| Cause of winter gravity wave spectrum saturation |
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| 作者姓名： | WU Yongfu & XU Jiyao Laboratory for Space Weather Center for Space Science and Applied Research Chinese Academy of Sciences Beijing China |
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| 作者单位： | WU Yongfu & XU Jiyao Laboratory for Space Weather，Center for Space Science and Applied Research，Chinese Academy of Sciences，Beijing 100080，China |
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| 基金项目： | 国家自然科学基金，国家重点基础研究发展计划(973计划) |
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| 摘 要： | Gravity waves play a significant role in establishing the large-scale circulation and structure of the middle atmosphere. Through gravity wave saturation proc-esses, such motions are believed to cause turbulence, resulting in divergence of momentum flux and the diffusion of heat and constituents in the meso-sphere1,2]. The mechanisms that contribute signifi-cantly to the gravity wave saturation are thought to be the dynamical and convective instabilities3]. However, it is difficult to distin…
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Cause of winter gravity wave spectrum saturation |
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| WU Yongfu & XU Jiyao Laboratory for Space Weather,Center for Space Science and Applied Research,Chinese Academy of Sciences,Beijing ,China.Cause of winter gravity wave spectrum saturation[J].Science in China(Earth Sciences),2005,48(10). |
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| Authors: | WU Yongfu XU Jiyao |
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| Institution: | Laboratory for Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100080, China |
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| Abstract: | This paper utilizes horizontal velocity measurements observed from 19 chaff rockets and nearly simultaneous temperature measurements collected from 19 falling sphere rockets to study the cause of winter gravity wave spectrum saturation. Results suggest that strong hori-zontal velocity shears larger than 0.04 s?1 are observed to be present at various heights near the winter mesopause. On one single chaff rocket flight, an extremely strong horizontal velocity shear as high as 0.33 s?1 is observed at 87.4 km and is believed to be the strongest value ever meas-ured in the mesosphere. These strong horizontal velocity shears, together with Brunt-V?is?l? frequency squared obtained from the temperature profile, act collectively to yield two dynamical instability regions of Richardson number smaller than 1/4, suggesting that the saturated gravity wave spectrum observed by the chaff rockets in winter is a result of dynamical instability. |
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| Keywords: | winter spectrum strong shear dynamical instability spectrum saturation |
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