A method to reduce the spin-up time of ocean models   总被引：2，自引：2，他引：0  

Erik Bernsen  Henk A. Dijkstra  Fred W. Wubs 《Ocean Modelling》2008,20(4):380-392

The spin-up timescale in large-scale ocean models, i.e., the time it takes to reach an equilibrium state, is determined by the slow processes in the deep ocean and is usually in the order of a few thousand years. As these equilibrium states are taken as initial states for many calculations, much computer time is spent in the spin-up phase of ocean model computations. In this note, we propose a new approach which can lead to a very large reduction in spin-up time for quite a broad class of existing ocean models. Our approach is based on so-called Jacobian–Free Newton–Krylov methods which combine Newton’s method for solving non-linear systems with Krylov subspace methods for solving large systems of linear equations. As there is no need to construct the Jacobian matrices explicitly the method can in principle be applied to existing explicit time-stepping codes. To illustrate the method we apply it to a 3D planetary geostrophic ocean model with prognostic equations only for temperature and salinity. We compare the new method to the ‘ordinary’ spin-up run for several model resolutions and find a considerable reduction of spin-up time.  相似文献   

Overbank sand deposition in relation to transport volumes during large-magnitude floods in the Dutch sand-bed Rhine river system     

Wilfried B. M. Ten Brinke  Margriet M. Schoor  Anne M. Sorber  Henk J. A. Berendsen 《地球表面变化过程与地形》1998,23(9):809-824

Using aerial photographs and field measurements, sandy overbank deposits formed by the large-magnitude floods of 1993/94 and 1995 were quantified along two branches of the Dutch Rhine river system: the Waal (1993/94 and 1995) and the IJssel (1995). These deposits were laid down intermittently all along the length of these rivers on the top and landward slope of the natural levees, and covered about 4 per cent of the embanked floodplain on the Waal and about 1 per cent on the IJssel. The overbanks and transport mechanism is basically convective by nature. The spatial variability of overbank sedimentation points to the important role played by helicoidal currents in determining overbank deposition. The presence of embankments and training works appears to influence the sand transport to and morphological development of the floodplains along the Dutch Rhine river system. Overbank deposition volumes about equal present estimates of sand transport during a large-magnitude flood. It appears that studies on sand transport in the Dutch Rhine carried out so far underestimate sand transport during floods. © 1998 John Wiley & Sons, Ltd.  相似文献   

Measurement and modelling evaporation for irrigated crops in north-west Mexico     

Jaime Garatuza-Payan  W. James Shuttleworth  David Encinas  David D. McNeil  John B. Stewart  Henk deBruin  Christopher Watts 《水文研究》1998,12(9):1397-1418

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