We show that gyrotactic motility within a steady vortical flow leads to tightly clustered aggregations of microorganisms. Two dimensionless numbers, characterizing the relative swimming speed and stability against overturning by vorticity, govern the coupling between motility and flow. Exploration of parameter space reveals a striking array of patchiness regimes. Aggregations are found to form ...

Data storage issues pose a potential problem in the performance and analysis of turbulence simulations. Current practice is to frequently output data from the simulation scaled to 8 bits for use in visualizations. Less frequently, data is output from the simulation in a floating point format (typically single precision) which is capable of capturing the accuracy of the simulation for the purpos...

Using the Goddard Laboratory for Atmospheres Goddard Earth Observing System 5-yr analyses and the Zwack–Okossi equation as the diagnostic tool, the horizontal distribution of the dynamic and thermodynamic forcing processes contributing to the maintenance of a Northern Hemisphere midlatitude blocking anticyclone that occurred during the summer season were examined. During the development of this...

Hurricane and tropical storm statistics verify the modulation of eastern Pacific tropical systems by the Madden– Julian oscillation (MJO) as hypothesized by Maloney and Hartmann. Over twice as many named tropical systems (hurricanes and tropical storms) accompany equatorial 850-mb westerly anomalies than accompany equatorial easterly anomalies, and the systems that do exist are stronger. Hurric...

J. R. Ristorcelli X Division, Los Alamos National Laboratory University of California, Los Alamos, NM 87545 A.C. Poje Division of Applied Mathematics Brown University, Providence, RI 02192 Abstract The e ects of Rossby wave { turbulence interactions on particle dispersion are investigated in a Lagrangian analysis of the potential vorticity equation. The analysis produces several exact statistic...

Superfluid turbulence is governed by two dimensionless parameters. One of them is the intrinsic parameter q which characterizes the relative value of the friction force acting on a vortex with respect to the non-dissipative forces. The inverse parameter q−1 plays the same role as the Reynolds number Re = UR/ν in classical hydrodynamics. It marks the transition between the ”laminar” and turbulen...

The statistics of magnetosphere–ionosphere (MI) coupling derived from a two-month long run of the Lyon–Fedder–Mobarry (LFM) global simulation model are investigated. MI coupling characteristics such as polar cap potential and field-aligned current (FAC), downward Poynting flux and vorticity of ionospheric convection are compared with observed statistical averages and with results from the Weime...

An exact complex mapping is used to show the close relationship between the Schroedinger equation for a charged particle in an external ̄eld, the Landau-Ginsburg equation for the order parameter in a superconductor, and the equation for the evolution of vorticity in a Navier-Stokes compressible, viscous, °uid. The absolute square of the wave function, or complex order paramter, is exactly equal...

The first global climatology of monsoon low-pressure systems is presented here, based on the ERA-Interim reanalysis. Low-pressure systems are classified into three intensity categories and particular focus is given to systems in the category corresponding to a traditional definition of monsoon depressions. Vortex tracks are identified using an automated algorithm applied to the distributions of...

This study uses a shallow-water, normal-mode spectral model to examine the non-linear potential vorticity (PV) dynamics of the break¬down of both infinite an finite-length initial vorticity strips, simulating the inter-tropical convergence zone (ITCZ) found near the tropical eastern Pacific region. Irregularities in convection and diabatic heating are simulated using uniformly and randomly spac...