Frequency variations of gravity waves interacting with a time-varying tide
Frequency variations of gravity waves interacting with a time-varying tide
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DOI：
10.5194/angeo-31-1731-2013
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发表时间：
2013-10
影响因子：
1.9
通讯作者：
Chunming Huang;S. Zhang;F. Yi;K. Huang;Yehui Zhang;Q. Gan;Yun Gong
中科院分区：
文献类型：
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作者：
Chunming Huang;S. Zhang;F. Yi;K. Huang;Yehui Zhang;Q. Gan;Yun Gong
抽象的。利用非线性二维时变数值模式，模拟了重力波在时变潮汐中的传播。我们的模拟结果表明，当一个GW数据包传播在一个时变的潮汐风环境中，不仅其固有频率，而且其地基频率会发生显着变化。潮汐水平风加速度主导GW频率变化。正（负）加速度引起频率随时间增加（减小）。更有趣的是，在临界层附近的潮汐风加速总是导致GW频率增加，这可能部分地解释了高频GW分量在中高层大气中比在低层大气中更占主导地位的观测结果。在随时间变化的潮汐风场和瞬态性质的临界层引起的随时间变化的潮汐纬向风的组合增加的地面传播的GW的频率创造了有利的条件，GW穿透其原来预期的临界层。因此，全球变暖对背景大气的影响比预期的要高得多，这表明潮汐-全球变暖相互作用的动力学效应比全球模式中通常考虑的全球变暖参数化更为复杂。
Abstract. Using a nonlinear, 2-D time-dependent numerical model, we simulate the propagation of gravity waves (GWs) in a time-varying tide. Our simulations show that when a GW packet propagates in a time-varying tidal-wind environment, not only its intrinsic frequency but also its ground-based frequency would change significantly. The tidal horizontal-wind acceleration dominates the GW frequency variation. Positive (negative) accelerations induce frequency increases (decreases) with time. More interestingly, tidal-wind acceleration near the critical layers always causes the GW frequency to increase, which may partially explain the observations that high-frequency GW components are more dominant in the middle and upper atmosphere than in the lower atmosphere. The combination of the increased ground-based frequency of propagating GWs in a time-varying tidal-wind field and the transient nature of the critical layer induced by a time-varying tidal zonal wind creates favorable conditions for GWs to penetrate their originally expected critical layers. Consequently, GWs have an impact on the background atmosphere at much higher altitudes than expected, which indicates that the dynamical effects of tidal–GW interactions are more complicated than usually taken into account by GW parameterizations in global models.