Search Results

You are looking at 1 - 4 of 4 items for

  • Author or Editor: Yong Ming Tang x
  • Refine by Access: All Content x
Clear All Modify Search
Yong Ming Tang and Roger Grimshaw

Abstract

The authors use numerical simulations of the shallow-water equations to study the generation of coastally trapped waves by localized forcing mechanisms. The model parameters are chosen to be typical for coastal ocean situations. The waves are generated by various wind-stress forcing mechanisms typical of atmospheric fronts or tropical cyclones that travel either parallel or normal to the coast, or in a combination of both of these. Coastally trapped waves fall into three classes: superinertial edge waves, Kelvin waves, and subinertial shelf waves. Mode-fitting routines are described, which when applied to the model output enable one to identify the type and modal properties of the waves generated. The authors’ results show that for the typical wind stress forcing considered here, the generated wave field is dominated by low-mode shelf waves.

Full access
Yong Ming Tang and Malcolm J. Roberts

Abstract

Although the overflow and descent of cold, dense water across the Greenland–Iceland–Scotland ridge is the principal means for the maintenance of the thermohaline circulation in the North Atlantic Ocean, this feature is not adequately treated in global ocean numerical models. In this paper, a bottom boundary layer scheme is introduced into the HadCM3 coupled atmosphere–ocean–sea ice general circulation climate model, in order to give an improved representation of cold water formation in the North Atlantic Ocean. The scheme uses a simple terrain-following bottom boundary layer incorporated into the ocean general circulation model; only the tracer tendencies are evaluated in the bottom boundary layer, with the velocities taken from the near-bottom interior values. It is found that with the bottom boundary layer scheme, there are several significant effects on the deep water formation and flow. The overflow of dense water from the Nordic Seas into the North Atlantic Seas is improved with the introduction of the authors’ bottom boundary layer scheme. Further, the thermohaline circulation is reduced in strength, but is also deeper, when compared with simulations without any bottom boundary layer scheme. There is also a stronger flow along the northwestern boundary, a more southerly location of the North Atlantic Current, and a stronger and larger subpolar gyre. Overall, these effects are an improvement when compared with climatology, although some differences remain.

Full access
Yong Ming Tang, Peter Holloway, and Roger Grimshaw

Abstract

In 1983 Tropical Cyclone Jane crossed the North West Coast of Australia generating a storm surge. Currents associated with this storm surge were recorded at two offshore moorings south of the cyclone track. The data from these moorings are suggestive of the propagation of a continental shelf wave between the two stations. This hypothesis is tested by carrying out a numerical simulation of this storm surge based on the depth-integrated shallow-water equations, with wind-wave-enhanced bottom friction. Analysis of the numerical results shows that the storm surge can be interpreted as due to continental shelf waves.

Full access
Yong Ming Tang, Brian Sanderson, Greg Holland, and Roger Grimshaw

Abstract

A two-dimensional numerical model of the shallow-water equations, with a modified Orlanski-type radiation boundary condition, is applied to study storm surges and tides on the North Queensland coast. The numerical simulations show that with the tides included in the storm surge model the sea level elevation is generally lower than if we simply add the astronomical tides to the surge. This has been previously observed and has been commonly explained as a nonlinear interaction between the storm surge and the tides. The authors demonstrate that this effect is due to the quadratic bottom friction law. Analysis of the important dynamical processes yields a simple rule to estimate the total sea level due to the combined effects of a storm surge and tide.

Full access