Diagnostics of diapycnal diffusion in z-level ocean models
Diagnostics of diapycnal diffusion in z-level ocean models
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DOI：
10.1016/j.ocemod.2011.11.006
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发表时间：
2008-03
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影响因子：
--
通讯作者：
J. Getzlaff
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文献类型：
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作者：
J. Getzlaff
我们提出了一个强大的方法诊断总diapycnal扩散系数，即明确应用加上数值诱导扩散系数，从示踪剂释放实验中的数值z-水平模型。在这个意义上，分析和比较了仅在所用平流方案上不同的数值试验（CTRD使用二阶中心差分，UPWIND使用逆风/上游平流方案，QUICK使用Farrow和Stevens（1995）之后的更快平流方案，FCT使用Gerdes等人（1991）之后）。为了获得区域解决的估计diapycnal diffusivities，个别惰性染料示踪剂被释放在动态不同地区的北大西洋模型，即（i）在内部的副热带环流和（ii）在西部边界电流。诊断扩散率是强大的模拟染料示踪剂的平流方案和两个区域的时间和空间采样的变化。数值诱导的扩散率一般是积极的，但可以成为负面的中心差异平流数值几个月后，模拟示踪剂分散。
We present a robust method for diagnosing total diapycnal diffusivities, i.e. explicitly applied plus numerically induced diffusivities, from tracer release experiments in numerical z-level models. To this extent, numerical experiments differing only in the advection scheme used (CTRD using 2nd order centred differences, UPWIND using the upwind/upstream advection scheme, QUICK using the quicker advection scheme after Farrow and Stevens (1995) and FCT after Gerdes et al. (1991)) are analysed and compared. To obtain regionally resolved estimates of diapycnal diffusivities, individual inert dye tracers are released in dynamically different regions of a North Atlantic model, namely (i) in the interior of the subtropical gyre and (ii) in the western boundary current. Diagnosed diffusivities are robust with respect to changes in temporal and spatial sampling of the simulated dye tracer for both advection schemes and for both regions. The numerically induced diffusivity is generally positive, but can become negative for centred differences advection numerics after several months of simulated tracer dispersion.