| 摘要: | 電漿不規則體普遍發生於電離層中，包含E 層及F 層。而在磁赤道及高緯地區，對於不規則體的觀測和理論發展的瞭解更優於在中低緯度地區。在赤道電離層E 層中造成不穩定電漿波的機制主要為雙流性及梯度漂移不穩定。一般在中低緯度E 層中的不規則體大部份源自於梯度漂移不穩定，雖然極為有限的觀測結果源自於雙流性不穩定。由於有限的磁傾角存在於中低緯度地區，用於磁赤道地區的不穩定機制並不能簡單的使用於此地區。因而在這十幾年來，有各種機制被提出來解釋所觀測的資料，例如，重力波的調變、中性風切的發電效應、局部理論之中性風效應，以及非局部理論之梯度漂移不穩定，等等。其中的中性風切發電效應會導致不規則呈現出特別的方位排列。本計畫的要點之一就是可以檢視此機制存在的可能性。執行的方式就是利用30M 及52M 雷達來作聯合觀測。本計畫之重要性在於透過觀測的資料判斷出在中低緯度E 層中合理的引發機制。另外，本計畫的一個重要目的是借由即將更新的發射機來觀測中低緯度F 層夜間電埸隨時間的分佈並與電離層模式，例如TIEGCM，作比對。這個重要的觀測資料至今在中壢上空從未建立，希望能透過此計畫的執行來完成。 Plasma irregularities are ubiquitously existed in the ionosphere, including E region and F region. The understanding of the observations and theoretical development at the geomagnetic equator and high latitudes are better than that at mid-, low-latitudes. At geomagnetic equator, the irregularities in the E region are mainly produced by two-stream instability and gradient drift instability. At mid-, low-latitudes, the E region irregularities are mostly resulted from gradient drift, although very limited observations are related to two-stream instability. The mechanisms developed for unstable plasma waves at the geomagnetic equator cannot be easily quoted at the mid-, low- latitudes, because of the existence of the finite dip angle. Various mechanisms, therefore, are provided to explain the observations during the last decade, for example, the gravity wave modulation、the neutral wind shear dynamo、neutral wind effect of the local theory, and the non- local theory for the gradient drift instability, and so on. Specially, the irregularities resulted from the neutral wind shear dynamo would be aligned in a special orientation. An important capability of this project is to investigate the possibility of this mechanism through the campaign observations of 30M and 52M radar. The importance of this project is to identify the reasonable mechanism associated with the irregularities in the E region at mid-, low-latitudes from the observational database. Another purpose is to quantify the nighttime variations of the F region electric fields using the updated transmitter in the coming two years, and to compare with the global ionosphere model, for example, TIEGCM. It is also highly expected that the important database could be satisfactorily build up with the execution of this project. 研究期間：9608 ~ 9707 |
