The Relationship Between The Line-of-sight Electric Current Density Distribution Of The Photosphere And The Position Of The Flare Ribbons

Long-term observations and studies have shown that the flare eruptions are closely related to the current structure of the active region.Therefore,choosing a suitable method to calculate the line-of-sight current density distribution of the photosphere has great significance for predicting the location and shape of the flare eruption.Based on the high-resolution photosphere vector magnetic field data obtained by SDO/HMI,we calculated the line-of-sight current density during the explosion of an X2.2-class flare in the Active Region AR11158 on February 15,2011 using the differential and integral algorithms of Ampere's law.The results show that there is a significant difference in the current density calculated by the two algorithms of Ampere's law.The reason for the significant difference is probably due to the unavoidable influence from random noise exists in the vector magnetic field measurement.The current density obtained by the differential algorithm are more affected by random noise.When the integral path is expanded to two loops,the current density is less affected by random noise than one integral loop,and the fine structure of the current is also very clear.When the radius of the integral loop is continued to be enlarged,the current density distribution diagram is clearer than the two loops,but some of the fine structure in the current is obviously distorted.The results imply that the dispersion of the measured value will be increased when using the differential algorithm of Ampere's law to calculate the line-of-sight current density due to the influence of random errors,which lead to the current density not as good as the loop integral method.With the expansion of the integral loop,the current density distribution diagram will become more clearer.This shows that the influence of random noise can be effectively reduced by expanding the radius of the integral loop.However,the integral loop is not as expanded as possible,we should choose a suitable integral path according to different resolutions.Only in this way,a clear current density distribution diagram can be obtained and the fine structure of the current can be retained completely.In this article,we obtained the best current density distribution by using the integral algorithm of Ampere's law when the radius of the integral loop is expanded to two loops.In order to verify the validity and rationality of our calculation method,we also compare the line-of-sight current density distribution calculated by the two integral loops with the similar time flare image obtained by SDO/AIA in 304 ? band and 1700 ? band.The result shows that the flare ribbons and the current ribbons not only corresponding roughly in positions,but also extremely similar in shapes.This further verifies the rationality and significance of our current density calculation method.The first chapter of this paper is the introduction,which mainly introduces the layered structure of the sun and the phenomenon of solar activity.Chapter 2 mainly introduces solar flares and currents in the active area of flares.Chapter 3 mainly introduces the measurement of vector magnetic field and the calculation of current in the solar active region.Chapter 4 is the main work of our thesis,that is,using the differential algorithm and the integral algorithm of Ampere's law to calculate the lineof-sight current density associated with an X2.2-class flare in Active Region AR11158.Through comparison and analysis,we get a more suitable calculation method for calculating current density.Chapter 5 is summary and outlook.