We consider the shallow water equation and the vorticity equations for a variable height of topography. On the assumptions that the atmosphere is incompressible and a constant density, we simplify the coupled dynamic equations. The change in topographic height is handled as the sum of the inherent and changing topography using the perturbation method, together with appropriate boundary conditio...

Helmholtz’s equations provide the motion of a system of N vortices which describes a planar incompressible fluid. A relative equilibrium is a particular solution of these equations for which the distances between the particles are invariant during the motion. In this article, we are interested in relative equilibria formed of concentric regular polygons of vortices. We show that in the case of ...

A new perturbation analysis is presented which provides a first approximation to the wave-current interaction. The model is shown to provide a good description of laboratory data provided by Swan, Cummins & James (2000) and of results from a numerical formulation. These comparisons confirm that the near-surface vorticity leads to an important modification of the dispersion relation. The results...

[1] The rapid intensification and decay in Hurricane Charley (2004) was sampled by the WSR-88Ds in Key West and Tampa. Charley’s axisymmetric wind fields, vertical vorticity, perturbation pressure, and reflectivity were derived from the ground-based velocity track display (GBVTD) technique. Charley’s rapid intensification was accompanied by a contracting eyewall. The central pressure dropped 33...

Separate vector expressions for the rate of change of direction of the potential temperature gradient vector resulting from the geostrophic vorticity and geostrophic deformation, referred to as QVR and QDR, respectively, are derived. The evolution of the thermal structure and forcing for quasigeostrophic vertical motion in an occluded cyclone are investigated by examining the distributions of Q...

On 20–22 July 2012, a severe rainstorm occurred in the Sichuan basin of Southwest China and Beijing area North China. This was related to activities Tibetan Plateau vortex (TPV) (SWCV). By using radiosonde, satellite brightness temperature, NCEP_FNL data, we investigated helicity characteristics nearly vortexes their effect on convection. Results showed that (1) strong precipitation mainly inte...

The drops are used to control the descents,  stabilize the bed level, and control the upstream water level in sloping channels with less slope than the ground slope. The current study presents a numerical analysis of hydraulic characteristics in the vertical drop using computational fluid dynamics. At first, the laboratory models were used for verification and choosing the best model of turbule...

in this paper, synoptic patterns associated with maximum precipitation over the khorasan region, between 1985-2000 with the computation of some forcing functions are studied and classified into three types. type a: consists of the anticyclones that move from the scandinavian peninsula and central-europe in an east and south-east direction during cold seasons, with relatively high speed and cold...