Numerical modeling of the global semidiurnal tide in the present day and in the last glacial maximum
Numerical modeling of the global semidiurnal tide in the present day and in the last glacial maximum
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DOI：
10.1029/2003jc001973
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发表时间：
2004-03-02
影响因子：
3.6
通讯作者：
Bills, BG
中科院分区：
文献类型：
--
作者：
Egbert, GD;Ray, RD;Bills, BG
本文采用一种水动力模型，结合海洋自吸引和载荷（SAL）的自洽处理，以及基于物理的内潮（IT）阻力参数化，来评估在没有数据的情况下，正压潮模型的准确性，并探索末次盛冰期（LGM）的潮汐能量学。采用现代测深技术以高分辨率计算的M-2解与卫星测高得到的开阔海洋中RMS在5厘米以内的高度估计值一致。只有在模型中包括SAL和IT阻力时，才能达到这种精度，并与非平衡能量耗散估计相一致。解决方案对测深扰动很敏感，现有全球数据库的不准确性可能是模拟高程中剩余误差的主要原因。在LGM期间，海平面下降了大约100米，导致模拟的M2潮汐发生了显著变化，北大西洋的一些振幅增加了2倍或更多。海面的下降也显著地改变了消散。如果假设现代海洋的IT阻力估算值，则全球耗散增加约50%，在深海中几乎增加三倍。然而，IT阻力取决于海洋分层，这对于LGM来说知之甚少。修正IT阻力的试验表明，耗散整体增加的趋势是一个可靠的结果，但细节对分层很敏感。因此，即使在这种相对简单的情况下，在水深测量受到严格限制的情况下，关于古潮汐的重大不确定性仍然存在。
[1] A hydrodynamic model incorporating a self-consistent treatment of ocean self-attraction and loading ( SAL), and a physically based parameterization of internal tide ( IT) drag, is used to assess how accurately barotropic tides can be modeled without benefit of data, and to explore tidal energetics in the last glacial maximum (LGM). M-2 solutions computed at high resolution with present day bathymetry agree with estimates of elevations from satellite altimetry within 5 cm RMS in the open ocean. This accuracy, and agreement with atlimetric estimates of energy dissipation, are achieved only when SAL and IT drag are included in the model. Solutions are sensitive to perturbations to bathymetry, and inaccuracies in available global databases probably account for much of the remaining error in modeled elevations. The approximate to100 m drop in sea level during the LGM results in significant changes in modeled M2 tides, with some amplitudes in the North Atlantic increasing by factors of 2 or more. Dissipation is also significantly changed by the drop in sea level. If IT drag estimated for the modern ocean is assumed, dissipation increases by about 50% globally, and almost triples in the deep ocean. However, IT drag depends on ocean stratification, which is poorly known for the LGM. Tests with modified IT drag suggest that the tendency to a global increase in dissipation is a robust result, but details are sensitive to stratification. Significant uncertainties about paleotides thus remain even in this comparatively simple case where bathymetry is well constrained.