Study On Characteristics Of Particle Precipitation Of Typical Aurora Morphology Of Night Aurora Oval Based On Spatial Orientation

Aurora particles play an indispensable role in the coupling of magnetosphere and ionosphere.Most of the nighttime aurora is closely related to the occurrence of auroral substorms,so it is important to study the characteristics of nightside auroral precipitation for understanding the space environment of polar regions and predicting space weather.In this paper,at first,using the all-sky images of the Chinese Yellow River Station,we develop a method of spatial positioning for the pixels in all-sky image,which is based on the position of stars in all-sky images.Secondly,using the all sky images of Iceland Station and Zhongshan Station,we study the synoptic distribution of nightside aurora in different wavelengths,and divide the nightside auroral oval into different active regions based on the characteristics of auroral spectrum and morphology.At last,we combine all-sky images with the particle data of satellite observation to analyze the characteristics of auroral precipitation particles for different typical nightside auroral forms.The main results are summarized as follows:1.Spatial positioning of the all sky imageUsing the all sky images of Yellow River Station,we develop a method of spatial positioning for the pixels in all sky image,which is based on the position of the stars.Through this method,the parameters of all sky image(zenith pixel position in the image,geographic orientation,the relationship between the imaging radius and the zenith)can be determined.The corresponding relationship between the aurora arc and inverted "V" structure is used to verify the parameters of the all sky image obtained by the star-point calibration method.The results show that the inverted "V" structure width(60±6 km,102±6 km)of the crossing of the satellite is almost the same as that of the aurora arc width(64.7±7 km,111.6±7 km)observed by the all-sky aurora imager,which indicates that the star-point calibration method of all-sky aurora image parameters proposed in this paper is effective and accurate.2.Multiple-wavelength distributions of nightside auroraUsing the multiple-wavelength all-sky images of Iceland station in Arctic and Zhongshan station in Antarctic,we get the multiple-wavelength synoptic distributions of nightside aurora for the first time.In the nightside auroral oval,there are two peak on pre-midnight and post-midnight oval,and the magnetic local time of the peak is 2100 MLT and 0300 MLT,respectively.The pre-midnight peak is consistent with the observation of ultraviolet imager aboard satellites,but the post-midnight peak is not shown in the observation result of satellites.3.Characteristics of nightside typical aurora precipitation particlesOn the nightside,the aurora arc,west-traveling surge,pulsating aurora and premidnight diffuse aurora have integrated energy flux peaks at 50eV-1keV and 1-20 keV,but the energy flux peaks at 50eV-1keV are all lower than 1-20 keV,and the peak energy fluxes of ions are all lower than those of electrons.It indicates that in the aurora particle precipitation,electron precipitation plays a dominant role in the 50eV-20 keV energy range,and the dominant electron energy is concentrated in the 1-20 keV.The most interesting phenomenon is that both the low latitude side and the high latitude side of the electron energy flux peak area have a peak of ion energy flux,and the high latitude side of the aurora arc event has the peak of ion energy flux in the range of 1-20 keV,while the west-traveling surge has the peak of 50eV-1keV in the high latitude side,and in the low latitude side we have the opposite result.However,the west-traveling surge in the high latitude region of the aurora oval is similar to that in the low latitude region.The particle precipitation energy spectrum shows that there are ion peaks on both sides of the peak of the electron energy spectrum,with high ion energy on the low latitude side and low ion energy on the high latitude side.For the phenomenon that the low latitude side ions and the electron energy flux peaks appear successively in the aurora particle precipitation area,we judge that it is related to the Harang discontinuity,but the phenomenon that the high latitude side electrons and the electron energy flux peaks appear alternately in the aurora particle deposition area needs further study.Low-energy ion structures of about 100 eV were found to be associated with pulsating auroral blocks in the settling particles of pulsating auroras.