本文針對福衛三號2006.07~2007.02電離層電子濃度資料設計一套品質篩選( Quality Control )的流程：首先，利用電子濃度對高度的斜率正負變換，重新定義原始資料中的F2 層的峰值高度( Layer Peak-height )與最大電子密度( Peak-density )，另外，定義兩個參數，其一是420 km與490 km處的電子濃度對高度的斜率( Slope )，另一是140 km以上電子濃度的擾動量( Mean Deviation )，利用物理與統計特性替這兩項參數設定了門檻值：-9 < Slope < -0.02與M.D.< 3，在門檻值之內屬於品質較優的資料；經過F2 Layer Peak-height重新定義與Slope、M.D.的條件篩選後，將其資料與IRI 模式(Model)模擬值、電離層觀測儀( Ionosonde )觀測值作一比較，證實經篩選後的資料遠優於未經篩選的資料；再與IRI模擬值作一差異值的分布比較，差異值多發生在赤道正負20度的區域，且都是IRI模擬值偏高。分別再針對前述定義的Slope與M.D.做日變化與季節變化，可以觀察到Slope的變化情形與F2 Layer Peak-density呈負相關，而M.D.有顯著變化的區域則與電漿泡發生的分布情形類似。

We develop a Quality Control algorithm in this study to screen out bad FORMOSAT-3/COSMIC-retrieved electron density profile collected during the period from July 2006 to February 2007. First of all, we redefine the F2 Layer Peak-height and F2 Layer Peak-density of the raw data. Second, we define two new parameters for the use of the data quality control: one is Slope which is the vertical gradient of the electron density for the height range 420-490 km, the other one is Mean Deviation (M.D.) which is the summation of the relative deviation of the raw electron density from the background electron density profile that is obtained by doing 9-point running average on the original electron density profile above 140 km. According to the statistics analysis, we select thresholds for these two parameters: -9 < Slope < -0.02 and M.D. < 3, namely, the electron density profile with the slope and M.D. are, respectively, within their thresholds is accepted for further analysis. We compare the data between COSMIC measurement and IRI Model and find that the threshold that we define are pertinent and acceptable. With good quality data, we compare COSMIC-measured electron density with IRI model data. We find that the differences in the two are primarily distributed along the geomagnetic equator. We also compare the seasonal and diurnal variations of Slope and M.D.. The result shows that Slope is negatively correlated with F2 Layer Peak-density and the variation of M.D. is distributed in the region where the plasma bubbles are frequently occurred.

1. Born, M., and E. Wolf, Principles of Optics, Cambridge university, New York, 1999.
2. Fjeldbo, G., A. J. Kliore, and V. L. Eshleman, The neutral atmosphere
of Venus as studies with the Mariner V radio occultation experiment,
Astron. J., 76, 123-140, 1971.
3. Kenneth Davis, Ionospheric Radio, Peter Peregrinus Ltd, p70-73,
p96,p159, p172, London, 1990.
4. Kursinski, E. R., G. A. Hajj, J. T. Schofield, R. P. Linfield, and K.
R.Hardy, Obeserving Earth’s atmosphere with radio occultation
measurements using the Global Position System, J. Geophys. Res.,
102, 23429-23465, 1997.
5. M. C. Kelley, The Earth’s ionosphere, Academic Press, p5, 1989.
6. Rius A., G. Ruffini, and A. Romeo, Analysis of ionospheric electron
density distribution from GPS/MET occultations, IEEE Trans.
Geosci. Remote Sensing, Vol. 36, No. 2, 383-394, 1998.
7. Tascione , F. T. , Introduction to the Pace Environment , Krieger
Publication Company , Malabar , Florida ,1944
8. Tricomi, F. G., Integral Equations, Dover, Mineola, N. Y., 1957.
9. William S. Schreiner, Sergey V. Sokolovskiy, Christian Rocken, and
　Douglas C. Hunt, Analysis and validation of GPS/MET radio　
　occultation data in the ionosphere, Radio Science, Volume 34, Number
4, Pages 949-966, July-August 1999
10.黃清勇、朱延祥，FORMOSAT-3&COSMIC科學研究發展簡介，
「大氣科學」，32，293-328,2004
11.蔡和芳，「全球定位系統觀測電離層赤道異常之研究」，國立中
央大學太空科學研究所，博士論文，1999
12.何美蓉，「利用福衛一號研究頂部電離層之電漿不規則體」，國立
中央大學太空科學研究所，博士論文，2006
13.陳襄，「GPS/MET及中壢DSP電離層觀測比較」，碩士論文，國
立中央大學太空科學研究所, 2000
14.安守中，GPS全球衛星定位系統入門，全華科技圖書股份有限公司，
2002