Weakly nonlinear stability of regimes of free hydromagnetic thermal convection in a rotating horizontal layer with free electrically conducting boundaries is considered in the Boussinesq approximation. Perturbations are supposed to involve large spatial and temporal scales. Applying methods for homogenisation of parabolic equations, we derive the system of amplitude equations governing the evol...

In a density-stratified turbulent medium, the cross helicity 〈u′ · B′〉 is considered as a result of the interaction of the velocity fluctuations and a large-scale magnetic field. By means of a quasilinear theory and by numerical simulations, we find the cross helicity and the mean vertical magnetic field to be anti-correlated. In the high-conductivity limit the ratio of the helicity and the mea...

Large-scale chaotic stirring stretches tracer contours into filaments containing fine spatial scales until smallscale diffusive processes dissipate tracer variance. Quantification of tracer transport in such circumstances is possible through the use of Nakamura’s ‘‘effective diffusivity’’ diagnostics, which make clear the controlling role of stirring, rather than small-scale dissipation, in lar...

Storm tracks play a major role in regulating the precipitation and hydrological cycle in midlatitudes. The changes in the location and amplitude of the storm tracks in response to global warming will have significant impacts on the poleward transport of heat, momentum and moisture and on the hydrological cycle. Recent studies have indicated a poleward shift of the storm tracks and the midlatitu...

Abstract The origins of the upper limb Atlantic meridional overturning circulation and partition among different routes has been quantified with models at eddy-permitting one eddy-resolving model or low-resolution assimilating observations. Here, a step toward bridging this gap is taken by using Southern Ocean State Estimate (SOSE) 1/6° horizontal resolution to compute Lagrangian diagnostics fr...

The Fisher-Kolmogorov-Petrovskii-Piskunov equation with a variable growth rate and advection by an incompressible velocity field is considered as a model for plankton dispersed by ocean currents. If the average growth rate is negative then the model has a survival-extinction transition; the location of this transition in the parameter space is constrained using variational arguments and delimit...

In this paper we have estimated typical anomalous viscosity, resistivity, and thermal difffusivity of the solar wind plasma. Since the solar wind is collsionless plasma, we have assumed that the dissipation in the solar wind occurs at proton gyro radius through wave-particle interactions. Using this dissipation length-scale and the dissipation rates calculated using MHD turbulence phenomenology...

Radial electron heat transport in a low-collisionality, current-carrying resistive plasma confined in an axisymmetric toroidal magnetic field is hypothesized to be caused by the paleoclassical collisional processes of parallel electron heat conduction and radial magnetic-field diffusion. The electron distribution is Maxwellianized and the electron temperature equilibrated over a long length L t...

[1] Absolute and relative diffusivity are measured on a rip-channeled beach using 30 position-tracking drifters released in clusters (4–12 drifters) deployed on 7 days with different wave forcing and tidal elevations at Sand City, Monterey Bay, California. Diffusivity and dispersion were found to be larger on days with rip current flow patterns and larger waves. Rip currents cause material to d...