電離層參數判讀演算法與電離圖實高分析

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Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/76719

Title:	電離層參數判讀演算法與電離圖實高分析
Authors:	柯凱鈞;Ke, Kai-Jun
Contributors:	太空科學研究所
Keywords:	電離層參數;實高分析;ionospheric parameter;true height analysis
Date:	2018-07-10
Issue Date:	2018-08-31 11:34:21 (UTC+8)
Publisher:	國立中央大學
Abstract:	為了從電離層探測儀觀測到的電離圖中找出電離層參數與其對應的電子密度分布，本文將提出一套新的自動判讀演算法。在電離圖資料處理部份，將背景雜訊移除，並利用影像處理方式擷取正、異常波訊號軌跡以及得到電離層參數。本文將使用類拋物線分層模型(Quasi-Parabolic Segment, QPS)作為電子密度分布反演的理論，其初始參數將由國際電離層參考模型(International Reference Ionosphere, IRI)的電離層參數以及電離圖資料判讀的參數所提供。以初始參數作為參考並進行參數調整設定，即可得到上千組電離層參數，利用QPS model模擬出的電子密度分布進行實高分析，得到正常波訊號的合成軌跡。利用正常波合成軌跡與實際電離圖正常波軌跡的相互比較，找出所有電離層參數組中相關係數最大值和均方根誤差(RMSE)最小值的參數組當作最後的電離圖判讀結果。本文使用甘肅地區的原始電離圖資料進行自動判讀演算法分析，其判讀電離層參數之結果將對精準度和誤差部分進行討論。;In order to precisely estimate ionospheric parameters with corresponding electron density profiles form the ionogram observed by this ionosonde system, a new algorithm is developed to scale the ionogram traces. We first remove background noise from the ionogram. We use an image processing technique to identify the observed O- and X-wave traces, then obtain preliminary ionospheric parameters based on separated O- and X-wave traces. In this study, the quasi-parabolic segment (QPS) model is exploited to obtain the electron density profile, and the IRI model is also used to generate the initial inputs. According to the scaled ionospheric parameters from the O-wave traces combined with the inputs of the IRI model, it is easy to retrieve the QPS model-based electron density profiles. From the retrieved electron density profiles, the corresponding O-wave traces can be simulated and compared with the observed one. The root mean square errors (RMSEs) between observed and simulated O-wave traces are validated and the ionospheric parameters of the constructed trace with the minimum RMSE value and the best correlation-coefficient are then selected as the final result of the ionogram scaling. The accuracy and precision of the estimated ionospheric parameters by using the proposed algorithm are also analyzed and discussed.
Appears in Collections:	[Graduate Institute of Space Science] Department of Earth Sciences

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