Six sets of particle image velocimetry (PIV) data from the bottom boundary layer of the coastal ocean are examined. The data represent periods when the mean currents are higher, of the same order, and much weaker than the wave-induced motions. The Reynolds numbers based on the Taylor microscale (Re ) are 300–440 for the high, 68–83 for the moderate, and 14–37 for the weak mean currents. The mod...

We determine subsidence in the Arctic stratospheric vortex from measurements of the column density of hydrogen fluoride, using a rotational line in thermal emission. The data were obtained with the far-infrared spectrometer on board the NASA DC-8 aircraft during the Arctic Airborne Stratospheric Expedition, from January through March 1992. A wide range of meteorological conditions was sampled, ...

Substantial bottom topography in a basin with planetary vorticity gradients strongly affects the vertical structure of the linear topographic and planetary Rossby waves that spin up the ocean circulation. There is no barotropic mode with large amplitude topography and stratification. It is shown that the lowest frequency two-layer quasigeostrophic waves that exist with stratification, planetary...

Singular vectors (SVs) have been applied to cyclogenesis, to initializing ensemble forecasts, and in predictability studies. Ideally, the calculation of the SVs would employ the analysis error covariance norm at the initial time or, in the case of cyclogenesis, a norm based on the statistics of initial perturbations, but the energy norm is often used as a more practical substitute. To illustrat...

Low-level mesovortices are associated with enhanced surface wind gusts and high-end wind damage in quasi-linear thunderstorms. Although damage associated with mesovortices can approach that of moderately strong tornadoes, skill in forecasting mesovortices is low. The overarching goal of this work is to understand mesovortices and how they develop, to improve the skill in forecasting them. This ...

The nonlinear Schrödinger (NLS) equation describing the propagation of weakly rotational wave packets in an infinitely deep fluid in Lagrangian coordinates has been derived. The vorticity is assumed to be an arbitrary function of Lagrangian coordinates and quadratic in the small parameter proportional to the wave steepness. The vorticity effects manifest themselves in a shift of the wave number...

Holographic PIV is used to measure the three-dimensional velocity distribution of fully developed turbulent flow within a square duct at ReH = 1.2 × 10. The data is used for mapping the structure of the filtered, three-dimensional vorticity, strain-rate and subgrid-scale (SGS) stress tensor distributions. Visualizations of iso-vorticity surfaces show structures that are only slightly elongated,...

Rivers empty into oceans and lakes as turbulent sediment-laden jets, which can be characterized by a Gaussian horizontal velocity profile that spreads and decays downstream because of shearing and lateral mixing at the jet margins. Recent experiments demonstrate that this velocity field controls river-mouth sedimentation patterns. In nature, diffuse jets are associated with mouth bar deposition...