Study On Thermospheric Neutral Wind During Substorms Based On FPI

The wind has always been a key factor in the study of the upper atmosphere,and it has an interaction with the other three parameters(temperature,pressure and composition)in the upper atmosphere.The thermosphere is an important region of the upper atmosphere,where there are many kinds of neutral and ionizing components,as well as many kinetic processes resulting in the coupling of energy.Input of high-energy particles and geomagnetic field directly affect the coupling of ionospheric ions and neutral particles in the thermosphere.It is found that the motion of ions and neutral particles in the presence of aurora are strongly coupled,but the coupling is less obvious when there is no aurora.Therefore,it is very important to detect the thermospheric neutral wind,especially during auroral substorms in the polar region.The thermospheric wind was analysed,which was based on the joint observation project of Wuhan University Laser Communication Laboratory and Nagoya University,the observations were made by an all-sky Fabry-Perot Interferometer(FPI)at the Chinese Yellow River Station(11.92 °E,78.92 °N)and a scanning FPI at Tromso Station(19.2 oE,69.6 oN)during the auroral substorms on January 12,November 25,and December 6,2016.The data was used to compare and analyze thermospheric wind retrieved by FPI in the two places.It was found that in the presence of aurora,the thermospheric wind might be enhanced,as well as suppressed.Considering geomagnetic data of the International Monitor for Auroral geomagnetic Effect(IMAGE),the fitting ion drift given by the Super Dual Auroral Radar Network(SuperDARN)and incoherent scattering radar association(EISCAT),wind enhancement or suppression was closely related to ion drift during substorm.Furthermore,the neutral wind was enhanced when they were in the same direction,and it was suppressed when they were in the opposite direction.Ion drag was believed to be a major role in the wind variation of during the three auroral substorms.By comparing auroral morphology of all sky imager with wind variation,it was found that auroral motion might be related to ion drift and in the continuous auroral motion,the neutral wind component,which was perpendicular to auroral arc,affected the overall motion of the arc,while the tangential component changed the shape of aurora,and there was obvious wind disturbance in the dark or relatively weak area of aurora patch.The uneven distribution of aurora led to wind oscillation,which was not seen in the previous analyses of allsky FPI data at Yellow River station,which provided a new perspective for studying the mechanism and variation of thermospheric wind during auroral substorms.