- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Prediction of declining solar activity trends during solar cycles 25 and 26 and indication of other solar minimum
摘要： 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 ?ltering 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 89 ± 9 and 78 ± 7; maximum values of F10.7 cm index were 124 ± 11 and 118 ± 9 and Lyman alpha index were 4.61 ± 0.08 and 4.41 ± 0.08 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.
关键词： Rescale range analysis,Sunspot numbers,Solar activity,solar minimum,Hurst exponent,Simplex projection analysis
更新于2025-09-23 15:22:29
-
Identification of photospheric activity features from SOHO/MDI data using the ASAP tool
摘要： The variation of solar irradiance is one of the natural forcing mechanisms of the terrestrial climate. Hence, the time-dependent solar irradiance is an important input parameter for climate modelling. The solar surface magnetic field is a powerful proxy for solar irradiance reconstruction. The analyses of data obtained with the Michelson Doppler Imager (MDI) on board the SOHO mission are therefore useful for the identification of solar surface magnetic features to be used in solar irradiance reconstruction models. However, there is still a need for automated technologies that would enable the identification of solar activity features from large databases. To achieve this we present a series of enhanced segmentation algorithms developed to detect and calculate the area coverages of specific magnetic features from MDI intensitygrams and magnetograms. These algorithms are part of the Automated Solar Activity Prediction (ASAP) tool. The segmentation algorithms allow us to identify the areas on the solar disk covered by magnetic elements inside and outside boundaries of active regions. Depending on their contrast properties, magnetic features within an active region boundary are classified as sunspot umbra and penumbra, or faculae. Outside an active region boundary magnetic elements are identified as network. We present the detailed steps involved in the segmentation process and provide the area coverages of the segmented MDI intensitygrams and magnetograms. The feature segmentation was carried out on daily intensitygrams and magnetograms from April 21, 1996 to April 11, 2011. This offers an exciting opportunity to undertake further investigations that benefit from solar features segmentations, such as solar irradiance reconstruction, which we plan to investigate in the future.
关键词： Magnetogram,Sunspot,Solar image processing,Spectral irradiance,Active region
更新于2025-09-04 15:30:14