The authors study the stability of a barotropic sinusoidal meridional flow on a b plane. Because of bottom drag and lateral viscosity, the system is dissipative and forcing maintains a basic-state velocity that carries fluid across the planetary vorticity contours; this is a simple model of forced potential vorticity mixing. When the Reynolds number is slightly above the stability threshold, a ...

Intraseasonal fluctuations of the large scale divergent circulation of the tropical troposphere during the one year period December 1, 1978 November 30, 1979 are examined using analyses prepared by the European Centre for Medium Range Weather Forecasts (ECMWF). It is demonstrated through a number of empirical orthogonal function (EOF) analyses that highly coherent, equatorially symmetric fluctu...

We examine the generation of a magnetic field in a solar-like star and its effects on the internal distribution of the angular velocity. We suggest that the evolution of a rotating star with magnetic fields leads to an equilibrium value of the differential rotation. This equilibrium is determined by the magnetic coupling, which favours a constant rotation profile, and meridional circulation whi...

Accuracies reached in space astrometry now permit the accurate determination of astrometric radial velocities, without any use of spectroscopy. Knowing this true stellar motion, spectral shifts intrinsic to stellar atmospheres can be identified, for instance gravitational redshifts and those caused by velocity fields on stellar surfaces. The astrometric accuracy is independent of any spectral c...

Previous work on the angular momentum balance and meridional circulation of the solar convective zone (SCZ) generally consists either of semianalytic approaches in which a simple turbulence model is adopted, or full direct numerical simulation (DNS) of the hydrodynamics or magnetohydrodynamics (MHD). In both instances the inclusion of magnetic fields has been troublesome. Also, both approaches ...

Probability density functions (pdfs) are employed to evaluate the distribution of velocities in the global ocean. This study computes pdfs of ocean surface velocity using altimetric data from the TOPEX/Poseidon satellite. Results show that the shape of the observed pdfs changes with the size of the domain over which they are calculated: if data are drawn from a small region of the ocean, the pd...

We investigate the influence of large-scale meridional circulation on solar p-modes by quasi-degenerate perturbation theory, as proposed by Lavely and Ritzwoller (1992). As an input flow we use various models of stationary meridional circulation obeying the continuity equation. This flow perturbs the eigenmodes of an equilibrium model of the Sun. We derive the signatures of the meridional circu...

Ring diagram analysis of solar oscillation power spectra obtained from MDI data is carried out to study the velocity fields in the outer part of the solar convection zone. The three dimensional power spectra are fitted to a model which has a Lorentzian profile in frequency and which includes the advection of the wave front by horizontal flows, to obtain the two components of the sub-surface flo...

[1] The spatial and temporal features of the El Niño/ Southern Oscillation (ENSO) meridional scales are investigated using the Hadley Center Global Sea Ice and Sea Surface Temperature (HadISST) data for the period of 1950–2007. The results show that the meridional scales of the ENSO warm and cold events are asymmetric and exhibit interdecadal changes. The meridional extent of the sea surface te...