高层大气测风用地基F-P干涉仪的数值模拟

Simulation of ground-based Fabry-Perot interferometer for the measurement of upper atmospheric winds

热层大气风场、温度场对热层-电离层耦合研究、热层环流特性研究以及太阳活动和地磁活动研究等有着重要意义,同时其也是航天器飞行环境预报的重要物理基础.目前,由于热层所处位置较高,大气非常稀薄,风场探测难度较大,因此针对热层大气风场的探测手段非常少.Fabry-Perot(FP)光学干涉仪可通过观测气辉来进行风场探测,其对成像系统像质要求不高,在设计中无需过分追求像质,已经成为热层风场测量的重要工具.由于风场观测气辉的辐射强度非常微弱,因此必须进行FP干涉仪测量系统优化,获得相对较强的辐射强度,以提高风场测量精度.但目前,对FP干涉仪系统优化方面的研究较少,且在测风误差评价方面的工作也不充实.本文通过热层测风用固定间距标准具地基FP干涉仪数值模型的建立,解决FP干涉仪设计过程中各参量的优化问题,并提出一种新的测风误差估算方法.数值模型结果分析表明,在目前探测器观测技术水平下,采用全部干涉环参与计算并结合像元合并技术进行风速反演可最大限度地提高测量精度.此外,由于气辉辐射强度是影响热层大气风场测量精度的重要因素,因此在仪器测风精度性能评价时需确定观测对象强度,即气辉的辐射强度.

Thermospheric winds and temperatures are very important for the studies of the coupling of thermosphere and ionosphere,thermospheric circulation and the effects of geomagnetic and solar activities.And they are also physical fundaments of satellites environmental forecast.To date,however,there have been few instruments for the upper atmospheric wind measurements because of high altitude and rarefied air of thermosphere.Because of the low image quality requirement of imaging system,Fabry-Perot（FP） interferometer has been widely used for thermospheric wind measurements.Considering the low intensity of the airglow from observation object,it is critical to optimize the FP interferometer instrument system for collecting the stronger airglow intensity and getting higher wind retrieval precision.However,few studies of optimizing FP interferometer and detailed wind retrieval error evaluation were carried out.In this paper,by establishing the numerical simulation model of the fixed etalon spacing ground-based FP,parameters optimization of FP interferometer was made and a new method for wind retrieval error was proposed.The results demonstrated that,at current level of wind measurements,wind retrieval using all usable interference fringes can get higher wind retrieval precision with pixels bin.Furthermore,owing to great effects of airglow intensity on the wind measurements,it is essential to give the measured airglow intensity when the performance of FP instrument measurement is evaluated.