A study of the formation and movement of sequential Sporadic-E layers observed during the nighttime hours at two Indian low-latitude stations, SHAR (dip 10°N) and Waltair (dip 20°N) shows that the layer are formed around 19:00 h. IST at altitudes of ~180 km. They descend to the normal E-region altitude of about 100 km in three to four hours and becomes blanketing type of Es before they disappea...

Estimates of the effective wind speed disturbances acting on a turbine are useful in a variety of control applications. A Kalman filter-based wind speed estimator is presented here for estimation of the effective hub-height wind speed as well as linear horizontal and vertical shear components. The wind speed estimator is evaluated using an aeroelastic simulator with the National Renewable Energ...

Aiming at the non-stationary and stall flutter problems of wind turbine blade caused by transient load fluctuations, the dynamic properties of wind turbine were studied, the blade was simplify to a cantilever beam in case of the action of shear deformation and cross section rotating effect were considered in this analysis, equations of the blade were established based on D'Alemberts' principle ...

Pilot reports from special turbulence-reporting periods were used t o investigate methods of analyzing and forecasting clear-air turbulence over the United States. Meteorological analyses for the special reporting periods were made objectively by computer using only standard upper air rawinsonde measurements. The wind analyses were built upward from the 400-mb level to the 200-mb level using th...

Ducted gravity waves are associated with potentially large perturbations in horizontal winds. It may be shown, neglecting friction, that these perturbations are maximized at the surface and minimized at the top of the wave duct, producing perturbation vertical wind shear as well. The magnitude of this shear is maximized in the wave ridge and the wave trough. The perturbation shear may be signif...

In this paper we examine the dynamics of unstable critical layers in stratified shear flows. This is done from the framework of the wave interaction theory of shear instabilities, which views instability as arising from the mutual interaction between wave motions that are present in the background shear and density fields. By formulating a simple analytical model of the structure of vorticity w...

The first theory of wind-driven flow is that of Ekman, who assumed a uniform eddy viscosity and derived the velocity spiral that bears his name. Over the years, observations of wind stress and current have improved to the point that frictional momentum transfer in the upper ocean can be quantified. Observations of velocity spirals are reviewed to address such issues as the vertical structure an...

The aim of this paper is to contribute to the understanding of and to model the processes controlling the amplitude of the wind of Rayleigh-Bénard convection. We analyze results from direct simulation of an L/H=4 aspect-ratio domain with periodic sidewalls at Ra=(10(5), 10(6), 10(7), 10(8)) and at Pr=1 by decomposing independent realizations into wind and fluctuations. It is shown that, deep in...

An hierarchy of ocean models is used to investigate the dynamics of the eastward surface jets that develop along the Indian Ocean equator during the spring and fall, the Wyrtki jets (WJs). The models vary in dynamical complexity from 21⁄2-layer to 41⁄2-layer systems, the latter including active thermodynamics, mixed layer physics, and salinity. To help identify processes, both linear and nonlin...