A Diagnostic Formulation for Wave-Mean Flow Interactions and Lagrangian-Mean Circulation with a Hybr
A Diagnostic Formulation for Wave-Mean Flow Interactions and Lagrangian-Mean Circulation with a Hybr
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波平均流相互作用和拉格朗日平均环流的混合诊断公式
DOI：
10.2151/jmsj1965.67.2_293
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发表时间：
1989
影响因子：
3.1
通讯作者：
T. Iwasaki
中科院分区：
文献类型：
--
作者：
T. Iwasaki
提出了一种诊断有限振幅非地转系统内波-平均流相互作用和拉格朗日平均经向环流的新公式。在该方案中，垂直坐标由沿等熵面的纬向平均压力定义，所有代表纬向平均场的变量都用与两个等熵面的空气质量成比例的归一化权重平均。虽然纬向平均动量、连续性和热力学方程的表述方式与Andrews和McIntyre的变换欧拉平均（p-TEM）方程类似，但新格式的热力学方程没有涡流项。这使得修正经向环流中有限振幅扰动的“斯托克斯漂移”成为可能。利用NCAR社区气候模式的永久一月运行，初步诊断研究证明了新方案的实际优势。与p-TEM的比较表明，质量流函数的经向截面和Eliassen-Palm通量散度有很大的不同。特别是，用新方案得到的质量流函数在平流层下层形成一个半球单细胞环流（即所谓的Brewer-Dobson环流）。作为新坐标系的进一步应用，我们建立了二维轴对称示踪输运方程，其中由绝热运动引起的扩散由一个仅包含一个自变量的对称张量表示。
A new formulation is proposed to diagnose wave-mean flow interactions and Lagrangian-mean meridional circulations within a finite amplitude nongeostrophic system. In this scheme, the vertical coordinate is defined by the zonally averaged pressure along isentropic surfaces and all variables representing zonal mean fields are averaged with normalized weights proportional to the mass of air between two isentropic surfaces. Although the zonally averaged momentum, continuity and thermodynamic equations are formulated in a way similar to the transformed Eulerian mean (p-TEM) equations by Andrews and McIntyre, the thermodynamic equation of the new scheme does not have eddy terms. This makes it possible to correct for `Stokes drift' in meridional circulations for finite amplitude disturbances. Using a perpetual January run of the NCAR community climate model, a preliminary diagnostic study demonstrates a practical advantage of the new scheme. Comparisons of the new scheme with the p-TEM show considerable differences in meridional cross sections of the mass streamfunctions and the Eliassen-Palm flux divergence. In particular, the mass streamfunction obtained with the new scheme forms a hemispheric single cell circulation in the lower stratosphere (the so-called Brewer-Dobson circulation). As a further application of the new coordinate system, a two dimensional axisymmetric tracer transport equation is formulated, where diffusion due to adiabatic motions is expressed by a symmetric tensor involving only one independent variable.