Interannual variations of the mean wind and gravity wave variances in the middle atmosphere over Hawaii
Interannual variations of the mean wind and gravity wave variances in the middle atmosphere over Hawaii
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DOI：
10.1016/j.jastp.2004.01.015
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发表时间：
2004-04
影响因子：
1.9
通讯作者：
N. Gavrilov;D. Riggin;D. Fritts
中科院分区：
文献类型：
--
作者：
N. Gavrilov;D. Riggin;D. Fritts
Using simple numerical filters, wind variances with time scales of 0.1 – 1 h and 1 – 5 h are estimated from medium frequency radar wind observations at altitudes 70 – 94 km over Hawaii (22°N, 160°W) during the years 1990–2000. The results show interannual variations of the mean wind and variances. The variances can be attributed to the presence of atmospheric gravity waves (GWs). At altitudes below 80 km a maximum of GW intensity was observed between the years 1992 and 1996. An average seasonal cycle in wind variances is calculated by compositing over the 11 years of data. The monthly residual values, obtained after subtraction of the average seasonal variations show quasi-biennial (∼27 month) and longer period oscillations. Maximum variances are observed in 1993 and 1998–1999 at altitudes above ∼84 km . A correlation is found between GW wind variances and the Southern Oscillation Index, which in turn reflects El Niño activity in the tropical Pacific. However, more analysis with several El Niño events is required to establish the correlation with greater confidence.
