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[en] This study aims at investigating surface magnetic flux participation among different types of magnetic features during solar cycle 24. State-of-the-art observations from SDO/HMI and Hinode/SOT are combined to form a unique database in the interval from April 2010 to October 2015. Unlike previous studies, the statistics presented in this paper are feature-detection-based. More than 20 million magnetic features with relatively large scale, such as sunspot/pore, enhanced and quiet networks, are automatically detected and categorized from HMI observations, and the internetwork features are identified from SOT/SP observations. The total flux from these magnetic features reaches 5.9×1022 Mx during solar minimum and 2.4×1023 Mx in solar maximum. Flux occupation from the sunspot/pore region is 29% in solar maximum. Enhanced and quiet networks contribute 18% and 21% flux during the solar minimum, and 50% and 9% flux in the solar maximum respectively. The internetwork field contributes over 55% of flux in the solar minimum, and its flux contribution exceeds that of sunspot/pore features in the solar maximum. During the solar active condition, the sunspot field increases its area but keeps constant flux density of about 150G, while the enhanced network follows the sunspot number variation showing increasing flux density and area, but the quiet network displays decreasing area and somewhat increasing flux density of about 6%. The origin of the quiet network is not known exactly, but is suggestive of representing the interplay between mean-field and local dynamos. The source, magnitude and possible importance of ‘hidden flux’ are discussed in some detail. (paper)
[en] Study of variations in solar activity parameters has its importance in understanding the underlying mechanisms of space weather phenomena and space climate variability. We have used the already observed data of solar parameters viz. sunspot numbers, F10.7 cm index and Lyman alpha index recorded for last seventy years (1947–2017). We have applied the Hodrick Prescott filtering method to bifurcate each time series into cyclic and trend parts. The cyclic part of each time series was used to analyse the persistence while the trend part was used to obtain the input data for the study of future predictions. Further, the cyclic component of each parameter was analysed by using the rescaled range analysis and the value of Hurst exponent was obtained for sunspot numbers, F10.7 cm index and Lyman alpha index as 0.90, 0.93 and 0.96 respectively. By using the simplex projection analysis on the values of amplitude and phase of the trend component of each time series, we have reconstructed the future time series representing solar cycles 25 and 26. When extrapolated further in time, the reconstructed series provided the maximum values of sunspot numbers as and ; maximum values of F10.7 cm index were and and Lyman alpha index were and respectively for solar cycles 25 and 26. In our analysis we have found that the solar cycle 25 will start in the year 2021 (January) and will last till 2031 (February) with its maxima in year 2024 (February) while the solar cycle 26 will start in the year 2031 (March) with its maxima in 2036 (June) and will last till the year 2041 (February). We have also compared the activities of solar cycles 5 and 6 (Dalton minima periods) to solar cycles 25 and 26 and have observed that the other solar minimum is underway.
[en] Wave energy up conversion of high frequency plasma wave in presence of low frequency plasma wave are studied in both space and laboratory plasma. In the ionosphere different forms of free energy sources are coexisting and energy exchange process takes place among plasma waves and particles. Through plasma maser effect ionospheric plasma particles may be transferred energy nonlinearly to high frequency mode through a modulated electric field in the presence of electron density gradients. In this paper it has been explained how energy from drift wave is transferred to non-resonant ion sound wave. Including plasma inhomogeneity effect in our model the growth rate of ion sound wave in the Earth’s ionosphere in presence of drift wave turbulence estimated using observational data
[en] Space weather is well recognized by the various solar activities and their cycles. The emission line corona (spectral line 530.3 ) and its distribution reflect the solar activity that is caused by the ecumenical magnetic field. The acknowledgement of this paramountcy cyclic studied (1954 to 2016) under the spectral line 530.3 and its cycle by Markov chain technique. In utilizing of Markov there is periodic behaviour observed in process of Markov chain in the coronal index (CI) solar cycle, with associated El Nino Southern Oscillation (ENSO). The strongest relationship (0.98) is found between the transition matrix of CI and ENSO total cycles using the 2-dimensional correlation. Moreover, the validity of the Markov chain analyses is endorsed by dependency and stationary test of CI and ENSO data. Results indicate that CI can define the solar geomagnetic effect on ENSO as a solar activity like sunspot activity. Similarly, return periods of both the data sets demonstrate the highest number of visits in state 3. Since CI and sunspots are associated with performing the space climate. The individual relationship of CI to the earth’s climatic parameter may open the new directions to understand the climate variation.
[en] : Sunspots occur due to magnetic disturbances on the surface of the sun. The sunspot activity effects weather on earth and also affect the earth temperature. In this research paper, various spectral estimation techniques for estimation of universal cyclic behavior of sunspot numbers are discussed. Spectral analysis has been based on two different approaches, namely parametric and non-parametric estimation. The performance of various parametric and non-parametric spectral estimation methods has been compared and frequency of occurrence of sunspots is calculated. MATLAB computer simulations have been extensively used for various estimator settings to arrive at correct results. The results show that the parametric spectral estimation techniques show better and consistent performance as compared to non-parametric spectral estimation techniques. (author)
[en] The St. Patrick’s Day phenomenon is a geomagnetic storm that deserves serious discussion because of its intensity and effectiveness. This study focuses on the St. Patrick’s Day storm on March 17, 2015, which is the first big storm of the 24th solar cycle. The data obtained from various spacecrafts observing the ionosphere reveal the reputation and the strength of the storm. The author tries to discuss the event as a whole with all its parameters. Variables of the study are the solar wind parameters and zonal geomagnetic indices. Models with solar wind pressure, proton density and magnetic field may aid in making the dynamic structure of the phenomenon more understandable. The obtained models are able to give the reader an idea of the results even if the storm prediction percentage is low. The author has endeavored to obey the cause–effect relationship without ignoring the physical principles when establishing mathematical models. Despite the fact that the relations between variables have poor correlation or have low statistical significance, in order to introduce the physical point of view they have not been ignored. This study puts forth a new mathematical perspective by discussing and visualizing what happened in the phenomenon. . s
[en] Annually laminated sediments (varves) form in particular depositional settings, e.g., where seasonal climate produces fluctuations in runoff volume; variations in runoff affect the amount and type of sediment delivered to a catchment. Prior studies confirm that variations in selected varve traits correlate with inter-annual climate signals. In some locations, solar activity also appears to be expressed in varve characteristics, either through a direct effect or indirectly via influence of solar activity on climate. Evidence from proglacial Iceberg Lake, Alaska, indicates that solar activity may have directly contributed to varve deposition. A varve thickness sequence is compared to sunspot observations from 1610-1995 CE. Maunder and Dalton minima are clearly expressed in a varve power spectrogram; varve signal amplification beginning ca. 1950s CE coincides with increasing activity evident in a sunspot spectrogram, features that are only vaguely discernible in the raw time-series plots. Spectral relationships at sunspot periodicities are consistent with direct solar forcing of varve thickness, independent of any effect solar activity might otherwise have on climate. Simulations based on a meltwater model indicate that direct forcing could result from amplified ultraviolet (UV) emission during solar maxima, combined with lower UV albedo of glacial ice. The plausible forcing mechanism bolsters epistemology for concluding a cause-effect relationship: solar variability likely contributed directly to inter-decadal patterns in Iceberg Lake varve thicknesses. The putative effect could be enhanced at higher latitudes, where Earth’s atmosphere absorbs less of the UV energy emitted by the Sun; periods of lowered ozone concentration near the poles would exacerbate the natural abetting UV phenomena, potentially linking human activity to recent and accelerated polar ice cap melting. (author)
[en] We are very aware of the importance of the ozone layer, without which life on the Earth would not have evolved in the way it has. Solar storms carry energetic protons into the Earth’s upper atmosphere, where they boost production of nitrogen oxides which are known as ozone killers and which ultimately increase ultraviolet (UV) radiations. In the present study, we estimate the effects of solar energetic protons during super storms (Dst index < –300 nT over the total ozone column for the last 32 yr. We select a total of seven super storm events that occurred during solar cycles 22–24 (for the last 32 yr) having Dst index < –300 nT. To that end, we apply superposed epoch analysis (SEA) to verify the impact of storm events on the quantitative variation of total ozone column and on UV radiations during super storm events. After completing the empirical analysis, we conclude that the ozone column gets depleted significantly (22±6.8%) as proton density increases during super storm events and this decrement in the ozone level is further responsible for a substantial increase (26±11.2%) in peak UV radiation intensities. (paper)
[en] The varying solar output is affected by the Sun’s activity and associated phenomena. Predictions of solar and geomagnetic activity are important for various technologies, including the operation of low-earth-orbiting satellites, electric power transmission grids, geophysical exploration and high-frequency radio communications. Annual averages of geomagnetic activity in cycle 23 were found to be large in comparison with other cycles. The dramatic variability from one cycle to the other in these parameters gives us unique opportunity to understand the physics of various associated phenomena. In this paper, we have analysed the solar cycles 22 and 23 and compared them with solar cycle 24 on the basis of 10.7 radio flux, sunspot number (Rz), solar flare index, cosmic ray intensity and interplanetary and geomagnetic parameters. (author)