The spontaneous generation of inertia-gravity waves during frontogenesis forced by large strain: numerical solutions
The spontaneous generation of inertia-gravity waves during frontogenesis forced by large strain: numerical solutions
复制标题
大应变迫使锋生过程中惯性重力波的自发产生：数值解
DOI：
10.1017/jfm.2015.197
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发表时间：
2015
影响因子：
3.7
通讯作者：
Shakespeare C
中科院分区：
文献类型：
--
作者：
Shakespeare C
利用一个完全非线性数值模式研究了水平应变场强迫下二维锋生过程中的自发波生成。该模型使用无限长直线锋面和均匀位涡的理想配置，并在锋面上施加均匀的收敛应变。Shakespeare & Taylor（J. Fluid Mech.，vol.757，2014，pp.817 -853）制定了用于该系统的广义分析模型（ST 14），其扩展了经典的霍斯金斯和Bretherton（J. Atmos.科学，第29卷，1972年，第11-37页）模型（HB）到大应变率（），二次循环的限制和波的自发产生，由ST 14预测，被证明是对HB解的重要修正。这些无粘预测也是强大的平衡前应变强迫锋生扩散平衡。对于强应变的波场成为领导阶的重要性的解决方案。在这种情况下，锋面环流被严格限制，垂直速度比HB模式大一个数量级。随着时间的推移而减弱的应变场的添加允许自发产生的波的释放和传播。我们还考虑了大涡度和应变率，超出ST 14模型的有效性的前。
A fully nonlinear numerical model is used to investigate spontaneous wave generation during two-dimensional frontogenesis forced by a horizontal strain field. The model uses the idealised configuration of an infinitely long straight front and uniform potential vorticity, with a uniform imposed convergent strain across the front. Shakespeare & Taylor (J. Fluid Mech., vol. 757, 2014, pp. 817–853) formulated a generalised analytical model (ST14) for this system that extends the classical Hoskins & Bretherton (J. Atmos. Sci., vol. 29, 1972, pp. 11–37) model (HB) to large strain rates (), the confinement of the secondary circulation and the spontaneous generation of waves, predicted by ST14, are shown to be important corrections to the HB solution. These inviscid predictions are also robust for an equilibrated front where strain-forced frontogenesis is balanced by diffusion. For strong strains the wavefield becomes of leading-order importance to the solution. In this case the frontal circulation is tightly confined, and the vertical velocity is an order of magnitude larger than in the HB model. The addition of a strain field that weakens with time allows the release and propagation of the spontaneously generated waves. We also consider fronts with both large vorticity and strain rate, beyond the validity of the ST14 model.