speed Stream

Abstract. This paper proposes a new method to evaluate geomagnetic activity based on wavelet analysis during the solar minimum activity (2007). In order to accomplish this task, a newly developed algorithm called effectiveness wavelet coefficient (EWC) was applied. Furthermore, a comparison between the 5 geomagnetically quiet days determined by the Kp-based method and by wavelet-based method was performed. This paper provides a new insight since the geomagnetic activity indexes are mostly designed to quantify the extent of disturbance rather than the quietness. The results suggest that the EWC can be used as an alternative tool to accurately detect quiet days, and consequently, it can also be used as an alternative to determine the Sq baseline to the current Kp-based 5 quietest days method. Another important aspect of this paper is that most of the quietest local wavelet candidate days occurred in an interval 2 days prior to the high-speed-stream-driven storm events. In other words, the EWC algorithm may potentially be used to detect the quietest magnetic activity that tends to occur just before the arrival of high-speed-stream-driven storms.

scholarly journals Inner magnetospheric heavy ion composition during high-speed stream-driven storms

2013 ◽  
Vol 118 (7) ◽  
pp. 4066-4079 ◽  
Author(s):  
D. R. Forster ◽  
M. H. Denton ◽  
M. Grande ◽  
C. H. Perry
Keyword(s):  
High Speed ◽  
Heavy Ion ◽  
Ion Composition ◽  
High Speed Stream
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