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1.
The purpose of this paper is to study the nature of variation of O3 concentration of Antarctic Survey Stations and its correlation with solar ultraviolet radiation. Solar UV data for the period November 1978 to October 1984 are taken from Solar Geophysical Data Book. In absence of solar UV data for long period, a calibration curve between solar UV radiation and solar flare number (S.F.NO.) is drawn. (A straight line is obtained and correlation coefficient between two variables is 80%). The equation of straight line from least square principle becomes, UV flux = 0.2672 + 2.7578 × 10?5 × S.F.NO. From this equation UV flux values for long period are calculated from known values of solar flare numbers. O3 concentration of two Antarctic Survey Stations, Halley Bay (76? S, 27? W) and McMurdo (78? S, 166? E) are considered for analysis and following important results are obtained:
  1. Yearly variations of O3 concentrations and UV radiations are mainly controlled by their October concentrations.
  2. Correlation coefficient between O3 concentration and UV radiation is 62% for the month of October. For the other months it is poor.
  3. It is concluded that dramatic decrease of O3 concentration at Antarctica is independent of solar UV radiation and chemical processes are responsible for special depletion of O3.
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2.
H. Kiliç 《Solar physics》2009,255(1):155-162
The short-term periodicities in sunspot numbers, sunspot areas, and flare index data are investigated in detail using the Date Compensated Discrete Fourier Transform (DCDFT) for the full disk of the Sun separately over the rising, the maximum, and the declining portions of solar cycle 23 (1996 – 2006). While sunspot numbers and areas show several significant periodicities in a wide range between 23.1 and 36.4 days, the flare index data do not exhibit any significant periodicity. The earlier conclusion of Pap, Tobiska, and Bouwer (1990, Solar Phys. 129, 165) and Kane (2003, J. Atmos. Solar-Terr. Phys. 65, 1169), that the 27-day periodicity is more pronounced in the declining portion of a solar cycle than in the rising and maximum ones, seems to be true for sunspot numbers and sunspot area data analyzed here during solar cycle 23.  相似文献   

3.
The paper presents the effect of O3 depletion on different night airglow emission lines. Calculations based on chemical kinetics show that the airglow intensity of Na5893Å, O5577Å and OH band emissions will also be affected due to the depletion of O3 concentration. Intensity of Na5893Å is calculated theoretically for Halley Bay (76° S,27° W), British Antarctic Survey Station, during the period 1973 to 1984. It is concluded from the covariation of different emission lines that O5577Å and OH emissions also follow the same trend of variation. A study has been made to find the correlation between the depletion of O3 concentration and total solar flare numbers. Important results are as follows:
(i)  Depletion of O3 is oscillatory upto 7932 solar flare numbers. The average trend of variation of O3 concentration is downward, i.e., O3 is depleted with the increase of total solar flare numbers.
(ii)  Afterwards, it follows a upward trend. Possible explanation of such type variation is also presented.
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4.
Solar activity, such as flares and CMEs, affect the interplanetary medium, and Earth’s atmosphere. Therefore, to understand the Space Weather, we need to understand the mechanisms of solar activity. Towards this end, we use 1135 events of solar Hα flares and the positional data of sunspots from the archive of Solar Geophysical Data (SGD) for the period January–April, 2000 and compute the abnormal rotation rates that lead to high flare productivity. We report that the occurrence of 5 or more flares in a day in association with a given sunspot group can be defined as high flare productivity and the sunspots that have an abnormal rotation rates of ～4–10 deg day?1 trigger high flare productivity. Further, in order to compare the flare productivity expressed as the strength of the flux emitted, especially the soft X-ray (SXR) flares in the frequency range of 1–8 Å, we compute the flare index of SXR flares and find that 8 out of 28 active regions used in this study satisfy the requirement for being flare productive. This enables us to conclude that the high rotation rates of sunspots are an important mechanism to understand the flare productivity, especially numerical flare productivity that includes flares of all class.  相似文献   

5.
R. P. Kane 《Solar physics》2007,246(2):471-485
Many methods of predictions of sunspot maximum number use data before or at the preceding sunspot minimum to correlate with the following sunspot maximum of the same cycle, which occurs a few years later. Kane and Trivedi (Solar Phys. 68, 135, 1980) found that correlations of R z(max) (the maximum in the 12-month running means of sunspot number R z) with R z(min) (the minimum in the 12-month running means of sunspot number R z) in the solar latitude belt 20° – 40°, particularly in the southern hemisphere, exceeded 0.6 and was still higher (0.86) for the narrower belt > 30° S. Recently, Javaraiah (Mon. Not. Roy. Astron. Soc. 377, L34, 2007) studied the relationship of sunspot areas at different solar latitudes and reported correlations 0.95 – 0.97 between minima and maxima of sunspot areas at low latitudes and sunspot maxima of the next cycle, and predictions could be made with an antecedence of more than 11 years. For the present study, we selected another parameter, namely, SGN, the sunspot group number (irrespective of their areas) and found that SGN(min) during a sunspot minimum year at latitudes > 30° S had a correlation +0.78±0.11 with the sunspot number R z(max) of the same cycle. Also, the SGN during a sunspot minimum year in the latitude belt (10° – 30° N) had a correlation +0.87±0.07 with the sunspot number R z(max) of the next cycle. We obtain an appropriate regression equation, from which our prediction for the coming cycle 24 is R z(max )=129.7±16.3.  相似文献   

6.
W. Dean Pesnell 《Solar physics》2014,289(6):2317-2331
We describe using Ap and F10.7 as a geomagnetic-precursor pair to predict the amplitude of Solar Cycle 24. The precursor is created by using F10.7 to remove the direct solar-activity component of Ap. Four peaks are seen in the precursor function during the decline of Solar Cycle 23. A recurrence index that is generated by a local correlation of Ap is then used to determine which peak is the correct precursor. The earliest peak is the most prominent but coincides with high levels of non-recurrent solar activity associated with the intense solar activity of October and November 2003. The second and third peaks coincide with some recurrent activity on the Sun and show that a weak cycle precursor closely following a period of strong solar activity may be difficult to resolve. A fourth peak, which appears in early 2008 and has recurrent activity similar to precursors of earlier solar cycles, appears to be the “true” precursor peak for Solar Cycle 24 and predicts the smallest amplitude for Solar Cycle 24. To determine the timing of peak activity it is noted that the average time between the precursor peak and the following maximum is ≈?6.4 years. Hence, Solar Cycle 24 would peak during 2014. Several effects contribute to the smaller prediction when compared with other geomagnetic-precursor predictions. During Solar Cycle 23 the correlation between sunspot number and F10.7 shows that F10.7 is higher than the equivalent sunspot number over most of the cycle, implying that the sunspot number underestimates the solar-activity component described by F10.7. During 2003 the correlation between aa and Ap shows that aa is 10 % higher than the value predicted from Ap, leading to an overestimate of the aa precursor for that year. However, the most important difference is the lack of recurrent activity in the first three peaks and the presence of significant recurrent activity in the fourth. While the prediction is for an amplitude of Solar Cycle 24 of 65±20 in smoothed sunspot number, a below-average amplitude for Solar Cycle 24, with maximum at 2014.5±0.5, we conclude that Solar Cycle 24 will be no stronger than average and could be much weaker than average.  相似文献   

7.
The aim of the present study is to investigate the short-term periodicity in the solar radius measurements and to compare with the short periods in sunspot numbers, sunspot areas and flare index data. The spectral analysis of data sets covering a time interval from 26 February 2000 to 26 October 2007 during Solar Cycle 23 were made by using the Date Compensated Discrete Fourier Transform (DCDFT). The power spectrum of solar radius data corrected for the seeing effect gives an evident peak at 25.7 days with the amplitude of 0.034 arcsec, which is slightly different from the peaks of 26.2 and 26.7 days produced by sunspot numbers and sunspot areas data, respectively. Besides, the main peak of 25.7 days detected in the power spectrum of solar radius data is in agreement with the period of 25.5 days, suggested to be the fundamental period of the Sun by Bai and Sturrock (in Nature 350, 141, 1991).  相似文献   

8.
A “Solar Dynamo” (SODA) Index prediction of the amplitude of Solar Cycle 25 is described. The SODA Index combines values of the solar polar magnetic field and the solar spectral irradiance at 10.7 cm to create a precursor of future solar activity. The result is an envelope of solar activity that minimizes the 11-year period of the sunspot cycle. We show that the variation in time of the SODA Index is similar to several wavelet transforms of the solar spectral irradiance at 10.7 cm. Polar field predictions for Solar Cycles 21?–?24 are used to show the success of the polar field precursor in previous sunspot cycles. Using the present value of the SODA index, we estimate that the next cycle’s smoothed peak activity will be about \(140 \pm30\) solar flux units for the 10.7 cm radio flux and a Version 2 sunspot number of \(135 \pm25\). This suggests that Solar Cycle 25 will be comparable to Solar Cycle 24. The estimated peak is expected to occur near \(2025.2 \pm1.5\) year. Because the current approach uses data prior to solar minimum, these estimates may improve as the upcoming solar minimum draws closer.  相似文献   

9.
Results are presented from a study of solar radius measurements taken with the solar astrolabe at the TUBITAK National Observatory (TUG) over seven years, 2001–2007. The data series with standard deviation of 0.35 arcsec shows the long-term variational trend with 0.04 arcsec/year. On the other hand, the data series of solar radius are compared with the data of sunspot activity and H-α flare index for the same period. Over the seven year trend, we have found significant linear anti-correlations between the solar radius and other indicators such as sunspot numbers, sunspot areas, and H-α flare index. While the solar radius displays the strongest anti-correlation (−0.7676) with sunspot numbers, it shows a significant anti-correlation of −0.6365 with sunspot areas. But, the anti-correlation between the solar radius and H-α flare index is found to be −0.4975, slightly lower than others. In addition, we computed Hurst exponent of the data sets ranging between 0.7214 and 0.7996, exhibiting the persistent behavior for the long term trend. In the light of the strong correlations with high significance, we may suggest that there are a causal relationship between the solar radius and solar time series such as sunspot activity and H-α flare index.  相似文献   

10.
To understand better the variation of solar activity indicators originated at different layers of the solar atmosphere with respect to sunspot cycles, we carried out a study of phase relationship between sunspot number, flare index and solar radio flux at 2800 MHz from January 1966 to May 2008 by using cross-correlation analysis. The main results are as follows: (1) The flare index and sunspot number have synchronous phase for cycles 21 and 22 in the northern hemisphere and for cycle 20 in the southern hemisphere. (2) The flare index has a noticeable time lead with respect to sunspot number for cycles 20 and 23 in the northern hemisphere and for cycles 22 and 23 in the southern hemisphere. (3) For the entire Sun, the flare index has a noticeable time lead for cycles 20 and 23, a time lag for cycle 21, and no time lag or time lead for cycle 22 with respect to sunspot number. (4) The solar radio flux has a time lag for cycles 22 and 23 and no time lag or time lead for cycles 20 and 21 with respect to sunspot number. (5) For the four cycles, the sunspot number and flare index in the northern hemisphere are all leading to the ones in the southern hemisphere. These results may be instructive to the physical processes of flare energy storage and dissipation.  相似文献   

11.
The M7.7 solar flare on July 19, 2012, is the most dramatic example of a “Masuda” flare with a well-defined second X-ray above-the-loop-top source. The behavior of the system of loops accompanying this flare has been studied comprehensively by Liu et al. based on Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) data. We have performed spectroscopic and filter observations of the Hα loops in this flare with the Large Solar Vacuum Telescope. The basic physical parameters in the loops of this peculiar flare generally coincide with the known data in Hα loops. However, the electron density, 1011 cm?3, and the integrated disk-center continuum intensity, 12%, are quite high, given that the observations were obtained almost 3 h after the flare onset.We have estimated the ascending velocity of the loop arcade (~3.5 km s?1) and the height difference between the Hα and 94 Å loops (~2 × 104 km).  相似文献   

12.
In this work, the evolution of the relationship between Solar Cycle Length of solar cycle n (SCL n ) and Solar Cycle Amplitude of the solar cycle n+1 (SCA n+1) is studied by using the R Z and R G sunspot numbers. We conclude that this relationship is only strongly significant in a statistical sense during the first half of the historical record of R Z sunspot number whereas it is considerably less significant for the R G sunspot number. In this sense we assert that these simple lagged relationships should be avoided as a valid method to predict the following solar activity amplitude.  相似文献   

13.
A study on north–south (N–S) asymmetry of different solar activity features (DSAF) such as solar proton events, solar active prominences [total, low (?40°) and high (?50°) latitudes], Hα flare indices, soft X-ray flares, monthly mean sunspot areas and monthly mean sunspot numbers carried out from May 1996 to October 2008. Study shows a southern dominance of DSAF during this period. During the rising phase of the cycle 23 the number of DSAF approximately equals on both, the northern and the southern hemispheres. But these activities tend to shift from northern to southern hemisphere during the period 1998–1999. The statistical significance of the asymmetry time series using a χ2-test of goodness of fit indicates that in most of the cases the asymmetry is highly significant, meaning thereby that the asymmetry is a real feature in the N–S distribution of DSAF.  相似文献   

14.
R. P. Kane 《Solar physics》2008,249(2):369-380
The sunspot number series at the peak of sunspot activity often has two or three peaks (Gnevyshev peaks; Gnevyshev, Solar Phys. 1, 107, 1967; Solar Phys. 51, 175, 1977). The sunspot group number (SGN) data were examined for 1997 – 2003 (part of cycle 23) and compared with data for coronal mass ejection (CME) events. It was noticed that they exhibited mostly two Gnevyshev peaks in each of the four latitude belts 0° – 10°, 10° – 20°, 20 ° – 30°, and > 30°, in both N (northern) and S (southern) solar hemispheres. The SGN were confined to within latitudes ± 50° around the Equator, mostly around ± 35°, and seemed to occur later in lower latitudes, indicating possible latitudinal migration as in the Maunder butterfly diagrams. In CMEs, less energetic CMEs (of widths < 71°) showed prominent Gnevyshev peaks during sunspot maximum years in almost all latitude belts, including near the poles. The CME activity lasted longer than the SGN activity. However, the CME peaks did not match the SGN peaks and were almost simultaneous at different latitudes, indicating no latitudinal migration. In energetic CMEs including halo CMEs, the Gnevyshev peaks were obscure and ill-defined. The solar polar magnetic fields show polarity reversal during sunspot maximum years, first at the North Pole and, a few months later, at the South Pole. However, the CME peaks and gaps did not match with the magnetic field reversal times, preceding them by several months, rendering any cause – effect relationship doubtful.  相似文献   

15.
Kakad  B. 《Solar physics》2011,270(1):393-406
The purpose of the present study is to develop an empirical model based on precursors in the preceding solar cycle that can be used to forecast the peak sunspot number and ascent time of the next solar cycle. Statistical parameters are derived for each solar cycle using “Monthly” and “Monthly smoothed” (SSN) data of international sunspot number (R i). Primarily the variability in monthly sunspot number during different phases of the solar cycle is considered along with other statistical parameters that are computed using solar cycle characteristics, like ascent time, peak sunspot number and the length of the solar cycle. Using these statistical parameters, two mathematical formulae are developed to compute the quantities [Q C] n and [L] n for each nth solar cycle. It is found that the peak sunspot number and ascent time of the n+1th solar cycle correlates well with the parameters [Q C] n and [L] n /[S Max] n+1 and gives a correlation coefficient of 0.97 and 0.92, respectively. Empirical relations are obtained using least square fitting, which relates [S Max] n+1 with [Q C] n and [T a] n+1 with [L] n /[S Max] n+1. These relations predict a peak of 74±10 in monthly smoothed sunspot number and an ascent time of 4.9±0.4 years for Solar Cycle 24, when November 2008 is considered as the start time for this cycle. Three different methods, which are commonly used to define solar cycle characteristics are used and mathematical relations developed for forecasting peak sunspot number and ascent time of the upcoming solar cycle, are examined separately.  相似文献   

16.
A major solar flare on 15 November, 1991 produced a striking perturbation in the position and shape of the sunspot related most closely to the flare. We have studied these perturbations by use of the aspect-sensor images from the Soft X-ray Telescope on board YOHKOH, and with ground-based data from the Mees Solar Observatory. The perturbation occurred during the impulsive phase of the flare, with a total displacement on the order of 1 arc sec. The apparent velocity of approximately 2 km s–1 exceeds that typically reported for sunspot proper motions even in flare events. We estimate that the magnetic energy involved in displacing the sunspot amounted to less than 4 × 1030 ergs, comparable to the radiant energy from the perturbed region. Examination of the Mees Observatory data shows that the spot continued moving at lower speed for a half-hour after the impulsive phase. The spot perturbation appears to have been a result of the coronal restructuring and flare energy release, rather than its cause.  相似文献   

17.
Using the smoothed time series of maximum CME speed index for solar cycle 23, it is found that this index, analyzed jointly with six other solar activity indicators, shows a hysteresis phenomenon. The total solar irradiance, coronal index, solar radio flux (10.7?cm), Mg?ii core-to-wing ratio, sunspot area, and H?? flare index follow different paths for the ascending and the descending phases of solar cycle?23, while a saturation effect exists at the maximum phase of the cycle. However, the separations between the paths are not the same for the different solar activity indicators used: the H?? flare index and total solar irradiance depict broad loops, while the Mg?ii core-to-wing ratio and sunspot area depict narrow hysteresis loops. The lag times of these indices with respect to the maximum CME speed index are discussed, confirming that the hysteresis represents a clue in the search for physical processes responsible for changing solar emission.  相似文献   

18.
Observational evidence and theoretical predictions of the response of ozone to solar variations are reviewed. Short-term solar proton effects, possible effects of galactic cosmic rays modulated by the Sun, and the effects of 27-day solar rotation and 11-year solar cycle variations are discussed. Solar proton effects on HO x chemistry in the mesosphere and NO x chemistry in the stratosphere with resulting catalytic destruction of O3 help validate present day photochemical models. If there is an 11-year solar cycle variation in global ozone, the large dynamical effects at individual locations and the lack of good global coverage of ground based and in situ measurements can disguise it. Recently, with the global coverage of satellites, it has become possible to accurately determine global mean ozone. It has been found that variations in global mean ozone filtered for seasonal variations are highly correlated with variations of the 10.7 cm solar activity index and that global mean ozone responds rapidly to solar activity index variations. Photochemical models indicate that the observed 3% variations in global mean ozone over the solar cycle can be accounted for by solar UV variations which are not inconsistent with recent solar measurements.Proceedings of the 14th ESLAB Symposium on Physics of Solar Variations, 16–19 September 1980, Scheveningen, The Netherlands.  相似文献   

19.
J. Javaraiah 《Solar physics》2013,287(1-2):197-214
Using the Solar Optical Observing Network (SOON) sunspot-group data for the period 1985?–?2010, the variations in the annual mean equatorial-rotation rates of the sunspot groups are determined and compared with the known variations in the solar equatorial-rotation rates determined from the following data: i) the plasma rotation rates at 0.94R⊙,0.95R⊙,…,1.0R⊙ measured by the Global Oscillation Network Group (GONG) during the period 1995?–?2010, ii) the data on the soft-X-ray corona determined from Yohkoh/SXT full-disk images for the years 1992?–?2001, iii) the data on small bright coronal structures (SBCS) that were traced in Solar and Heliospheric Observatory (SOHO)/EIT images during the period 1998?–?2006, and iv) the Mount Wilson Doppler-velocity measurements during the period 1986?–?2007. A large portion (up to ≈?30° latitude) of the mean differential-rotation profile of the sunspot groups lies between those of the internal differential-rotation rates at 0.94R⊙ and 0.98R⊙. The variation in the yearly mean equatorial-rotation rate of the sunspot groups seems to be lagging behind that of the equatorial-rotation rate determined from the GONG measurements by one to two years. The amplitude of the GONG measurements is very small. The solar-cycle variation in the equatorial-rotation rate of the solar corona closely matches that determined from the sunspot-group data. The variation in the equatorial-rotation rate determined from the Mount Wilson Doppler-velocity data closely resembles the corresponding variation in the equatorial-rotation rate determined from the sunspot-group data that included the values of the abnormal angular motions (>?|3°|?day?1) of the sunspot groups. Implications of these results are pointed out.  相似文献   

20.
This article is an update of a study (Tapping and Valdès in Solar Phys. 272, 337, 2011) made in the early part of Cycle 24 using an intercomparison of various solar activity indices (including sunspot number and the 10.7 cm solar radio flux), in which it was concluded that a change in the relationship between photospheric and chromospheric/coronal activity took place just after the maximum of Cycle 23 and continued into Cycle 24. Precursors (short-term variations) were detected in Cycles 21 and 22. Since then the sunspot number index data have been substantially revised. This study is intended to be an update of the earlier study and to assess the impact of the revision of the sunspot number data upon those conclusions. This study compares original and revised sunspot number, total sunspot area, and 10.7 cm solar radio flux. The conclusion is that the transient changes in Cycles 21 and 22, and the more substantial change in Cycle 23, remain evident. Cycle 24 shows indications that the deviation was probably another short-term one.  相似文献   

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