P-Vector Method for Determining Absolute Velocity From Hydrographic Data
P-Vector Method for Determining Absolute Velocity From Hydrographic Data
复制标题
DOI：
--
复制
发表时间：
1989
影响因子：
0.8
通讯作者：
P. Chu
中科院分区：
文献类型：
--
作者：
P. Chu
已发展起来的几种主要技术(Stommel-Schott方法、Wunsch方法和Bernoulli方法)已被开发用于在参考水平上定量估计地转速度，它们具有相同的动力学复杂性(地转、流体静力和密度守恒)。从技术角度看，Stommel-Schott方法是一个超定系统(方程数目远远大于变量数目)，而Wunsch方法是一个欠定系统(方程数目远远小于变量数目)。基于相同的动力学和热力学框架，本研究提出了一个简单、适定的系统(P-矢量法)。与地转一致，系统被假定为非耗散的。质量守恒和位涡守恒导致速度矢量垂直于密度(ρ)和位涡(Q=f∂ρ/∂z)梯度，并且速度可以表示为V(x，y，z)=r(x，y，z)P(x，y，z)，其中P=(⊇ρx⊇Q)/|⊇ρx⊇Q|。单位向量P是由密度场计算出来的，参数r(x，y，z)由热风关系决定。此外，本研究还提出了一种减少误差的方案。
Several major techniques (Stommel-Schott method, Wunsch method, and Bernoulli method) that have been developed to quantitatively estimate the geostrophic velocity at the reference level, have the same order of dynamical sophistication (geostrophy, hydrostatic, and density conservation.) From a technical point of view, the Stommel-Schott method is an overdetermined system (the number of equations is much larger than the number of variables), however, the Wunsch method is an underdetermined system (the number of equations is much smaller than the number of variables). Based on the same dynamical and thermodynamical framework, a simple, well-posed system (P-vector method) is proposed in this study. Consistent with geostrophy, the system is assumed non-dissipative. The conservation of mass and potential vorticity leads to the condition that the velocity vector is perpendicular to both density (ρ) and potential vorticity (q = f∂ρ/∂z) gradients, and that the velocity can be represented as V(x, y, z) = r(x, y, z)P (x, y, z), where P = (⊇ρ x ⊇q)/|⊇ρ x ⊇q|. The unit vector, P, is computed from the density field, and the parameter r(x, y, z) is determined by the thermal-wind relation. Furthermore, an error reduction scheme is also proposed in this study.