Subjects: Astronomy >> Astrophysical processes submitted time 2023-10-18 Cooperative journals: 《天文研究与技术》
Abstract： As an important basis for predicting solar activity, the McIntosh classification of sunspots is used by more and more international institutions and astronomical institutes because some categories are closely related to flare eruption. With the rapid increase in the amount of data, automatic McIntosh classification of sunspots has become an urgent need. Using the 720s-SHARP series data products provided by SDO/ HMI and SRS files from NOAA as images and labels for McIntosh classification, this paper first augmented valid samples of a complete solar cycle (time span of 12 years) and cleaned data to establish the sunspot database newSharp on the basis of the Sharp database with only 7-year data. Secondly, in view of the characteristics of sunspot images, a series of preprocessing operations such as data allocation by active region number were taken, and proved its rationality and necessity. Finally, four classical classification neural network models in CNN were used to compare Sharp and newSharp for McIntosh classification experiments. The results show that compared with Sharp, newSharp not only has a significant increase in the amount of data, but also has better weighted F1 score of most categories by augmenting valid samples and cleaning invalid samples. Besides, the weighted F1 score of categories with a small number from newSharp even has achieved a breakthrough of 0. Over all, the weighted F1 score of McIntosh-p improved the most, which greatly verifies the effectiveness of establishing a complete and reliable database and proves the rationality of using scientific and reasonable experimental methods. Thus it is able to better automatedly realize the end-to-end McIntosh classification tasks of sunspot images that are actually observed.
Subjects: Astronomy >> Astrophysical processes submitted time 2021-01-15 Cooperative journals: 《天文研究与技术》
Abstract：磁场是太阳爆发活动的根本驱动力，高精度实时偏振测量是实现磁场测量的常用方法。然而常用的波片式测量方法需要进行多次测量，且存在机械旋转结构，易导致仪器抖动，降低测量精度；波片旋转或切入切出也会导致测量时间较长。目前，基于DKDP晶体和波片的太阳大气偏振测量周期较长，实时性不高，无法应用于快速变化的太阳活动磁场探测。基于以上背景，本论文提出了一种基于双DKDP晶体原理的太阳大气实时偏振探测技术，采用两片快轴方向不同的DKDP晶体，通过外加不同电压进行快速相位延迟变化，实现对入射太阳光的偏振调制，获取太阳大气偏振斯托克斯矢量。相较于传统旋转波片与DKDP晶体相结合的方法，本论文提出方法可将单次偏振调制速率从数秒提升到毫秒级，极大地提升了太阳磁场测量实时性。仿真分析结果表明：本文提出方法测量精度达到2×〖10〗^(-3)，单波长点测量时间分辨率提升了20倍以上，可以实现对太阳磁场偏振信息的实时精确测量。
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