利用福爾摩沙衛星三號資料分析頂部電離層與F層特性

Analyses of topside ionosphere and F region characteristics by FORMOSAT-3/COSMIC ionospheric data

夏希璞(Hsi-Pu Hsia)

指導教授 ： 朱延祥

國立中央大學/地球科學學院/太空科學研究所/碩士(2008年)

摘要

福爾摩沙衛星三號(COSMIC)利用電波掩星法(Radio Occultation) 反演電離層電子濃度剖面，涵蓋全球的觀測範圍使我們可以跳脫以往局部區域的觀測限制。在過去，頂部電離層(高度高於電子濃度hmF2以上)觀測相較之下遠少於底部電離層，因此頂部電離層區域的資訊仍然相當缺乏。例如，頂部電離層的標尺高(topside scale height)、垂直擴散速度(vertical diffusion velocity)以及頂部電離層全電子含量(topside TEC)。本論文將比較IRI模型與COSMIC在F2層峰值-NmF2、F2層峰值高度hmF2、頂部電離層的標尺高(topside scale height)與頂部電離層全電子含量(topside TEC)在全球分佈的變化、季節變化與日變化等特性。發現IRI模型與COSMIC觀測的電子濃度剖面在低緯度的夜間有很大的差異，尤其是在頂部電離層的區域。而從2006年9月到2008年2月累積18個月COSMIC的觀測資料，可以觀察電子濃度平均的季節變化，以及太陽活動的影響。

關鍵字

福衛三號 ； 電離層 ； 頂部電離層 ； 標尺高 ； 全電子含量

並列摘要

With the globally coveraged observations of electron density profile retrieved from FORMOSAT-3/COSMIC radio occultation measurements, we are able to avoid the limitation of past measurements. In the previous investigations, most measurements of ionosphere focus on bottom side ionosphere, therefore the information on properties of topside ionosphere are not well-documented, including scale height, vertical diffusion velocity, total electron content(TEC), and so on. This dissertation compares ionospheric parameters, such as NmF2, hmF2, topside scale height and topside TEC, between IRI model and COSMIC data globally. Their seasonal variation and daily variation are also studied. We find that there is significant difference between COSMIC measurement and IRI model for nighttime low latitude, especially in the topside ionosphere. With 18 months COSMIC data from 200609 to 200802, we also observe the seasonal variation of peak electron density and its relation to the solar activity. The result shows a positive correlation between them.

並列關鍵字

FORMOSAT3 ； ionosphere ； TEC ； scale height ； topside ionosphere

參考文獻

[1] Abdu, M. A., J. H. Sobral, P. Richard, Marta. M. degonzalez, Y. N. Huang, B. M. Reddy, K. Cheng, E. P. Szuszcewicz, andI. S. Batista. Zonal/meridional wind and disturbance dynamo electric field control of the low-latitude ionosphere based on SUNDIAL/ATLAS 1Campaign, J. Geophys. Res., 101, 26729-26740, 1996.

[2] Aggson, T. L., F. A. Herrero, J. A. Johnson, R. F. Pfaff, H. Laakso, N. C. Maynard and J. J. Moses, Satellite observation of zonal electric field near sunrise in the equatorial ionosphere, J. Atmos. Terr. Phys., 57, 19-24, 1995.

[3] Behnke, R. A., M. Kelly, G. Gonzales, M. and Larsen, Dyanmic of the Arecibo ionosphere, A case study approach, J. Geophys. Res., 90, 4448-4452, 1985.

[5] Chapman. S., The electric conductivity of the ionosphere: A review. Nuovo Cimento 5, Suppl., 1385-1412.

[6] Farley, D. T., E. Bonelli, B. G. Fejer, and M. F. Larsen, The prereversal enhancement of the zonal electric field in the equatorial ionosphere , J. Geophys. Res. 91, 13723-13728, 1986.