摘要 中華衛星一號（福衛一號）以傾角35度的圓形軌道繞行，在某些經度上它的軌道可涵蓋45度磁緯度。值磁暴發生期間中高緯度現象電離層會往低緯度方向延伸，所以我們有機會觀測到中緯度現象。在2003 10/29至 10/31 所發生的巨型磁暴期間置於華衛一號電離層的電漿電動儀（IPEI）觀測到快速電漿流現象。這些受極向電場驅動的西向電漿流常被歸類為副極光區極化電漿流（Subauroral Polarization Stream或簡稱SAPS）。以往這種現象的討論都局限在中高緯度以上的改變以及較大尺度的結構變化，而本篇論文討論在巨型磁暴中SAPS的邊界如何往中低緯度延伸及伴隨這些改變的中尺度（500 m ~ 60 km）擾動波。我們專注在這磁暴期間的三個SAPS時段，且比較三個不同時段 的差異。這所選取的三個時段中，平均西向電漿流的速率為500 m/s ~ 600 m/s，而最快到達1200 m/s，環繞這特高速率的區域也特別定義為副極光區離子流（Subauroral Ion Drift或簡稱SAID）。SAPS的低緯度邊界最低達磁緯度26度，而他們的地方時分佈可以延伸至白天下午的15:30。另外除了極向電場，我們也觀測到強烈的東向電場。最後我們也對此次事件作細部的波譜分析及波偏極性分析，發現在SAID發生的時間（或位置）有左旋極化的中尺度波存在（波長約3.16 km）。 Abstract The ROCSAT-1 satellite was launched into a circular orbit with inclination of 35 degrees. Its orbits can cover magnetic latitudes (Mlat) up to 45 degrees in some longitude sectors. During storm time the mid-latitude and high-latitude phenomena can expand equatorward, so it is possible for us to observe mid-latitude phenomena at ROCSAT-1 orbits. During the great magnetic storm on 29 – 31 October 2003 (Halloween storm), the onboard Ionospheric Plasma and Electrodynamics Instrument (IPEI) observed unusually rapid plasma drifts in the sub-auroal latitudes. These westward drifts were driven by polarward electric fields. We characterize these westward flows as the Subauroral Polarization Stream (SAPS). In this thesis we investigate the equatorward extent of the SAPS events and discuss the structures of the intermediate scale (500 m ~ 60 km) wave phenomena. In particular, we focus on three SAPS events during the expansion phase of this storm period. From these events we find that the average westward velocity is 600 m/s ~ 800 m/s and that the maximum velocity exceeds 1200 m/s. Surrounding this velocity peak is a narrow latitude region, which is named “Subauroral Ion Drift (SAID)”. The lowest SAPS equatorward boundary extended to 26o Mlat, and local time extended toward mid-afternoon (15:30 LT). In addition to polarward electric field, we also observed eastward electric fields. Furthermore, we analyze the spectral and polarization characteristics of the wave events. At the location nearby the SAID event, we observed the narrow-band waves, which are left-hand polarized with wavelengths around 3.16 km.
