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Temporal Offsets between Maximum CME Speed Index and Solar, Geomagnetic, and Interplanetary Indicators during Solar Cycle 23 and the Ascending Phase of Cycle 24  

Ali Kilcik   Submitted: 2016-04-20 23:52

On the basis of morphological analysis of yearly values of the maximum CME (coronal mass ejection) speed index, the sunspot number and total sunspot area, sunspot magnetic field, and solar flare index, the solar wind speed and interplanetary magnetic field strength, and the geomagnetic Ap and Dst indices, we point out the particularities of solar and geomagnetic activity during the last cycle 23, the long minimum which followed it and the ascending branch of cycle 24. We also analyze temporal offset between the maximum CME speed index and the above-mentioned solar, geomagnetic, and interplanetary indices. It is found that this solar activity index, analyzed jointly with other solar activity, interplanetary parameters, and geomagnetic activity indices, shows a hysteresis phenomenon. It is observed that these parameters follow different paths for the ascending and the descending phases of solar cycle 23. It is noticed that the hysteresis phenomenon represents a clue in the search for physical processes responsible for linking the solar activity to the near-Earth and geomagnetic responses.

Authors: A. Özgüç, A. Kilcik, K. Georgieva, B. Kirov
Projects: None

Publication Status: Accepted for publication by Solar Physics
Last Modified: 2016-04-26 07:40
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Active Latitude Oscillations Observed on the Sun  

Ali Kilcik   Submitted: 2016-04-04 06:26

We investigate periodicities in mean heliographic latitudes of sunspot groups, called active latitudes, for the last six complete solar cycles (1945-2008). For this purpose, the Multi Taper Method and Morlet Wavelet analysis methods were used. We found the following: 1) Solar rotation periodicities (26-38 days) are present in active latitudes of both hemispheres for all the investigated cycles (18 to 23). 2) Both in the northern and southern hemispheres, active latitudes drifted towards the equator starting from the beginning to the end of each cycle by following an oscillating path. These motions are well described by a second order polynomial. 3) There are no meaningful periods between 55 and about 300 days in either hemisphere for all cycles. 4) A 300 to 370 day periodicity appears in both hemispheres for Cycle 23, in the northern hemisphere for Cycle 20, and in the southern hemisphere for Cycle 18.

Authors: A. Kilcik, V. Yurchyshyn, F. Clette, A. Özgüç, J.-P. Rozelot
Projects:

Publication Status: Accepted for publication by Solar Physics
Last Modified: 2016-04-09 13:59
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One Possible Reason for Double-Peaked Maxima in Solar Cycles: Is a Second Maximum of Solar Cycle 24 Coming?  

Ali Kilcik   Submitted: 2013-09-03 09:59

We investigate solar activity by focusing on double maxima in solar cycles and try to estimate the shape of the current solar cycle (Cycle 24) during its maximum. We analyzed data for Solar Cycle 24 by using Learmonth Solar Observatory sunspot group data since 2008. All sunspot groups (SGs) recorded during this time interval were separated into two groups: The first group includes small SGs [A, B, C, H, classes by the Zurich classification], and the second group consists of large SGs [D, E, and F]. We then calculated small and large sunspot group numbers, their sunspot numbers [SSN] and Zurich numbers [Rz] from their daily mean numbers as observed on the solar disk during a given month. We found that the temporal variations for these three different separations behave similarly. We also analyzed the general shape of solar cycles from Cycle 1 to 23 by using monthly International Sunspot Number [ISSN] data and found that the durations of maxima were about 2.9 years. Finally, we used ascending time and SSN relationship and found that the maximum of the Cycle 24 should be later than 2011. Thus, we conclude that i) one possible reason for a double maximum in solar cycles is the different behavior of large and small sunspot groups, and ii) a double maximum is coming for Solar Cycle 24.

Authors: A. Kilcik & A. Özgüç
Projects: None

Publication Status: Accepted by Solar Physics
Last Modified: 2013-09-03 12:22
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Properties of Umbral Dots as Measured from the New Solar Telescope Data and MHD Simulations  

Ali Kilcik   Submitted: 2011-11-18 12:40

We studied bright umbral dots (UDs) detected in a moderate size sunspot andcompared their statistical properties to recent MHD models. The study is basedon high resolution data recorded by the New Solar Telescope at the Big BearSolar Observatory and 3D MHD simulations of sunspots. Observed UDs, livinglonger than 150 s, were detected and tracked in a 46 min long data set, usingan automatic detection code. Total 1553 (620) UDs were detected in thephotospheric (low chromospheric) data. Our main findings are: i) none of theanalyzed UDs is precisely circular, ii) the diameter-intensity relationshiponly holds in bright umbral areas, and iii) UD velocities are inversely relatedto their lifetime. While nearly all photospheric UDs can be identified in thelow chromospheric images, some small closely spaced UDs appear in the lowchromosphere as a single cluster. Slow moving and long living UDs seem to existin both the low chromosphere and photosphere, while fast moving and shortliving UDs are mainly detected in the photospheric images. Comparison to the 3DMHD simulations showed that both types of UDs display, on average, very similarstatistical characteristics. However, i) the average number of observed UDs perunit area is smaller than that of the model UDs, and ii) on average, thediameter of model UDs is slightly larger than that of observed ones.

Authors: A. Kilcik, V. B. Yurchyshyn, M. Rempel, V. Abramenko, R. Kitai, P. R. Goode, W. Cao, H. Watanabe
Projects: None

Publication Status: Accepted by ApJ
Last Modified: 2011-11-22 02:49
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Time Distributions of Large and Small Sunspot Groups Over Four Solar Cycles  

Ali Kilcik   Submitted: 2011-11-18 12:35

Here we analyze solar activity by focusing on time variations of the number of sunspot groups (SGs) as a function of their modified Zurich class. We analyzed data for solar cycles 2023 by using Rome (cycles 2021) and Learmonth Solar Observatory (cycles 2223) SG numbers. All SGs recorded during these time intervals were separated into two groups. The first group includes small SGs (A, B, C, H, and J classes by Zurich classification) and the second group consists of large SGs (D, E, F, and G classes). We then calculated small and large SG numbers from their daily mean numbers as observed on the solar disk during a given month. We report that the time variations of small and large SG numbers are asymmetric except for the solar cycle 22. In general large SG numbers appear to reach their maximum in the middle of the solar cycle (phase 0.450.5), while the international sunspot numbers and the small SG numbers generally peak much earlier (solar cycle phase 0.290.35). Moreover, the 10.7 cm solar radio flux, the facular area, and the maximum CME speed show better agreement with the large SG numbers than they do with the small SG numbers. Our results suggest that the large SG numbers are more likely to shed light on solar activity and its geophysical implications. Our findings may also influence our understanding of long term variations of the total solar irradiance, which is thought to be an important factor in the Sun - Earth climate relationship.

Authors: Kilcik, A.; Yurchyshyn, V. B.; Abramenko, V.; Goode, P. R.; Özgüç, A.; Rozelot, J. P.; Cao, W.
Projects: None

Publication Status: Published in 2011, Astrophys. J. 731, article id. 30 DOI:10.1088/0004-637X/731/1/30
Last Modified: 2011-11-22 02:49
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Maximum CME speed as an indicator of solar and geomagnetic activities  

Ali Kilcik   Submitted: 2011-11-18 12:31

We investigate the relationship between the monthly averaged maximal speeds of coronal mass ejections (CMEs), international sunspot number (ISSN), and the geomagnetic Dst and Ap indices covering the 1996-2008 time interval (solar cycle 23). Our new findings are as follows. (1) There is a noteworthy relationship between monthly averaged maximum CME speeds and sunspot numbers, Ap and Dst indices. Various peculiarities in the monthly Dst index are correlated better with the fine structures in the CME speed profile than that in the ISSN data. (2) Unlike the sunspot numbers, the CME speed index does not exhibit a double peak maximum. Instead, the CME speed profile peaks during the declining phase of solar cycle 23. Similar to the Ap index, both CME speed and the Dst indices lag behind the sunspot numbers by several months. (3) The CME number shows a double peak similar to that seen in the sunspot numbers. The CME occurrence rate remained very high even near the minimum of the solar cycle 23, when both the sunspot number and the CME average maximum speed were reaching their minimum values. (4) A well-defined peak of the Ap index between 2002 May and 2004 August was co-temporal with the excess of the mid-latitude coronal holes during solar cycle 23. The above findings suggest that the CME speed index may be a useful indicator of both solar and geomagnetic activities. It may have advantages over the sunspot numbers, because it better reflects the intensity of Earth-directed solar eruptions.

Authors: A. Kilcik, V.B. Yurchyshyn, V. Abramenko, P.R. Goode, N. Gopalswamy, A. Özgüç, J.P. Rozelot
Projects: SoHO-LASCO

Publication Status: Published in 2011, Astrophys. J. 727, article id. 44 DOI: 10.1088/0004-637X/727/1/44
Last Modified: 2011-11-22 02:49
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Abstracts by Author
Temporal Offsets between Maximum CME Speed Index and Solar, Geomagnetic, and Interplanetary Indicators during Solar Cycle 23 and the Ascending Phase of Cycle 24
Active Latitude Oscillations Observed on the Sun
One Possible Reason for Double-Peaked Maxima in Solar Cycles: Is a Second Maximum of Solar Cycle 24 Coming?
Properties of Umbral Dots as Measured from the New Solar Telescope Data and MHD Simulations
Time Distributions of Large and Small Sunspot Groups Over Four Solar Cycles
Maximum CME speed as an indicator of solar and geomagnetic activities

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