Degenerate optical parametric oscillators can exhibit both uniformly translating fronts and nonuniformly translating envelope fronts under the walk-off effect. The nonlinear dynamics near threshold is shown to be described by a real convective Swift-Hohenberg equation, which provides the main characteristics of the walk-off effect on pattern selection. The predictions of the selected wave vecto...

In this special technical report we present fundamental studies on instability analysis. When an electromagnetic wave linearly interacts with an active medium or system, there can occur basically two types of instabilities. One of them, in which the wave grows indefinitely with tin», Is called absolute Instability, and the other, in which the wave grows spatially as it travels, is called convec...

[1] Convective mixing in the fluid outer core can induce rapid transient decrease of the geomagnetic dipole. Here we determine rates of dipole moment decrease as a function of magnetic Reynolds number following convective instability in a numerical dynamo and in axisymmetric kinematic flows. Our calculations show that mixing flows induce reversed magnetic flux on the core-mantle boundary throug...

The diurnal cycle of the North American monsoon is analyzed based on the output from a mesoscale model simulation. Statistically significant diurnal cycle in precipitation is identified, with heavy precipitation—essentially convective—dominating in local afternoons. Temporal evolution of key parameters in relation to precipitation is investigated, based on which a sequence of the dynamic/thermo...

Spatial development of turbulence is studied with the unidirectionally coupled logistic lattice model. Transition from absolute to convective instability is described. A numerical method, allowing one to compute convectively unstable states without numerical artifacts is introduced and used for construction of the phase diagram. Innuence of external noise on the convectively unstable regimes is...

The physics of thermomechanical coupling of the continental lithosphere and its surrounding mantle is studied using a simple hydrodynamic model in which a fluid is heated from below and is bounded by rigid side walls. Rayleigh numbers up to 10 are considered. A series of finite-element stability analyses is employed to characterize systematically the nature of convective instability in such a s...

Conditions leading to convective outbreak in the Tropics are investigated by multivariate analysis of sounding and satellite data from the tropical western Pacific area. Circumstances which make the prediction problem difficult are discussed, and addressed by applying linear “error-in-variables” and nonlinear statistical simulation techniques to a large dataset. Lowto mid-tropospheric moisture ...

We use hydrodynamic simulations with adaptive grid refinement to study the dependence of hot gas flows in X-ray luminous giant elliptical galaxies on the efficiency of heat supply to the gas. We consider a number of potential heating mechanisms including Type Ia supernovae and sporadic nuclear activity of a central supermassive black hole. As a starting point for this research we use an equilib...

Recent observational analysis reveals the central role of three multicloud types, congestus, stratiform, and deep convective cumulus clouds, in the dynamics of large-scale convectively coupled Kelvin waves, westward-propagating two-day waves, and the Madden–Julian oscillation. A systematic model convective parameterization highlighting the dynamic role of the three cloud types is developed here...

Based on an extended model of Marangoni convection during absorption accompanied by chemical reaction certain characteristics of the process are studied. Thus, the probability of oscillatory modes occurring in the system is analysed, the dimensions of the convective cells are evaluated and the gas-liquid contact time necessary for the instability to appear is determined. The quantitative conclu...