Rossby wave propagation on potential vorticity fronts with finite width
Rossby wave propagation on potential vorticity fronts with finite width
复制标题
罗斯贝波在有限宽度位涡锋上的传播
DOI：
10.1017/jfm.2016.180
复制
发表时间：
2016
影响因子：
3.7
通讯作者：
M. Ambaum
中科院分区：
文献类型：
--
作者：
B. Harvey;J. Methven;M. Ambaum
在全球数值天气预报中，对流层顶的位涡（PV）水平梯度通常随着预报提前时间的增加而下降，并趋于稳定值，这取决于模式的分辨率。本文探讨如何传播对流层顶PV对比度在一个更广泛的锋区影响Rossby波的传播。所采取的方法是在一个简单的单层模型中分析Rossby波的PV前的有限宽度。线性Rossby波的色散关系的PV前的无限小的宽度是众所周知的，在这里，近似校正推导出的情况下，有限宽度的前，有效的限制，前是窄的带状波长。扩大前导致射流速度和波的上游传播能力下降。这些变化对Rossby波相速度的贡献在首阶处抵消。在二阶，射流速度的降低占主导地位，这意味着相速度在更宽的PV前沿上较慢。这种渐近相速度的结果被证明持有广泛的一类单层动态PV反演算子的变化范围。相速度对锋面宽度的依赖性通过数值模拟进行了验证，并且在有限波振幅下也表现出稳健性，并且估计了由于数值天气预报模型中存在的PV梯度误差而导致的Rossby波传播速度的误差。
The horizontal gradient of potential vorticity (PV) across the tropopause typically declines with lead time in global numerical weather forecasts and tends towards a steady value dependent on model resolution. This paper examines how spreading the tropopause PV contrast over a broader frontal zone affects the propagation of Rossby waves. The approach taken is to analyse Rossby waves on a PV front of finite width in a simple single-layer model. The dispersion relation for linear Rossby waves on a PV front of infinitesimal width is well known; here, an approximate correction is derived for the case of a finite-width front, valid in the limit that the front is narrow compared to the zonal wavelength. Broadening the front causes a decrease in both the jet speed and the ability of waves to propagate upstream. The contribution of these changes to Rossby wave phase speeds cancel at leading order. At second order the decrease in jet speed dominates, meaning phase speeds are slower on broader PV fronts. This asymptotic phase speed result is shown to hold for a wide class of single-layer dynamics with a varying range of PV inversion operators. The phase speed dependence on frontal width is verified by numerical simulations and also shown to be robust at finite wave amplitude, and estimates are made for the error in Rossby wave propagation speeds due to the PV gradient error present in numerical weather forecast models.
罗斯贝波结构的系统模型预报误差
影响因子：
5.2
作者：
Gray S
通讯作者：
Gray S
有限厚度对流层顶的准地转动力学
影响因子：
3.1
作者：
Plougonven R
通讯作者：
Plougonven R
斜压初值问题的解释：具有非零内部 PV 梯度的简单基本状态的结果
影响因子：
3.1
作者：
Frame T
通讯作者：
Frame T