Turbulent magnetic fields abound in nature, pervading astrophysical, solar, terrestrial and laboratory plasmas. Understanding the ubiquity of magnetic turbulence and its role in the universe is an outstanding scientific challenge. Here, we report on the transition of magnetic turbulence from an initially electron-driven regime to one dominated by ion-magnetization in a laboratory plasma produce...

Toward elucidating how a wavy porous sand bed perturbs a turbulent flow above its surface, we record pressure within a permeable material resembling the region just below desert ripples, contrasting these delicate measurements with earlier studies on similar impermeable surfaces. We run separate tests in a wind tunnel on two sinusoidal porous ripples with aspect ratio of half crest-to-trough am...

In this second part of a two-part study, details of the upper-ocean response within an idealized baroclinic current to a translating tropical cyclone are examined in a series of nonlinear, reduced-gravity numerical simulations. Based on observations obtained as part of a joint NOAA–National Science Foundation (NSF) experiment in Hurricane Lili (2002), the preexisting ocean mass and momentum fie...

This discussion paper is/has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP if available. Abstract Idealized large-eddy simulations were performed to investigate the impact of different mountain geometries on daytime pollution transport by thermally driven winds. The main objective was to determine interactions bet...

Experiments with the coupled climate model CLIMBER-3a, which contains an oceanic general circulation model, show deep upwelling in the Southern Ocean to be proportional to the surface wind stress in the latitudinal band of Drake Passage. At the same time, the distribution of the Southern Ocean upwelling onto the oceanic basins is controlled by buoyancy distribution; the inflow into each basin b...

Here I discuss the X-ray emission resulting from the interaction of star cluster winds with the surrounding medium. I demonstrate that X-ray emission from the free wind region dominates the total bubble X-ray luminosity if the central star cluster is sufficiently young, massive and compact. I also prove that strong radiative cooling is a crucial ingredient which defines the physical properties ...

We study the acceleration of electrons and positrons at an electromagnetically modified, ultrarelativistic shock in the context of pulsar wind nebulae (PWNe). We simulate the outflow produced by an obliquely rotating pulsar in proximity of its termination shock with a two-fluid code which uses a magnetic shear wave to mimic the properties of the wind. We integrate electron trajectories in the t...

Understanding the situation, behavior and the nature of sand dunes and also their location, transport and deposition are very important. On the other hand, the importance of sand dunes is due to the impacts that they have on water and soil resources, flora and fauna and human infrastructure. This study, looks at the development patterns of sand dunes in Mesr erg region. In the first part, data ...

The overall goal of this research is to improve the accuracy and usefulness of wind retrievals from synthetic aperture radar (SAR) imagery of the sea surface under and near the centers of tropical cyclones (TCs). SAR provides unique high resolution (even sub-km-scale) imagery of the ocean surface roughness underneath TCs. However, the standard methods for interpreting this information in terms ...

Radiative transfer equation in an accretion disk wind is examined analytically and numerically under the plane-parallel approximation in the subrelativistic regime of (v/c), where v is the wind vertical velocity. Emergent intensity is analytically obtained for the case of a large optical depth, where the flow speed and the source function are almost constant. The usual limb-darkening effect, wh...