The Relationship Between In-situ Properties And Source Regions Of Soalr Wind And Its Evolution With Heliocentric Distance

The origin and heating acceleration of solar wind are two unsolved problems in solar physics.Studying the source region of solar wind and its propagation in interplanetary space will help us to improve our understanding of these two problems.Existing work only focus on sources of solar wind,or the solar wind properties in different heliocentric distance,but from the same source of solar wind with the evolution of the heliocentric distance,originated from the same source region of the solar wind properties dependence on source’s evolution,as well as from the same source area close to the time(days)the evolution of the nature of the solar wind with the heliocentric distance is still lack of research.This paper focuses on combining the the evolution of solar wind in-situ properties with heliocentric distance and the characteristics of source regions.This work could improve our understanding of important questions about the origins of the solar wind and the heating and acceleration mechanisms underlying the initial solar wind.Our work will combine in-situ solar wind data from the PSP and the ACE/Wind satellite at Lagrange 1,using the "two-step ballistic method",using PFSS(Potential Field Source Surface)model to trace the solar wind back to the solar surface,and then combined with solar EXTREME ultraviolet images and optical sphere magnetic field observation data,the region where the foot points are located is divided into coronal hole region and active region.The evolution of solar wind properties from different source regions with heliocentric distance is studied.The first work of this paper is to compare the solar wind from coronal holes and active regions with the heliocentric distance.We collected the solar wind data of PSP from November 2018 to November 2021,divided the above solar wind into coronal hole solar wind and active solar wind according to the source region type,and analyzed the parameter evolution with heliocentric distance.We find that the density,magnetic field and pressure of solar wind decrease with the increase of heliocentric distance,and the entropy of solar wind increases with the increase of heliocentric distance.In different heliocentric distances,the wind speed,proton temperature and entropy of coronal hole wind are generally higher than those of active zone wind,while the density,magnetic field and pressure of active zone wind are higher than those of coronal hole wind.The coronal hole wind is about 450 km/s outside 100 solar radii,and the solar wind is about 350 km/s in active regions.The second work of this paper is to analyze the dependence of solar wind parameters on the evolution of the source region of a long-lived and large-scale equatorial coronal hole,and to study the characteristics of solar wind originating from this large-scale coronal hole at different heliocentric distances at similar periods of source evolution.We found that the lower the brightness of coronal hole,the greater the net magnetic flux and magnetic field imbalance,the higher the speed of solar wind,the longer the duration of high-speed flow,and the more obvious the density and magnetic field compression effect of the flow interface of fast and slow wind.During the CR2210 Carrington,we combined the PSP and ACE datas to investigate the difference of solar wind properties at 0.3 AU and 1 AU from the same coronal hole at a similar time.We find that the SIR structure(velocity shear,density compression,magnetic field pressure peak)at 1 AU is more sharp than that at 0.3 AU.This indicates that the SIR structure gradually increases with the solar wind radial propagation within 1 AU.The fast solar wind from CR2210 coronal hole lasts 3-4 days longer at 0.3 AU than that at 1 AU,and the longitude projection of the high-speed wind detected by PSP is 38 degrees larger than that detected by ACE.We believe that the main reason for this result may be the evolution of the source region,which means that the nature of the solar wind generated by the large-scale coronal holes can also change greatly in several days.The results show that the properties of the solar wind are closely related to the characteristics of the source region,and there are significant differences between the properties of the solar wind in the coronal hole region and the active region at different heliocentric distances.And the nature of the solar wind produced by the same largescale and long-lived coronal hole can also change dramatically within a few days.This paper deepens our understanding of the properties of solar wind from different source regions at different heliocentric distances and enhances our understanding of the dependence of solar wind properties and source region characteristics.