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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Full Vorticity Budget of the Arabian Sea from a 0.1° Ocean Model: Sverdrup Dynamics, Rossby Waves, and Nonlinear Eddy Effects

Abstract The Arabian Sea, influenced by the Indian monsoon, has many unique features, including its basin-scale seasonally reversing surface circulation and the Great Whirl, a seasonal anticyclonic system appearing during the southwest monsoon close to the western boundary. To establish a comprehensive dynamical picture of the Arabian Sea, we utilize numerical model output and design a full vorticity budget that includes a fully decomposed nonlinear term. The ocean general circulation model has 0.1° resolution and is mesoscale eddy-resolving in the region. In the western boundary current system, we highlight the role of nonlinear eddies in the life cycle of the Great Whirl. The nonlinear eddy term is of leading-order importance in this feature’s vorticity balance. Specifically, it contributes to the Great Whirl’s persistence in boreal fall after the weakening of the southwesterly winds. In the open ocean, Sverdrup dynamics and annual Rossby waves are found to dominate the vorticity balance; the latter is considered as a key factor in the formation of the Great Whirl and the seasonal reversal of the western boundary current. In addition, we discuss different forms of vertically integrated vorticity equations in the model and argue that the bottom pressure torque term can be interpreted analogously as friction in the western boundary and vortex stretching in the open ocean.

58 GEOSCIENCES↗
NASA NTRS1993

Global normal-mode Rossby waves observed in stratospheric ozone data

Westward-propagating Rossby normal-mode planetary waves are documented in stratospheric ozone data using Solar Backscatter Ultraviolet (SBUV) satellite measurements. These modes are evidenced by enhanced spectral power and near-global coherence for westward-traveling zonal wave 1 oscillations with periods of 5-10 days. The ozone waves have maxima in high latitudes of the middle stratosphere (due to transport) and over midlatitudes in the upper stratosphere (due to photochemistry). These modes are nearly continuous throughout the eight years of SBUV observations, with maximum global coherence during the equinoxes. The upper-stratospheric waves are symmetric (in phase) between hemispheres, even for modes previously identified as antisymmetric in geopotential height. This behavior is due to differing wave vertical structure in each hemisphere; the planetary temperature waves are nearly in phase in the upper stratosphere, even though the height waves are out of phase. The observed ozone waves are furthermore compared to calculations based on linear wave transport and photochemistry, incorporating derived wind and temperature fields. Good agreement is found, showing that normal modes provide an idealized context to study the linear wave behavior of trace constituents in the real atmosphere.

Randel, William J.↗
NASA NTRS1996

Evidence of Boundary Reflection of Kelvin and First-Mode Rossby Waves

TOPEX/POSEIDON sea level data leads to new opportunities to investigate some theoretical mechanisms suggested to be involved in the El Nino/Southern Oscillation phenomenon in the tropical Pacific ocean. In particular, we are interested in studying the western boundary reflection, a process crucial for the delayed action oscillator theory, by using the TOPEX/POSEIDON data from November 1992 to May 1995.

boundary reflection TOPEX/POSEIDON↗
DOE OSTI2024

The maintenance of coherent vortex topology by Lagrangian chaos in drift-Rossby wave turbulence

Here, this work introduces the “potential vorticity bucket brigade,” a mechanism for explaining the resilience of vortex structures in magnetically confined fusion plasmas and geophysical flows. Drawing parallels with zonal jet formation, we show how inhomogeneous patterns of mixing can reinforce, rather than destroy non-zonal flow structure. We accomplish this through an exact stochastic Lagrangian representation of vorticity transport, together with a near-integrability property, which relates coherent flow topology to fluid relabeling symmetries. We demonstrate these ideas in the context of gradient-driven magnetized plasma turbulence, though the tools we develop here are model-agnostic and applicable beyond the system studied here.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1978

Solitary Rossby waves in zonal shear flows and their interactions

Interactions of long-wave solitons propagating in shear flows are described by a coupled pair of Korteweg-de Vries equations. The basic equation of motion for the analysis is the quasi-geostrophic forecast equation, and the interaction of two wave modes is studied. The solution for mode 1-mode 2 interaction of solitary waves in an asymmetric shear flow of a barotropic atmosphere with divergence is constructed. Streamline patterns for certain flows are obtained. An unsteady solitary wave solution for a modified Korteweg-de Vries equation is derived.

Redekopp, L. G.↗
NASA NTRS1981

Large amplitude stationary Rossby waves in the Southern Hemisphere

Observational evidence of the characteristics of the large amplitude, short wavelength stationary waves found in the lee of South America and Australia during the complete first special observing period of the first GARP global experiment is presented. The structure and evolution of the waves are described and their possible origin discussed.

Kalnay, E.↗
NASA NTRS1983

Large amplitude stationary Rossby waves in the southern hemisphere - Observations and theory

Further observational evidence is presented for the existence of large amplitude short stationary waves during the month of January, 1979 in the lee side of South America. These waves are noted not to have been produced by either topography or CISK; their cause was probably related to stronger tropical convective heating over the Amazon and central Pacific during January. This source of stationary forcing was associated with the weaker easterlies and stronger westerlies in the topics, which allowed free propagation of the energy from the stationary forcing into the extratropics.

Kalnay, E.↗
NASA NTRS1984

Stationary Rossby wave propagation through easterly layers

The zonal mean basic state sensitivity of the steady response to midlatitude mountain forcing is examined through the numerical solution of linearized shallow water equations on a sphere. The zonal mean basic state consists of meridionally varying zonal winds and meridional winds. Attention is given to cases in which the former are westerly everywhere, except within a tropical region in which they are easterly. A zonal wavenumber three mountain confined to the Northern Hemisphere midlatitudes provides the forcing. It is concluded that critical latitude effects on wave propagation are sensitive to mean meridional circulation structure in the critical latitude region of the model.

Schneider, E. K.↗
NASA NTRS1985

Over-reflection of barotropic Rossby wave packet

Interference of stationary and traveling waves of sufficiently large amplitude can cause vacillations in the instantaneous EP-flux and its divergence. Such fluctuations may provide an explanation for some of the vacillations in transport and in the mean flow observed in the stratosphere. While there has been a focus on a simple two-component system, in reality several spectral components are likely to be present. For sufficiently large mean flow deceleration, the local wave field and the quasi-linear description developed here would presumably break down.

Takano, K.↗
NASA NTRS1986

Large-amplitude, short-scale stationary Rossby waves in the Southern Hemisphere - Observations and mechanistic experiments to determine their origin

Further observational evidence of the existence of large-amplitude stationary waves in the Southern Hemisphere during January 1979 is presented. Possible forcing mechanisms for the stationary waves are discussed, and two control experimental forecasts are presented: 15-day integrations with the GLAS Fourth Order GCM, starting from January 5 and Febuary 4, 1979. These forecasts are compared with the GLAS analyses for the same periods, discussing the extent to which the observed January waves are reproduced in the forecast. Several mechanistic experiments are reported in which the Andean orography, tropical heating, regional heating, and initial westerly flow are artificially modified. The effects of these changes on the stationary waves are discussed.

Kalnay, E.↗
NASA NTRS1987

Rossby waves and two-dimensional turbulence in a large-scale zonal jet

Homogeneous barotropic beta-plane turbulence is investigated, taking into account the effects of spatial inhomogeneity in the form of a zonal shear flows. Attention is given to the case of zonal flows that are barotropically stable and of larger scale than the resulting transient eddy field. Numerical simulations reveal that large-scale zonal flows alter the picture of classical beta-plane turbulence. It is found that the disturbance field penetrates to the largest scales of motion, that the larger disturbance scales show a tendency to meridional rather than zonal anisotropy, and that the initial spectral transfer rate away from an isotropic intermediate-scale source is enhanced by the shear-induced transfer associated with straining by the zonal flow.

Shepherd, Theodor G.↗
NASA NTRS1989

Resonant Rossby waves and solar activity

Large scale transient waves are an essential part of atmospheric dynamics. Some of these waves (like 27 day waves) could have a solar nature. The contribution of the 27 day planetary waves to a total long period spectrum of the atmospheric processes during one solar cycle was investigated. Ivanovsky and Krivolutsky proposed that the 27 day wave has a resonant nature. The real atmospheric processes were investigated. The method of 2-D wave analysis used is described by Krivolutsky. It was concluded that the resonant nature of the 27 day wave is not unicum. There are long periods waves (50 day wave) in stratosphere which belong to the resonant waves, too. It is a very interesting fact for the solar activity-weather problem.

Krivolutsky, A. A.↗