Impact of a Stochastic Nonorographic Gravity Wave Parameterization on the Stratospheric Dynamics of a General Circulation Model
Impact of a Stochastic Nonorographic Gravity Wave Parameterization on the Stratospheric Dynamics of a General Circulation Model
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DOI：
10.1029/2018ms001297
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发表时间：
2018-09
影响因子：
6.8
通讯作者：
F. Serva;C. Cagnazzo;Angelo Riccio;E. Manzini
中科院分区：
文献类型：
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作者：
F. Serva;C. Cagnazzo;Angelo Riccio;E. Manzini
中层大气，特别是中间层的总体环流强烈依赖于重力波过程产生的强迫。它们在对流层的来源既有地形来源，也有非地形来源，后者具有很强的间歇性。在气候模型中，重力波的影响需要参数化，通常假设其属性是恒定的。在这项工作中，我们使用海因斯方案的随机版本，重点关注由于在非地形重力波参数化中引入间歇性而导致的中层大气的变化。随机方法是根据模型对这种强迫的诊断敏感性而定制的，即使规定了相对少量的间歇性，也会出现特殊的变化。我们详细分析了当采用随机参数化代替确定性参数化时，热带地区平流层动力学和平流层动力学和中层大气全球环流的变化。当添加随机性时，模型的平均状态和变异性（在默认版本中也是现实的）将被保留。由于向极地输送的增强，中间层发生了显着变化，导致冬季变暖。虽然平均状态有所改善，但温带地区的年际变化并未受到显着影响。对模拟赤道平流层的影响是显而易见的，因为随机性减少了准两年一次振荡的总体周期，但也导致周期之间变异性的净减少。
The general circulation of the middle atmosphere, particularly of the mesosphere, is strongly dependent on the forcing arising from gravity wave processes. Their sources in the troposphere are both orographic and nonorographic, the latter being strongly intermittent. In climate models, the effects of gravity waves need to be parameterized, often assuming that their properties are constant. In this work we focus on the changes of the middle atmosphere due to the introduction of intermittency in a parameterization of nonorographic gravity waves, using a stochastic version of the Hines scheme. The stochastic approach is tailored to the diagnosed sensitivity of the model to this forcing, and peculiar changes emerge even if a relatively small amount of intermittency is prescribed. We analyze in detail the changes of the stratospheric dynamics in the tropical region and the global circulation of the middle atmosphere, when the stochastic parameterization is employed in place of the deterministic one. The mean state and variability of the model, realistic also in the default version, are preserved when stochasticity is added. Significant changes are observed in the mesosphere due to an enhanced poleward transport, leading to warming in the winter season. While there are some improvements of the mean state, the interannual variability is not significantly affected in the extratropics. The impacts on the simulated equatorial stratosphere are evident, as the stochasticity reduces the overall period of the quasi‐biennial oscillation but also leads to a net reduction of the variability between cycles.