The causes of geomagnetic storms during solar maximum

Eos ◽  
1994 ◽  
Vol 75 (5) ◽  
pp. 49 ◽  
Author(s):  
Bruce T. Tsurutani ◽  
Walter D. Gonzalez
Keyword(s):  
Geomagnetic Storms ◽  
Solar Maximum

scholarly journals Formation of a strong southward IMF near the solar maximum of cycle 23

2004 ◽  
Vol 22 (2) ◽  
pp. 673-687 ◽  
Author(s):  
S. Watari ◽  
M. Vandas ◽  
T. Watanabe
Keyword(s):  
Solar Wind ◽  
Magnetic Fields ◽  
Geomagnetic Storms ◽  
Solar Maximum ◽  
Interplanetary Shocks ◽  
Physical Processes ◽  
Interplanetary Magnetic Fields ◽  
Interplanetary Physics ◽  
Solar Wind Parameters ◽  
Interplanetary Disturbance

Abstract. We analyzed observations of the solar activities and the solar wind parameters associated with large geomagnetic storms near the maximum of solar cycle 23. This analysis showed that strong southward interplanetary magnetic fields (IMFs), formed through interaction between an interplanetary disturbance, and background solar wind or between interplanetary disturbances are an important factor in the occurrence of intense geomagnetic storms. Based on our analysis, we seek to improve our understanding of the physical processes in which large negative Bz's are created which will lead to improving predictions of space weather. Key words. Interplanetary physics (Flare and stream dynamics; Interplanetary magnetic fields; Interplanetary shocks)

scholarly journals Solar cycle effect on geomagnetic storms caused by interplanetary magnetic clouds

2006 ◽  
Vol 24 (12) ◽  
pp. 3383-3389 ◽  
Author(s):  
C.-C. Wu ◽  
R. P. Lepping
Keyword(s):  
Solar Wind ◽  
Geomagnetic Storm ◽  
Solar Minimum ◽  
Geomagnetic Storms ◽  
Solar Maximum ◽  
Solar Wind Speed ◽  
Magnetic Clouds ◽  
Active Period ◽  
Quiet Period ◽  
Solar Wind Parameters

Abstract. We investigated geomagnetic activity which was induced by interplanetary magnetic clouds during the past four solar cycles, 1965–1998. We have found that the intensity of such geomagnetic storms is more severe in solar maximum than in solar minimum. In addition, we affirm that the average solar wind speed of magnetic clouds is faster in solar maximum than in solar minimum. In this study, we find that solar activity level plays a major role on the intensity of geomagnetic storms. In particular, some new statistical results are found and listed as follows. (1) The intensity of a geomagnetic storm in a solar active period is stronger than in a solar quiet period. (2) The magnitude of negative Bzmin is larger in a solar active period than in a quiet period. (3) Solar wind speed in an active period is faster than in a quiet period. (4) VBsmax in an active period is much larger than in a quiet period. (5) Solar wind parameters, Bzmin, Vmax and VBsmax are correlated well with geomagnetic storm intensity, Dstmin during a solar active period. (6) Solar wind parameters, Bzmin, and VBsmax are not correlated well (very poorly for Vmax) with geomagnetic storm intensity during a solar quiet period. (7) The speed of the solar wind plays a key role in the correlation of solar wind parameters vs. the intensity of a geomagnetic storm. (8) More severe storms with Dstmin≤−100 nT caused by MCs occurred in the solar active period than in the solar quiet period.

scholarly journals Carrington Longitudinal and Solar Cycle Distribution of the Super Active Regions From 1976 to 2018

2021 ◽  
Author(s):  
MIng-Xian Zhao ◽  
Guiming Le ◽  
Yonghua Liu ◽  
Tian Mao
Keyword(s):  
Solar Cycle ◽  
Space Weather ◽  
Geomagnetic Storms ◽  
Solar Maximum ◽  
Active Regions ◽  
Ground Level ◽  
Weather Events ◽  
Flare Index ◽  
Statistical Results ◽  
Extreme Space Weather Events

Abstract We studied the Carrington longitudinal and solar cycle distribution of the super active regions (SARs) from 1976to 2018. There were 51 SARs during this period. We divided the SARs into SARs1 and SARs2. SARs1 refers tothe SARs that produced extreme space weather events including ≥X5.0 flares, ground level events (GLEs) andsuper geomagnetic storms (SGSs: Dst≤ −250 nT), while SARs2 did not produce extreme space weather events.The total number of SARs1 and SARs2 are 32 and 19, respectively. The statistical results show that 34.4%, 65.6%and 78.1% of the SARs1 appeared in the ascending phase, descending phase and in the period from two yearsbefore to the three years after the solar maximum, respectively, while 52.6%, 47.4% and 100% of the SARs2appeared in the ascending phase, descending phase and in the period from two years before to the three years aftersolar maximum, respectively. The Carrington longitude distribution of the SARs1 shows that SARs1 in thelongitudinal scope of [0,150°] produced ≥X5.0 flares and GLEs, while only the SARs1 in the longitude range of[150°,360°] not only produced ≥X5.0 flares and GLEs, but also produced SGSs. The total number of SARsduring a SC has a good correlation with the SC size. However, the largest flare index of a SAR within a SC has apoor correlation with the SC size, implying that the number of SARs in a weak SC will be small. However, aweak SC may have a SAR that can produce very strong solar flare activities.

scholarly journals Relationships between the AE, ap and Dst indices near solar minimum (1974) and at solar maximum (1979)

1997 ◽  
Vol 15 (10) ◽  
pp. 1265-1270 ◽  
Author(s):  
M. M. Fares Saba ◽  
W. D. Gonzalez ◽  
A. L. Clúa de Gonzalez
Keyword(s):  
Seasonal Variation ◽  
Solar Minimum ◽  
Ring Current ◽  
Geomagnetic Storms ◽  
Solar Maximum ◽  
Correlation Coefficients ◽  
The Sun ◽  
Yearly Average ◽  
First Time ◽  
Activity Indices

Abstract. Three-hourly average values of the Dst, AE and ap geomagnetic activity indices have been studied for 1 year's duration near the solar minimum (1974) and also at the solar maximum (1979). In 1979 seven intense geomagnetic storms (Dst <–100 nT) occurred, whereas in 1974 only three were reported. This study reveals: (1) the yearly average of AE is greater in 1974 than in 1979, whereas the inverse seems to be true for the yearly average of Dst, when a higher number of intense storms is present. These averages indicate the kind of activity occurring on the sun as shown in earlier work. (2) The seasonal variation of Dst is higher than that of ap and is almost negligible in AE. (3) The correlation coefficient of ap × AE is in general the highest, as the magnetometers that monitor both indices are close, and is surpassed only by the ap × Dst correlation during geomagnetic storms, when the influence of the ring current is dominant. The correlation of ap × Dst also shows a seasonal variability. (4) For the first time a study of correlation between ap and a linear combination of AE and Dst has also been made. We found higher correlation coefficients in this case as compared to those between ap × Dst and ap × AE.

scholarly journals Variation of Solar Wind Parameters During Intense Geomagnetic Storms

2017 ◽  
pp. 80-85 ◽  
Author(s):  
Ayush Subedi ◽  
Binod Adhikari ◽  
Roshan Kumar Mishra
Keyword(s):  
Solar Wind ◽  
Geomagnetic Storms ◽  
Solar Maximum ◽  
Coronal Holes ◽  
Research Work ◽  
Energy Coupling ◽  
Solar Wind Plasma ◽  
Geomagnetic Disturbance ◽  
Strong Impact ◽  
Geomagnetic Disturbances

Geomagnetic disturbances are caused by enhanced solar wind magnetospheric energy coupling process. The principal cause of geomagnetic disturbance is the magnetic reconnection that establishes an electrodynamical coupling between the solar wind plasma and magnetosphere. Around solar maximum, the main structures emanating from the sun are sporadic Coronal Mass Ejection (CMEs) and their interplanetary counterparts (ICMEs). During the descending and minimum solar cycle phases, coronal holes occur more often. They appear as dark regions confined to Solar poles during the solar maximum but expand in size and moves toward the solar equator during the descending phase. In this work, we have taken three different geomagnetic storms during solar maxima. For the interpretation of events, we used interplanetary solar wind data and geomagnetic indices. These satellite data and Dst indices (ranging from -100nT to above) are interpreted by using the method of cross correlation. The values of Bz found approximately 20nT, -50nT and -20nT respectively. Similarly, the value of Dst is -250nT, -400nT and -300nT which shows very intense effect. Likewise, the correlation coefficient we obtained from this research work strongly suggest that interplanetary magnetic field Bz has strong impact for the cause of geomagnetic storms.The Himalayan Physics Vol. 6 & 7, April 2017 (80-85)

scholarly journals Interplanetary-magnetosphere coupling during intense geomagnetic storms at solar maximum

1992 ◽  
Vol 31 (1) ◽  
pp. 11-18
Author(s):  
W. D. González ◽  
A. L. Calu de González ◽  
B. T. Tsurutani
Keyword(s):  
Geomagnetic Storms ◽  
Solar Maximum

Durante el intervalo del 16 de agosto de 1978 al 28 de diciembre de 1979, 90% de las tempestades geomagnéticas intensas (Dst < -100nT) fueron precedidas por la llegada a 1AU de ondas de choque interplanetarias rápidas, conforme fueron identificadas con los datos de plasma y campos magnéticos colectados por la nave espacial ISEE-3. En la relación con estos eventos, discutiremos las estructuras interplanetarias asociadas a campos magnéticos Bz negativos, de gran amplitud y larga duración, que se consideran como la causa principal de las tempestades intensas. Presentaremos también un resumen de las funciones de acoplamiento interplanetario- magnetosféricas, basadas en el proceso de reconexión en la magnetopausa terrestre. Terminaremos con una revisión sucinta de la evolución a largo plazo de las tempestades geomagnéticas intensas, tales como las mostradas en las distribuciones estacionales y del ciclo solar.

Geomagnetic storms contrasted during solar maximum and near solar minimum

2002 ◽  
Vol 30 (10) ◽  
pp. 2301-2304 ◽  
Author(s):  
W.D Gonzalez ◽  
B.T Tsurutani ◽  
A.L Clúa de Gonzalez
Keyword(s):  
Solar Minimum ◽  
Geomagnetic Storms ◽  
Solar Maximum

scholarly journals A statistical comparison of hot-ion properties at geosynchronous orbit during intense and moderate geomagnetic storms at solar maximum and minimum

2006 ◽  
Vol 111 (A7) ◽  
Author(s):  
Jichun Zhang ◽  
Michael W. Liemohn ◽  
Michelle F. Thomsen ◽  
Janet U. Kozyra ◽  
Michael H. Denton ◽  
...  
Keyword(s):  
Geomagnetic Storms ◽  
Solar Maximum ◽  
Geosynchronous Orbit ◽  
Statistical Comparison

scholarly journals A comparison of coronal mass ejections identified by manual and automatic methods

2008 ◽  
Vol 26 (10) ◽  
pp. 3103-3112 ◽  
Author(s):  
S. Yashiro ◽  
G. Michalek ◽  
N. Gopalswamy
Keyword(s):  
Coronal Mass Ejections ◽  
Geomagnetic Storms ◽  
Solar Maximum ◽  
Automatic Identification ◽  
Significant Discrepancy ◽  
Low Latitudes ◽  
Long Time ◽  
Automatic Methods ◽  
Global Understanding ◽  
Good Agreement

Abstract. Coronal mass ejections (CMEs) are related to many phenomena (e.g. flares, solar energetic particles, geomagnetic storms), thus compiling of event catalogs is important for a global understanding these phenomena. CMEs have been identified manually for a long time, but in the SOHO era, automatic identification methods are being developed. In order to clarify the advantage and disadvantage of the manual and automatic CME catalogs, we examined the distributions of CME properties listed in the CDAW (manual) and CACTus (automatic) catalogs. Both catalogs have a good agreement on the wide CMEs (width>120°) in their properties, while there is a significant discrepancy on the narrow CMEs (width≤30°): CACTus has a larger number of narrow CMEs than CDAW. We carried out an event-by-event examination of a sample of events and found that the CDAW catalog have missed many narrow CMEs during the solar maximum. Another significant discrepancy was found on the fast CMEs (speed>1000 km/s): the majority of the fast CDAW CMEs are wide and originate from low latitudes, while the fast CACTus CMEs are narrow and originate from all latitudes. Event-by-event examination of a sample of events suggests that CACTus has a problem on the detection of the fast CMEs.

scholarly journals Extreme Space-Weather Events and the Solar Cycle

Solar Physics ◽  
2021 ◽  
Vol 296 (5) ◽  
Author(s):  
Mathew J. Owens ◽  
Mike Lockwood ◽  
Luke A. Barnard ◽  
Chris J. Scott ◽  
Carl Haines ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Space Weather ◽  
Extreme Events ◽  
Solar Minimum ◽  
Geomagnetic Storms ◽  
Extreme Event ◽  
Solar Maximum ◽  
Solar Cycles ◽  
Event Occurrence

AbstractSpace weather has long been known to approximately follow the solar cycle, with geomagnetic storms occurring more frequently at solar maximum than solar minimum. There is much debate, however, about whether the most hazardous events follow the same pattern. Extreme events – by definition – occur infrequently, and thus establishing their occurrence behaviour is difficult even with very long space-weather records. Here we use the 150-year $aa_{H}$ a a H record of global geomagnetic activity with a number of probabilistic models of geomagnetic-storm occurrence to test a range of hypotheses. We find that storms of all magnitudes occur more frequently during an active phase, centred on solar maximum, than during the quiet phase around solar minimum. We also show that the available observations are consistent with the most extreme events occurring more frequently during large solar cycles than small cycles. Finally, we report on the difference in extreme-event occurrence during odd- and even-numbered solar cycles, with events clustering earlier in even cycles and later in odd cycles. Despite the relatively few events available for study, we demonstrate that this is inconsistent with random occurrence. We interpret this finding in terms of the overlying coronal magnetic field and enhanced magnetic-field strengths in the heliosphere, which act to increase the geoeffectiveness of sheath regions ahead of extreme coronal mass ejections. Putting the three “rules” together allows the probability of extreme event occurrence for Solar Cycle 25 to be estimated, if the magnitude and length of the coming cycle can be predicted. This highlights both the feasibility and importance of solar-cycle prediction for planning and scheduling of activities and systems that are affected by extreme space weather.

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