Analysis Of The Characteristics Of The Solar Cycle Based On The New Version Of The Sunspot Number Data

As the nearest star to the earth,the activity of the sun is highly related to human life.The periodic change of the sun is an important factor affecting space weather and earth's climate.Generally,we believe that the periodic change of sunspot number represents the change of solar activity cycle,and the intensity of solar activity presents a periodic change characteristic with the fluctuation of sunspot number.The Solar Influences Data Analysis Center(SIDC)issued a new version(version 2)of the sunspot number data in July 2015.It is employed in our work.The shape of the solar cycles.Most of the time,the shape of sunspot cycles has been studied with single-peak functions.But in fact,the shape of sunspot cycles is more complicated than such a single-peak flowing curve.And a lot of research said that the shape of the sunspot cycle is a double-peak curve.A functional form using a binary mixture of Gaussian functions has been used here to study the shape of the sunspot cycle.Examinations of the goodness of fit show that the binary mixture of Gaussian functions gives a very perfect fit of cycle shape.The fitting effects at peaks are also investigated.Features of the sunspot cycle shape are inspected based on the fitting by the binary mixture of Gaussian functions,that says the function keeps the solar-cycle characteristics well.The 13-month smoothed monthly sunspot number from the new version is used for the first time to research the relations among the feature parameters of solar cycles under the bimodal distribution for the modern era cycles(10–23),and,their physical implications are discussed.These relations are utilized to predict the maximum amplitude of solar cycle 25.Cycle 25 is predicted to start in October 2020 and reach its maximum amplitude of 168.5 ± 16.3 in October 2024,thus,it should be stronger than cycle 24 but weaker than cycle 23.The N–S asymmetry(the north–south hemispheric asymmetry)of sunspot areas for each of the cycles 7–24 have been investigated,and a trend of a long-term characteristic timescale of about eight cycles is inferred,which is confirmed again by studying the fitted lines of the yearly values of the N–S asymmetry of sunspot numbers and sunspot group numbers at solar cycle 24.Then,a periodic behavior of about 12 solar cycles is found in the cumulative counts of yearly sunspot areas for each of the cycles 7–24.Nevertheless,the cumulative counts of sunspot numbers and sunspot group numbers for cycle 24 have different behaviors.Moreover,the dominant hemispheres for cycles 7–23 show a trend of a long-term characteristic timescale of about 12 cycles.However,we cannot determine the dominant hemisphere of cycle 24,as these three parameters give different results for the dominant hemisphere.Cycle 24 is a particular solar activity cycle,as sunspot areas suggest a long characteristic timescale of about 12-cycle length,while sunspot numbers and sunspot group numbers support an eight-cycle period of the N–S asymmetry.