1997 Fiscal Year Final Research Report Summary
A study on the auroral tomography analysis
| Project/Area Number |
07640588
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Space and upper atmospheric physics
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| Research Institution | National Institute of Polar Research (1997)
Kyoto University (1995-1996) |
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Principal Investigator |
ASO Takehiko National Institute of Polar Research, Arctic Environment Research Center, Professor, 北極圏環境研究センター, 教授 (10026255)
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| Co-Investigator(Kenkyū-buntansha) |
HASHIMOTO Takeshi Shizuoka University, Faculty of Engineering, Assistant Professor, 工学部, 助教授 (60228418)
EJIRI Masaki National Institute of Polar Research, Data Archiving Division, Professor, 資料系, 教授 (30013692)
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| Project Period (FY) |
1995 – 1997
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| Keywords | Aurora / Tomography / Monochromatic images / Inversion / MART / SIRT / ALIS / EISCAT |
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| Research Abstract |
Auroral tomography is an inverse problem to reconstruct 3-D luminous structure of aurora from multi-point CCD images. We had been studying auroral stereopsis by the functon fitting and algebraic MART methods before the first collaborative observations with ALIS optical observing network of the Swedish Institute of Space Physics came true and brought about 5-point monochromatic images in March, 1995. Tomographic inversion codes for 3-D reconstruction have since been developed, being upgraded from stereographic program, together with the computer user interface for manipulating multiple images. The algebraic techniques as the MART and SIRT were adapted with uniform field-aligned characteristic in its proximity assumed as a constraint to sometimes underdetermined auroral tomography. Analytic methods based on the Radon transform were also studied. In December 1995,6-point observation was carried out, and various types of aurora images obtained so far were analyzed by the modified MART and
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SIRT methods. Studies on the uniqueness of reconstruction.legitimacy of camera imaging models and sub-voxel sophistication were also worked out in parallel with the analysis. Reconstructed structure contributes to quantitative study in view of elementary formation process and dynamical behavior of auroras. Further numerical tests for various inversion algorithms were also continued. Fully remotely-controlled ALIS operation in early 1977 aimed at conjunctive studies of aurora with FAST satellite and EISCAT radar. Comprehensive analyzes of these data are still underway. Tomographic analysis has been undertaken with the result of further indications on the altitude profiles at different wavelength, stopping height distribution along aurora and structures of vortex or multiple arcs. Restoration of absolute value of auroral emission rate by the radiometric calibration of camera characteristics using an integration sphere and computer visualization of reconstructed results have also been investigated. Less
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