2007 Fiscal Year Final Research Report Summary
Development of the evaluation technique on diffusion coefficient of snowpack for carbon dioxide using acoustical property
| Project/Area Number |
17540421
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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 |
Meteorology/Physical oceanography/Hydrology
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| Research Institution | National Agricultural Research Organization |
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Principal Investigator |
KOMINAMI Yasuhiro National Agricultural Research Organization, National Agricultural Research Center Research Team for Weather-related Risk Management System, Senior researcher (00370544)
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| Co-Investigator(Kenkyū-buntansha) |
YOKOYAMA Kotaro National Agriculture and Food Research Organization, National Agricultural Research Center Research Team for Weather-related Risk Management System, Chief Researcher (30355599)
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| Project Period (FY) |
2005 – 2007
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| Keywords | carbon dioxide / snowpack / sound velocity / acoustic attenuation coefficient / gas diffusivity |
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| Research Abstract |
1. Sound velocity and the acoustic attenuation coefficient of the snowpack of various snow conditions were measured, and relation between physical properties of snow and acoustical property were examined. The sound source used are sine wave from 200Hz to 8000Hz every 1/3 octaves.
(1) The sound velocity of the air of the snowpack depends on the winding level of the diffusion mute just like the gas diffusion coefficient. However it has been understood that the sound passes the beeline in the winding space while the gas diffusion coefficient depends on the mean distance of the winding space.
(2) The acoustic attenuation coefficient that spread in the space air was in inverse proportion to the square of the space sire, and it was confirmed that it was a phenomenon similar to the attenuation of the mass flow in the space caused by the pressure fluctuation. And the acoustic attenuation coefficient of the uniting snow particles is in inverse proportion to the snow density, and guessed to be the one by the mechanism of the interception by the effect of mass to the damping coefficient of the spreading sound.
2. The carbon dioxide concentration was continuously measured in three depth of the natural snowfall, and the phenomenon of the gas diffusivity of the appearance of the snow in the vicinity of the surface increasing by the wind was confirmed. From the above result, the sound velocity and the acoustic attenuation coefficient of the snowpack are related to the character to decide the gaseous environment of the snowpack..
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Research Products
(14 results)
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[Presentation] 積雪層内の音速度測定2008
Author(s)
小南靖弘・横山宏太郎
Organizer
雪氷研究東京大会
Place of Presentation
東京都
Year and Date
2008-09-26
Description
「研究成果報告書概要(和文)」より
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