利用低傾角衛星-福爾摩沙衛星一號以及高傾角衛星-DEMETER 與福爾摩沙衛星五號，觀察磁赤道附近（±15°磁緯度）電離層離子濃度不規則體，研究其全球分佈之月變化、經度變化、地磁擾動變化、太陽活動變化，並探討衛星傾角對不規則體觀測之影響。使用希爾伯特黃轉換之瞬時特性，計算離子濃度差分之瞬時總振福，並比對其與不規則體發生率之異同。福衛一號與 DEMETER 不規則體發生率分佈顯著不同。在南美洲區域，DEMETER 幾乎每個月份皆觀測到不規則體之發生，尤其是五月到八月十分盛行。福衛一號不規則體的發生會隨著月份偏移，一月由南美洲東岸出發，七月抵達非洲西岸，並於十二月返還南美洲東岸。福衛五號與福衛一號不規則體發生率於南美洲東岸至非洲西岸經度有些相似，而於其他經度則大相逕庭。反之，三顆衛星不規則體瞬時總振福之經度分佈均相似。除了 DEMETER 五月到八月南美洲地區不規則體發生率之外，整體而言，三衛星之發生率和瞬時總振福皆與太陽活動呈正比。福衛一號不規則體發生率和瞬時總振福在磁擾動期間有抑制效應，而 DEMETER 和福衛五號則相反。推測是由於太陽極小期間，磁擾動引發催生效應。福衛一號、DEMETER 和福衛五號觀測值之詳細比較表明，2006-2010 年 5 月至 8 月南美洲區域發生率差異是由極低之環境電漿密度造成，並非衛星傾角。

This thesis investigates the variations of equatorial ionospheric irregularity by means of ROCSAT-1, DEMETER, and FORMOSAT-5 during 1999-2004, 2006-2010, and 2018-2019, respectively. The occurrence probability and the instantaneous total amplitude derived from Hilbert-Huang transform are used to survey seasonal, longitudinal, magnetic, solar activity variations in the equatorial/low-latitude ionospheric irregularities. The probability and the amplitude of ROCSAT-1 display that the region of the prominent occurrence rate varies month by-month, which shifts from the South American sector in January to the African sector in July and returns to the South American sector by December. Meanwhile, low occurrence rate is
more or less evenly distributed in other longitudes for the two equinox seasons. The probability of DEMETER is quite different from that of ROCSAT-1, especially during May July in South American sector. On the other hand, the occurrence probability of FOMOSAT-5 is somewhat similar to that of ROCSAT-1 in South American－African sector, and however it is very different in other longitude regions. By contrast, the instantaneous total amplitude of the three satellites display nearly identical longitudinal variations in South American－African sector. In various longitudes and months, the probability and the amplitude of the three satellites within ±15° magnetic latitudes show the owl face feature. Generally, the occurrence probability and the instantaneous total amplitude are proportional to the solar activity, except the discrepancy region of probability of DEMETER in May to August. The magnetic activity might act a seeding effect on irregularities during the low solar activity periods. The detailed comparisons in observations between ROCSAT-1 and DEMETER/FORMOSAT-5 show that the discrepancy in the occurrence probability over the South American sector during May-August in 2006-2010 results from the extremely low ambient ion density.

Aarons, J. (1977), Equatorial scintillations: A review,
IEEE Trans. Antenna Propagat., 25, 729.
Booker, H. G., and H. W. Wells (1938), Sowltering of radio
waves by the F region ionosphere, J. Geophys. Res., 43,
249-256.
Chao, C. K., S. Y. Su, H. C. Yeh (2004), Ion temperature
crests and troughs in the morning sector of the low-
latitude and midlatitude topside ionosphere. J. Geophys.
Res. 109, A11303.http://dx.doi.org/10.1029/2003JA010360.
Chao, C. K., S. Y. Su, H. C. Yeh (2006), Ion temperature
variation observed by ROCSAT-1 satellite in the
afternoon sector and its comparison with IRI-2001 model.
Adv. Space Res. 37, 879–884.
http://dx.doi.org/10.1016/j.asr.2005.06.071.
Cussac, T., M. A. Clair, P. Ultré‐Guerard, F. Buisson, G.
Lassalle‐Balier, M. Ledu, C. Elisabelar,
X. Passot, and N. Rey (2006), The DEMETER microsatellite
and ground segment, Planet. Space Sci., 54(5), 413–427.
Davies K. (1990), Ionospheric Radio, Peter Peregrinus,
London, UK.
Farley, D. T., B. B. Balsley, R. F. Woodman, and J. P.
McClure (1970), Equatorial spread F: Impliowlions of VHF
radar observations, J. Geophys. Res., 75, 7199-7216.
Gentile, L. C., W. J. Burke, and F. J. Rich (2006), A
global climatology for equatorial plasma
bubbles in the topside ionosphere, Ann. Geophys., 24,
163–172, doi:10.5194/angeo-24-163 2006.
Feng, D. J., and C. H. Liu (1983), A morphological study
of gigahertz equatorial scintillations in the Asian
region, Radio Sci., 18, 241.
Fejer, B. (1991), Low latitude electrodynamic plasma
drift: A review, J. Atmos. Terr. Phys., 53, 677.58
Fejer, B., and L. Scherliess (1997), Empirical models of
storm time equatorial zonal electric fields, J. Geophys.
Res., 102, 24,047.
Fejer, B. G., J. W. Jensen, and S. Y. Su (2008), Quiet
time equatorial F region vertical plasma drift model
derived from ROCSAT-1 observations, J. Geophys. Res.,
113, A05304, doi:10.1029/2007JA012801.
Huang, C. S., O. de La Beaujardiere, P. A. Roddy, D. E. Hunton, J. Y. Liu, and S. P. Chen (2014), Occurrence
probability and amplitude of equatorial ionospheric
irregularities associated with plasma bubbles during low
and moderate solar activities (2008–2012), J. Geophys.
Res. Space Physics, 119, 1186–1199,
doi:10.1002/2013JA019212.
Huang, N. E. and Z. Wu. (2008), A review on Hilbert-Huang
transform: Method and its applications to geophysical
studies. Reviews of Geophysics, 46: RG2006.
Huang, N. E., Z. Wu, S. R. Long, K. C. Arnold, X. Chen,
and K. Blank (2009), On instantaneous frequency.
Advances in Adaptive Data Analysis, 01(02): 177–229.
Huang, N. E., Z. Shen, S. R. Long, M. C. Wu, H. H. Shih,
Q. Zheng, N. C. Yen, C. C. Tung, and H. H. Liu (1998),
The empirical mode decomposition and the Hilbert
spectrum for nonlinear and non-stationary time series
analysis. Proceedings of the Royal Society of London
Series A, 454:903–998.
Kelley, M. C. (1989), The Earth’s Ionosphere: Plasma
Physics and Electrodynamics, Academic Press, San Diego.
Kelley MC (2009), The Earth’s ionosphere: electrodynamics
and plasma physics, 2nd edn. Elsevier, New York
Kil, H., L. J. Paxton, and S.-J. Oh (2009), Global bubble
distribution seen from ROCSAT-1 and its association with
the evening prereversal enhancement, J. Geophys. Res.,
114, A06307, doi:10.1029/2008JA013672. 59
Liu, J. Y., Y. Y. Sun, C. K. Chao, S. P. Chen, and M.
Parrot (2017), An observing system simulation experiment
for FORMOSAT-5/AIP probing topside ionospheric plasma
irregularities by using DEMETER/IAP. Terr. Atmos. Ocean.
Sci., 28, 111-116, doi: 10.3319/TAO.2016.08.18.01(EOF5)
McClure, J. P., S. Singh, D. K. Bamgboye, F. S. Johnson, H. Kil (1998), Occurrence of equatorial F region
irregularities: evidence for tropospheric seeding. J.
Geophys. Res. 103 (A12), 29119–29135.
http://dx.doi.org/10.1029/98JA02749.
Mendillo, M., B. Lin, J. Aarons (2000), The appliowlion of
GPS observations to equatorial aeronomy, Radio Sci.,
35,885-904.
Ossakow SL (1981), Spread F theories—a review. J Atmos
Solar Terr Phys 43:437–452
Ott E (1978), Theory of Rayleigh-Taylor bubbles in the
equatorial ionosphere. J Geophys Res 83(A5):2066–2070.
doi:10.1029/JA083iA05p02066
Retterer, J. M. (2010), Forecasting low-latitude radio
scintillation with 3-D ionospheric plume models: 1.
Plume model. J. Geophys. Res., 115, A03306,
doi:10.1029/2008JA013839.
Rino, C. L., R. T. Tsunoda R. T., J. Petriceks, R. C.
Livingston, M. C. Kelley, and K. D. Baker, (1981).
Simultaneous rocket-borne beacon and in situ
measurements of equatorial spread F—intermediate
wavelength results. J. Geophys. Res. 86, 2411.
Sahai, Y., P. R. Fagundes, J. A. Bittencourt (1999), Solar
cycle effects on large scale equatorial F-region plasma
depletions. Adv. Space Res. 24, 1477-1480
Sobral, J.H.A., M. A. Abdu, H. Takahashi, M. J. Taylor, E.
R. De Paula, C. J. Zamlutti, M. G. De Aquino, G. L.
Borba (2002), Ionospheric plasma bubble climatology
over Brazil based on 22 years (1977–1998) of 630 nm
airglow observations. J. Atmos. Solar Terr. Phys. 64,
1517– 1524, 2002. 60
Su, S. Y., C. H. Liu, H. H. Ho, and C. K. Chao (2006),.
Distribution characteristics of topside ionospheric
density irregularities: Equatorial versus midlatitude
regions. J. Geophys. Res., 111, A06305, doi:
10.1029/2005JA011330.
Su, S.Y., C. K. Chao, C. H. Liu (2008), On
monthly/seasonal/longitudinal variations of equatorial
irregularity occurrences and their relationship with the
postsunset vertical drift velocities. J. Geophys. Res.
113, A05307. http://dx.doi.org/10.1029/ 2007JA012809.
Su, S. Y., M. Q. Chen, C. K. Chao, and C. H. Liu (2010),
Global, seasonal, and local time variations of ion
density structure at the low-latitude ionosphere and
their relationship to the postsunset equatorial
irregularity occurrences. J. Geophys. Res., 115, A02309,
doi:10.1029/2009JA014339.
Sultan PJ (1996), Linear theory and modeling of the
Rayleigh-Taylor instability leading to the occurrence of
equatorial spread F. J Geophys Res 101(A12):26875–26891.
doi:10.1029/96JA00682
Sun, Y. Y., J. Y. Liu, C. K. Chao, and C. H. Chen (2015),
Intensity of low-latitude nighttime F region ionospheric
density irregularities observed by ROCSAT and ground-
based GPS receivers in solar maximum. J. Atmos. Sol.
Terr. Phys., 123, 92-101,
doi:10.1016/j.jastp.2014.12.013.
Tsunoda, R. T., R. C. Livingston, J. P. McClure, and W. B.
Hanson (1982), Equatorial plasma bubbles: Vertically
elongated wedges from the bottomside F layer. J.
Geophys. Res. 87, 9171.
Tulasi Ram, S., S. Y. Su, C. H. Liu, B. W. Reinisch and
L.-A. McKinnell (2009), Topside ionospheric effective
scale heights (HT) derived from ROCSAT-1 and ground-
based Ionosonde observations at equatorial and
midlatitude stations, J. Geophys. Res., 114, A10309,
doi:10.1029/ 2009JA014485.
Wu, Z. and N. E. Huang (2009), Ensemble empirical mode
decomposition: a noise-assisted data analysis method.
Advances in Adaptive Data Analysis, 1(1):1–41. 61
Yeh, H. C., S. Y. Su, Y. C. Yeh, J. M. Wu, R. A. Heelis
and B. J. Holt (1999), Scientific mission of the IPEI
payload onboard ROCSAT-1, Terr. Atmos. Oceanic Sci.,
suppl., 19–42.
Yokoyama, T., H. Shinagawa, and H. Jin (2014), Nonlinear
growth, bifurcation, and pinching of equatorial plasma
bubble simulated by three-dimensional high-resolution
bubble model. J. Geophys. Res., 119, 10474-10482, doi:
10.1002/2014JA020708.