扫描式F-P干涉仪在MERINO观测中的热层风结果与分析

MERINO是沿120°E/60°W子午圈的全球联网观测项目,热层中性风是其中一个十分重要的观测参数.本文介绍了武汉大学扫描式F-P干涉仪(SFPI)及其在MERINO第一轮观测中的结果,并与同站点的流星雷达在98 km高度上的测风数据进行了验证,分析表明两台设备的吻合性很好,SFPI风速测量的误差分别为8 m·s^-1(557.7 nm)和7.8 m·s^-1 (630.0 nm).本文对地基扫描式FPI的误差做了详细分析,结果表明在FPI仪器设计之初,就需要考虑标准具通光孔径D和成像物镜焦距f的合理组合,在目前CCD和标准具规格的限制下,增加f会提高测风精度,但会牺牲通光量,可通过设置CCD为Binning读出模式来提高灵敏度.在FPI进行风场观测时,要对设备工作的环境温度进行控制,特别是控制标准具的温度漂移.FPI的测风精度可以理论推导,但实际测风误差还与反演算法、元器件的加工和安装精度有关,国际通用的误差评价方法是用统计偏差来表示.

Thermospheric wind observation by a scanning Fabry-Perot interferometer during MERINO campaign

MERINO is a network for space weather monitoring along the meridian circle (120°E/60°W),and the thermospheric neutral wind is one of the important parameters to be measured. This paper introduces the scanning F-P interferometer (SFPI) developed by Wuhan University, and shows its winds observation results in the first round of the MERINO campaign. It is found that the results of SFPI are in good agreement with those of meteor radar in the same site, with the wind speed errors <8 m·s^-1 at 557.7 nm and <7.8 m·s^-1 at 630.0 nm.The paper gives a detailed analysis on the wind retrieval error. The results show that the etalon clear aperture D and the imaging lens focal length f should be carefully selected in the beginning of FPI instrument design. Under the limit of current CCD and etalon, the increase of f would improve the wind retrieval precision but reduce the amount of light, and consequently the CCD should operate in the Binning readout mode to improve the sensitivity. The environment temperature, and especially the etalon space drift should be controlled to perform the wind observations. The precision of wind measurement can be calculated theoretically, but the actual error is influenced by the fabrication and installation of components and wind derivation method. In general, the statistical analysis is required to evaluate the error.