| Project/Area Number |
06554017
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 試験 |
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| Research Field |
Meteorology/Physical oceanography/Hydrology
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
TSUDA Toshitaka Kyoto University, Radio Atmospheric Science Cneter, Professor, 超高層電波研究センター, 教授 (30115886)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAMURA Takuji Kyoto University, Radio Atmospheric Science Cneter, Research Associates., 超高層電波研究センター, 助手 (40217857)
MASUDA Yoshihisa Communications Reserch Laboratory, Okinawa Radio Observatory, Chief, 通信総合研究所・沖縄電波観測所, 所長
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| Project Period (FY) |
1994 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥18,100,000 (Direct Cost: ¥18,100,000)
Fiscal Year 1996: ¥4,400,000 (Direct Cost: ¥4,400,000)
Fiscal Year 1995: ¥7,700,000 (Direct Cost: ¥7,700,000)
Fiscal Year 1994: ¥6,000,000 (Direct Cost: ¥6,000,000)
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| Keywords | RASS / Temperature / Troposphere / Radar / Remote-sensing / Atmosphere dynamics / Acoustic wave / Array-antena / 大気温度プロファイル / MUレーダー / 電波屈折率 / 音波発射装置 / 音響ホーン |
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| Research Abstract |
We have been developed a high-power acoustic transmitter system for a RASS (Radio Acoustic Sounding System) which is a remote-sensing technique for obtaining temperature profiles in the troposphere and lower stratosphere with good accuracy and timeheight resolutions.
First, we examined a specification of the new acoustic transmitter system of the MU radar required for the observations up to the lower stratosphere, and determined to build up an active phased-array system consisting of 20 electro-dynamic horn speakers surrounding the MU radar.
Maximum acoustic output of an electro-dynamic horn speaker reached 140 dB exceeding the required acoustic power. We have also obtained a high acoustic efficiency of 32% by applying a hyperbolic horn. By using the new system, we were successful to observe temperature and wind velocity profiles from 1.5km to 18km altitudes.
Further, we steered an acoustic beam formed by a few speakers and analyzed a profile of signal to noise ratios (SNR). The SNR profile indicated that RASS echoes scattered by the acoustic waves from different sources were in-phase and enhanced receiving signal power in a height region expected by the result of ray-tracing of the acoustic waves, which confirmed that the active phased-array system worked correctly.
By monitoring detailed structures of meso-and micro-scale phenomena with high time-height resolutions by the RASS developed in this research, we expect to obtain new scientific aspects of mechanisms of the phenomena, and characteristics of various atmospheric waves excited by them.
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