The 5-day wave in the Arctic and Antarctic mesosphere and lower thermosphere
The 5-day wave in the Arctic and Antarctic mesosphere and lower thermosphere
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DOI：
10.1029/2009jd012545
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发表时间：
2010-01
影响因子：
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通讯作者：
K. Day;N. Mitchell
中科院分区：
文献类型：
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作者：
K. Day;N. Mitchell
[1]利用北极Esrange（北纬68度，东经21度）和南极Rothera（南纬68度，西经68度）的流星雷达对极地中层和低热层的5天行星波进行了研究。测量时间间隔分别为1999年10月至2008年12月的9年和2005年2月至2008年12月的4年。覆盖的高度范围约为80-100公里。水平风的变化在4-7天的波周期范围内被用作代理的5天波的活动。在冬季和夏末可以看到强烈的波浪活动。然而，有一个高度的年际变化，在某些个别年份波活动几乎是不存在的。这些数据被用来构建北极和南极的代表性气候学。在两个极地地区，5天波的季节性周期非常相似。冬季的波浪活动存在于整个观测高度范围内。冬季波浪方差可达65 m2/s2左右。在春分点左右，这种波动基本上不存在。波浪活动在夏末也非常强烈，达到约75 m2/s2，但只发生1-2个月，并限于约90 km以上的高度，并排除在较低高度的较强向西之外。夏季波活动在大约95公里的高度达到峰值，并在该高度以上和以下迅速衰减。在这个夏季极大期间，波不可能从下面上升到中间层和低热层，因此必须在原地产生和/或从冬季半球穿过赤道。5日波的季节循环与在这些纬度观测到的2日波非常相似。
[1] The 5-day planetary wave in the polar mesosphere and lower thermosphere has been investigated using meteor radars at Esrange (68°N, 21°E) in the Arctic and Rothera (68°S, 68°W) in the Antarctic. The measurements span the 9-year interval from October 1999 to December 2008 and the 4-year interval from February 2005 to December 2008, respectively. The height range covered is approximately 80–100 km. Horizontal wind variance within a wave period range of 4–7 days is used as a proxy for the activity of the 5-day wave. Strong wave activity is seen in winter and late summer. However, there is a high degree of interannual variability, and in some individual years wave activity is almost absent. The data are used to construct a representative climatology for the Arctic and Antarctic. The seasonal cycle of the 5-day wave is found to be very similar in both polar regions. Wave activity in winter is present across the entire height range observed. Wintertime wave variance can reach about 65 m2/s2. The wave is largely absent around the equinoxes. Wave activity is also very strong in late summer, reaching about 75 m2/s2, but occurs only for 1–2 months and is confined to heights above about 90 km and excluded from the stronger westward winds at lower heights. Summertime wave activity peaks at a height of about 95 km and decays rapidly above and below that height. During this summer maximum, the wave cannot have ascended to the mesosphere and lower thermosphere from below and so must have been generated in situ and/or ducted across the equator from the winter hemisphere. The seasonal cycle of the 5-day wave is remarkably similar to that observed for the 2-day wave at these latitudes.