scholarly journals Response to “Limitations in the Hilbert Transform Approach to Locating Solar Cycle Terminators” by R. Booth

Solar Physics ◽  
2021 ◽  
Vol 296 (10) ◽  
Author(s):  
Robert J. Leamon ◽  
Scott W. McIntosh ◽  
Sandra C. Chapman ◽  
Nicholas W. Watkins
Keyword(s):  
Solar Cycle ◽  
Solar Phys ◽  
Hilbert Transform ◽  
Solar Cycles ◽  
Solar Cycle 24 ◽  
Cycle 24 ◽  
The Hilbert Transform ◽  
Possible Cause ◽  
Sunspot Record

AbstractBooth (Solar Phys.296, 108, 2021; hereafter B21) is essentially a critique of the Hilbert transform techniques used in our paper (Leamon et al., Solar Phys.295, 36, 2020; hereafter L20) to predict the termination of solar cycles. Here we respond to his arguments; our methodology and parameter choices do extract a mathematically robust signature of terminators from the historical sunspot record. We agree that the attempt in L20 to extrapolate beyond the sunspot record gives a failed prediction for the next terminator of May 2020, and we identify both a possible cause and remedy here. However, we disagree with the B21 assessment that the likely termination of Solar Cycle 24 is two years after the date predicted in L20, and we show why.

scholarly journals Super-active regions in solar cycle 24

2015 ◽  
Vol 11 (S320) ◽  
pp. 309-314 ◽  
Author(s):  
Anqin Chen ◽  
Jingxiu Wang
Keyword(s):  
Solar Cycle ◽  
Active Regions ◽  
Total Solar Irradiance ◽  
Flare Activity ◽  
Solar Cycles ◽  
Solar Cycle 24 ◽  
Satisfactory Account ◽  
Current Cycle ◽  
Flare Index ◽  
Cycle 24

AbstractComparing with solar cycles 21-23, the level of solar activity in the current cycle is very low. So far, there have been only five SARs and 45 X class flares. The monthly smoothed total solar irradiance decreased sharply by 0.09% from the maximum of cycle 23 to the minima between cycles 23 and 24. In this contribution, we present new studies on SARs in Cycle 24. The SARs in the current cycle have relatively smaller flare index (Iflare) and composite vector field index (Icom) comparing with the SARs in cycles 22 and 23. There is a clearly linear relationship between Iflare and Icom. The emphasis of this contribution is put on the similarity and different behaviors of vector magnetic fields of the SARs in the current solar cycle and the previous ones. We try to get a satisfactory account for the general characteristics and relatively lower level of solar flare activity in Cycle 24.

scholarly journals Descriptive study of X-class flares released in the year 2014, during the double peak of SC-24

2015 ◽  
Vol 11 (S320) ◽  
pp. 330-332
Author(s):  
Ahmed A. Hady ◽  
Marwa H. Mostafa ◽  
Susan W. Samwel
Keyword(s):  
Data Analysis ◽  
Solar Cycle ◽  
Solar Flares ◽  
Descriptive Study ◽  
Energetic Particles ◽  
Main Peak ◽  
Solar Cycles ◽  
Double Peak ◽  
Solar Cycle 24 ◽  
Cycle 24

AbstractDuring the declining phase of the Solar cycle 24, a new peak appeared on January 7, 2014. The release of x-class flares, with the high energetic particles, were found to be more intense than that occurred during the main peak of the same cycle. Few X-class flares were released, lately, during the year 2014. We note that during the last 5 solar cycles, a new peak has appeared, releasing high energetic particles and X-class solar flares, which are called the secondary peak or the double peak of solar cycle. The aim of this descriptive study is to follow the morphological and magnetic changes of the active region before, during, and after the production of X-class flares according to data analysis. Furthermore, the causes of the release of such eruptive storms have been discussed for the period, year 2014, during the double peak of the solar cycle 24.

scholarly journals Probable Value for the Next Sunspot Minimum

2014 ◽  
Vol 2014 ◽  
pp. 1-4
Author(s):  
Virginia Mabel Silbergleit
Keyword(s):  
Solar Cycle ◽  
Solar Minimum ◽  
The Sun ◽  
Solar Cycles ◽  
Additional Insight ◽  
Sunspot Minimum ◽  
Sunspot Numbers ◽  
Solar Cycle 24 ◽  
Cycle 24

Gumbel’s first distribution is applied to smoothed monthly mean sunspot numbers for solar cycles 10 to 24. According to that, the next minimum for solar cycle 24-25 transition would be the deepest solar minimum of the last 150 years. This study provides an additional insight about changes in the Sun which are currently happening.

scholarly journals The Statistical Analysis of Characteristics of Coronal Mass Ejection During the Descending Phase of Solar Cycle 23 and 24

2021 ◽  
Vol 16 (2) ◽  
Author(s):  
Hemlata Dharmashaktu ◽  
N.K. Lohani
Keyword(s):  
Solar Cycle ◽  
Angular Width ◽  
Maximum Speed ◽  
Solar Cycles ◽  
Linear Speed ◽  
23Rd Solar Cycle ◽  
23Rd Cycle ◽  
Solar Cycle 23 ◽  
Solar Cycle 24 ◽  
Cycle 24

The characteristics of CMEs we studied are angular width, linear speed, and acceleration for all categories of CMEs such as narrow (W ≤20°), intermediate (20°< W<200°), wide (W ≥ 200°) and linear speed <500 km/s during the descending phase of solar cycle 23 and 24 and compared them. We have found that there are 1951 narrow CMEs during solar cycle 23 that is 1.9 times greater than in solar cycle 24 (1047). On the other side, the number of intermediate CMEs during solar cycle 24 (1571) is 1.14 times more than solar cycle 23 (1162). We observed no noticeable difference between the number of wide CMEs of solar cycle 23 (29) and 24 (36). The angular width of CMEs during the descending phase of solar cycle 23 and solar cycle 24, predominately distributed around 100-600. The fascinating result is that the angular width distributions for the descending phase of solar cycles are approximately identical. On comparing the results of linear speed of both solar cycle, we can say that, (i) 93.7% (1729) and 87.7% (908) of narrow CMEs, (ii) 97% (1328) and 94% (1479) of intermediate CMEs and (iii) 44% (13) and 42% (15) of wide CMEs have speed of <500 km s-1, respectively. Mostly the fractions of narrow and intermediate CMEs decline sharply at the speeds greater than 500 km s-1. The maximum speed observed during the 23rd cycle is 1994 km/s (wide CME) and the 24th cycle is 3163 km/s (wide CME) respectively. It was noticed that the speed of the 24th solar cycle CME is higher than the 23rd solar cycle CME. The major fraction of CMEs has acceleration in the range of -20 to 20 km s-2, all types of CMEs. The narrow and intermediate CMEs mostly show acceleration while wide CMEs show deceleration.

scholarly journals GLOBAL DISTURBANCE OF EARTH’S MAGNETOSPHERE AND ITS CONNECTION WITH SPACE WEATHER

2020 ◽  
Vol 6 (1) ◽  
pp. 51-62
Author(s):  
Nadezhda Kurazhkovskaya
Keyword(s):  
Solar Wind ◽  
Solar Cycle ◽  
Space Weather ◽  
Interplanetary Medium ◽  
Dynamic Pressure ◽  
Annual Number ◽  
Solar Cycles ◽  
Winter Solstice ◽  
Solar Cycle 24 ◽  
Cycle 24

This paper deals with extreme conditions of the global magnetosphere disturbance: very quiet and greatly disturbed, and their relationship with interplanetary medium parameters. The degree of global magnetosphere disturbance was estimated from the monthly and annual number of magnetically quiet and magnetically disturbed days. The cyclic and seasonal distributions of magnetically quiet and disturbed days were compared, and their relationship with interplanetary medium parameters in solar cycles 20–24 was analyzed. Magnetically quiet days are shown to be mainly observed at the ascending phase of solar activity and during the winter solstice season. Magnetically disturbed days dominate at the descending phase of the solar cycle and during the equinox season. An anomalously large increase in the number of quiet days was found in solar cycle 24 as compared to previous cycles. It has been established that the cyclic variation in the annual number of quiet and disturbed days is determined by the behavior and magnitude of the speed, temperature, dynamic pressure of solar wind plasma and the interplanetary magnetic field modulus. The detected burst in the number of quiet days during the ascending phase of solar cycle 24 is assumed to reflect internal processes on the Sun and related changes in interplanetary medium parameters. The patterns of cyclical and seasonal variation in the number of magnetically quiet and disturbed days and their relationship with the solar wind parameters can be used to predict space weather.

The Prediction of Maximum Amplitudes of Solar Cycles and the Maximum Amplitude of Solar Cycle 24

2002 ◽  
Vol 2 (6) ◽  
pp. 557-562 ◽  
Author(s):  
Jia-Long Wang ◽  
Jian-Cun Gong ◽  
Si-Qing Liu ◽  
Gui-Ming Le ◽  
Jing-Lan Sun
Keyword(s):  
Solar Cycle ◽  
Maximum Amplitude ◽  
Solar Cycles ◽  
Solar Cycle 24 ◽  
Cycle 24

scholarly journals GLOBAL DISTURBANCE OF EARTH’S MAGNETOSPHERE AND ITS CONNECTION WITH SPACE WEATHER

2020 ◽  
Vol 6 (1) ◽  
pp. 41-49 ◽  
Author(s):  
Nadezhda Kurazhkovskaya
Keyword(s):  
Solar Wind ◽  
Solar Cycle ◽  
Space Weather ◽  
Interplanetary Medium ◽  
Dynamic Pressure ◽  
Annual Number ◽  
Solar Cycles ◽  
Winter Solstice ◽  
Solar Cycle 24 ◽  
Cycle 24

This paper deals with extreme conditions of the global magnetosphere disturbance: very quiet and greatly disturbed, and their relationship with interplanetary medium parameters. The degree of global magnetosphere disturbance was estimated from the monthly and annual number of magnetically quiet and magnetically disturbed days. The cyclic and seasonal distributions of magnetically quiet and disturbed days were compared, and their relationship with interplanetary medium parameters in solar cycles 20–24 was analyzed. Magnetically quiet days are shown to be mainly observed at the ascending phase of solar activity and during the winter solstice season. Magnetically disturbed days dominate at the descending phase of the solar cycle and during the equinox season. An anomalously large increase in the number of quiet days was found in solar cycle 24 as compared to previous cycles. It has been established that the cyclic variation in the annual number of quiet and disturbed days is determined by the behavior and magnitude of the speed, temperature, dynamic pressure of solar wind plasma and the interplanetary magnetic field modulus. The detected burst in the number of quiet days during the ascending phase of solar cycle 24 is assumed to reflect internal processes on the Sun and related changes in interplanetary medium parameters. The patterns of cyclical and seasonal variation in the number of magnetically quiet and disturbed days and their relationship with the solar wind parameters can be used to predict space weather.

Regression Analysis of Sunspot Numbers for the Solar Cycle 24 in Comparison to Previous Three Cycles

2014 ◽  
Vol 4 (2) ◽  
pp. 477-483
Author(s):  
Debojyoti Halder
Keyword(s):  
Regression Analysis ◽  
Solar Cycle ◽  
Sunspot Number ◽  
The Sun ◽  
Sunspot Numbers ◽  
Solar Cycle 24 ◽  
Current Cycle ◽  
Cycle 24

Sunspots are temporary phenomena on the photosphere of the Sun which appear visibly as dark spots compared to surrounding regions. Sunspot populations usually rise fast but fall more slowly when observed for any particular solar cycle. The sunspot numbers for the current cycle 24 and the previous three cycles have been plotted for duration of first four years for each of them. It appears that the value of peak sunspot number for solar cycle 24 is smaller than the three preceding cycles. When regression analysis is made it exhibits a trend of slow rising phase of the cycle 24 compared to previous three cycles. Our analysis further shows that cycle 24 is approaching to a longer-period but with smaller occurrences of sunspot number.

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