Quasi‐geostrophic dynamics in the presence of moisture gradients
Quasi‐geostrophic dynamics in the presence of moisture gradients
复制标题
存在湿度梯度的准地转动力学
DOI：
10.1002/qj.2644
复制
发表时间：
2016
影响因子：
8.9
通讯作者：
J. Sukhatme
中科院分区：
文献类型：
--
作者：
J. Monteiro;J. Sukhatme
本文从中纬β平面上的旋转浅水方程组出发，导出了一个与水汽耦合的准地转系统。当某一点的湿度超过规定的饱和值时，就会发生冷凝。可以看出，需要一个缓慢的凝聚时间尺度来获得一组一致的方程。此外，由于平流风场是地转的，因此水分（以及降水）的变化仅通过非辐散机制发生。在观测之后，规定了在纬向和纬向方向上具有梯度的饱和度剖面。一个纯粹的纬向梯度有减缓干Rossby波的效果，通过减少的“等效梯度”的背景位涡。一个大尺度不稳定的湿模态会导致包含纬向梯度本身，或与纬向湿度梯度一起。对于代表大气的梯度，最不稳定的潮湿模式在纬向传播的方向上增加水分，在季节内时间尺度上成熟，并具有较小的相速度。
The derivation of a quasi‐geostrophic system from the rotating shallow‐water equations on a midlatitude β‐plane coupled with moisture is presented. Condensation is prescribed to occur whenever the moisture at a point exceeds a prescribed saturation value. It is seen that a slow condensation time‐scale is required to obtain a consistent set of equations at leading order. Further, since the advecting wind fields are geostrophic, changes in moisture (and hence precipitation) occur only via non‐divergent mechanisms. Following observations, a saturation profile with gradients in the zonal and meridional directions is prescribed. A purely meridional gradient has the effect of slowing down the dry Rossby waves, through a reduction in the ‘equivalent gradient’ of the background potential vorticity. A large‐scale unstable moist mode results on the inclusion of a zonal gradient by itself, or in conjunction with a meridional moisture gradient. For gradients that are are representative of the atmosphere, the most unstable moist mode propagates zonally in the direction of increasing moisture, matures over an intraseasonal time‐scale and has small phase speed.
使用罗斯贝波分量解释具有水分参数化效应的斜斜波
影响因子：
3.1
作者：
Frame T
通讯作者：
Frame T