电离层LBH日辉辐射大视场计算方法

A method to calculate the ionospheric LBH dayglow emissions for the large field of view

LBH日辉辐射是由光电子与氮气分子碰撞激发而产生的,是电离层在远紫外辐射波段中最强的分子辐射信号.从空间对电离层LBH日辉辐射进行成像观测为高层大气状态的监测提供了一种强有力的方法.本文分析了LBH辐射的谱带特征,采用电子碰撞直接激发理论,使用球几何大气模型,针对大视场观测模式,给出了一种改进的LBH日辉柱辐射率计算方法RAURIC.RAURIC针对AURIC辐射算法的局限性主要有两点改进:一是增加了观测方位角;二是考虑了沿观测视线LOS方向上太阳天顶角的变化.我们使用RAURIC计算了140～180nm波段的LBH日辉辐射,并与AURIC进行了比较,结果表明:在天底方向上,二者具有非常好的一致性;在其他观测方向上,尤其在大视场观测模式下,则需要使用RAURIC进行计算.本文工作为电离层LBH日辉图像模拟技术与数据反演技术的研制奠定了基础.

LBH dayglow emissions in the ionosphere,produced by the photoelectrons impact on the nitrogen molecules,are the most prominent molecular signals in the far ultraviolet emission range.Imaging the LBH dayglow emissions from the space can be a powerful method to monitor the state of the upper atmosphere.We analyze the spectral characteristics of the LBH emissions according to the direct excitation theory and the spherical geometry,and give a revised method to calculate the column emission rates of the LBH dayglow emissions for the large field of view.The RAURIC mainly improves two limitations of AURIC;one is the definition of the observation zenith angle,and the other is treating the Solar Zenith Angle as a variable along the LOS direction.With this method,we calculate the column emission rates of the LBH bands in therange of 140～180nm.Comparison of the results of RAURIC with AURIC shows that they have great agreement in nadir,while in other lines of sight we should use RAURIC,especially for the large field of view.Thus,this work builds a solid basis for simulating the image of ionospheric LBH dayglow emissions and the data inversion technique.