Passive scalar transport in a spatially-extended background of roll convection is considered in the time-periodic regime. The latter arises due to the even oscillatory instability of the cell lateral boundary, here accounted for by sinusoidal oscillations of frequency ω. By varying the latter parameter, the strength of anticorrelated regions of the velocity field can be controled and the condit...

Results from the 1995 season of site-testing experiments at the South Pole are presented, in which the seeing was measured using balloon-borne microthermal probes. Our analysis shows a marked division of the atmosphere into two characteristic regions: (i) a highly turbulent boundary layer (0–220 m) associated with a strong temperature inversion and wind shear, and (ii) a very stable free atmosp...

The Arctic is a region in the northernmost hemisphere of the Earth. It is known for its extreme environmental conditions, in particular its cold temperatures, high winds, snow, and ice. Yet, life in this polar region is plentiful and includes both terrestrial and marine organisms. The Arctic Ocean provides for a unique, cold-temperatureadapted ecosystem containing plankton, marine mammals, and ...

Phytoplankton patchiness ubiquitously observed in marine ecosystems is a simple physical phenomenon. Only two factors are required for its formation: one is persistent variations of inhomogeneous distributions in the phytoplankton population and the other is turbulent stirring by eddies. It is not necessary to assume continuous oscillations such as limit cycles for realization of the first fact...

This paper presents a time domain analysis framework for predicting nonlinear response of long-span bridges under turbulent winds. The nonlinear unsteady aerodynamic forces are modeled based on static force coefficients, flutter derivatives, admittance functions, and their spanwise correlations at varying angles of incidence. This analysis framework incorporates frequency dependent parameters o...

Some features of bridge aerodynamics of wind engineering are reviewed at this time, in view of the collapse of the Tacoma Narrows Bridge and also to celebrate Professor Alan G. Davenport’s 40 years of contribution to the field. Primary highlighted topics are: description of motion-dependent forces for flutter instability, presentation of gust responses caused by turbulent winds and suppression ...