Observations and simulations of a large-amplitude mountain wave breaking over the Antarctic Peninsula
Observations and simulations of a large-amplitude mountain wave breaking over the Antarctic Peninsula
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DOI：
10.1029/2007jd009739
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发表时间：
2008-08
影响因子：
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通讯作者：
R. Plougonven;A. Hertzog;H. Teitelbaum
中科院分区：
文献类型：
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作者：
R. Plougonven;A. Hertzog;H. Teitelbaum
[1] 基于 Vorcore 气球活动的观测和中尺度数值模拟，提出了南极半岛上发生的大振幅地形重力波的案例研究。 Vorcore活动（2005年9月至2006年2月）包括从2005年9月至2006年2月，27个超压气球在南半球平流层极涡核心高度16至19公里处飞行。2005年10月7日，其中一个气球在南极半岛上空飞行时爆炸。同一时间段在半岛上空飞行的另一个气球收集的观测结果表明，存在非常强烈的重力波（纬向和经向速度扰动的峰峰值幅度约为 25-30 m s−1）。由于其固有频率高，波包在气球观测中可能采样不足，但气球数据集得到了利用天气研究和预报模型进行的高分辨率数值模拟的补充。通过与气球测量进行比较来验证模拟结果，并表明在气球爆炸的时间和高度，波在平流层下部破裂。模拟强调了山波对平流层的几个影响：平均流的强迫、次级惯性重力波的产生以及湍流和混合。特别是，计算了动量通量，发现其与气球测量的估计值非常吻合。发现的大值可能是极值，这引发了它们的代表性问题。为了讨论这个问题，气球测量与操作分析结合使用来估计这种大振幅重力波的频率，即提供对其间歇性的估计。
[1] A case study of a large-amplitude orographic gravity wave occurring over the Antarctic Peninsula is presented, based on observations from the Vorcore balloon campaign and on mesoscale numerical simulations. The Vorcore campaign (September 2005 to February 2006) consisted in the flight of 27 superpressure balloons in the core of the Southern Hemisphere stratospheric polar vortex at altitudes of 16–19 km, from September 2005 to February 2006. On 7 October 2005, one of the balloons exploded as it was flying above the Antarctic Peninsula. The observations collected by another balloon that was flying during the same time period above the peninsula suggest the presence of a very intense gravity wave (peak-to-peak amplitude of the order of 25–30 m s−1 in zonal and meridional velocity disturbances). The wave packet is likely undersampled in the balloon observations because of its high intrinsic frequency, but the balloon data set is complemented with high-resolution numerical simulations carried out with the Weather Research and Forecast Model. The simulations are validated by comparison with the balloon measurements and show that the wave was breaking in the lower stratosphere at the time and height where the balloon exploded. The simulations highlight several consequences of the mountain wave on the stratosphere: forcing of the mean flow, generation of secondary inertia-gravity waves, and turbulence and mixing. In particular, the momentum fluxes are calculated and are found to compare well with the estimates from balloon measurements. The large values found are likely extreme values, which raises the issue of their representativity. To discuss this, the balloon measurements are used in conjunction with operational analyses to estimate the frequency of such large-amplitude gravity waves, i.e., to provide an estimate of their intermittency.