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标题：On the variability of the seasonal scale oscillations over Cachoeira Paulista (22.7°S, 45°W), Brazil
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作者：Amitava Guharay ; Paulo Prado Batista ; Barclay Robert Clemesha 等
期刊名称：Earth, Planets and Space
电子版ISSN：1880-5981
出版年度：2014
卷号：66
期号：1
页码：1-11
DOI：10.1186/1880-5981-66-45
出版社：Springer Verlag
摘要：The characteristics of long period atmospheric oscillations are studied using long-term meteor radar wind observations over a low-latitude Brazilian station, Cachoeira Paulista (22.7°S, 45°W).The semiannual oscillation (SAO) amplitude decreases gradually with altitude in the mesopause region, while the annual oscillation (AO) amplitude exhibits a minimum at mid-mesopause with significant interannual variability.The quasi-biennial oscillation (QBO) obtained by removing the SAO and AO from the zonal wind exhibits an out-of-phase relationship at lower mesopause heights (approximately 81 km) and mid-stratosphere (approximately 10 hPa).There is an evident signature of modulation of the mesospheric SAO (MSAO) and mesospheric AO (MAO) by the QBO.The diurnal tide is surmised to contribute significantly to drive the easterly phase of these oscillations, especially MSAO and MAO through depositing westward momentum to the background wind.The westerly phase of the MSAO is believed to support the growth of the quasi-2-day wave (QTDW) by wave filtering.The QTDW is found to be strong during the easterly phase of the MAO indicating a possible existence of the barotropic/baroclinic instability during summer and a possible role of the QTDW towards westward forcing of the background wind.
关键词：Seasonal oscillations ;Diurnal tide ;Quasi-2-day wave