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| An investigation of the atmospheric wave dynamics in the polar region using ground based instruments | |
| Khanyile;Bhekumuzi Sfundo | |
| 出版年 | 2011 |
| 学位授予单位 | University of Fort Hare, Faculty of Science & Agriculture |
| 英文摘要 | Abstract This study presents the characteristics of small-scale gravity waves in the mesosphere region as derived from the imaging riometer data at high altitude (~90 km) over SANAE (72˚S, 3˚W). Wavelet analysis and FFT (Fast Fourier transform) have been applied to extract short period gravity wave parameters for the year 2000. The horizontal wavelength, phase speed and observed period of gravity waves are typically 10-100 km, 5-60 m.s-1 and 3-60 minutes, respectively. The horizontal propagation direction is north-eastward throughout the year. This could probably be due to selective filtering by the zonal wind. Zonal and meridional winds in the region of the MLT (mesosphere and lower thermosphere) have been measured using HF radars at high latitudes in the southern hemisphere. Data from January 2000 to December 2003 have been used with the aim of investigating the characteristics of planetary wave activity at ~90 km. For SANAE and Halley stations, 2-, 5-, 10-, 16- and 20-day planetary waves are dominant in summer and winter. The results show the seasonal variations of the mean winds, which are caused by the internal variability of the quasi stationary planetary waves. Planetary wave coupling processes between UKMO assimilated and mesospheric data have also been investigated. The cross wavelet results show a strong coupling during winter months. The results suggest that planetary waves are generated at lower atmospheric heights and propagate upwards into mesospheric heights. However, not all observed disturbances in mesospheric heights can be explained by the propagation of planetary waves from lower atmospheric heights. |
| 英文关键词 | Gravity waves Atmospheric physics -- South Africa Riometer Gravity -- Measurement Rossby waves |
| 语种 | 英语 |
| URL | http://hdl.handle.net/10353/447 |
| 来源机构 | University of Fort Hare |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/246141 |
| 推荐引用方式 GB/T 7714 | Khanyile;Bhekumuzi Sfundo. An investigation of the atmospheric wave dynamics in the polar region using ground based instruments[D]. University of Fort Hare, Faculty of Science & Agriculture,2011. |
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