Studies in upper atmospheric dynamics.
Upper atmospheric dynamics, considering day-night density and pressure variation, wind structure, gravity waves, etc
ATMOSPHERIC PRESSURE↗
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Upper atmosphere dynamics
Upper atmosphere dynamics and model based on equations of mass, momentum, and energy
Friedman, M. P.↗
Some recent atmospheric dynamics research at MSFC
Atmospheric dynamics, and statistical description of turbulence
TURBULENCE↗
Current Scientific Issues in Large Scale Atmospheric Dynamics
Topics in large scale atmospheric dynamics are discussed. Aspects of atmospheric blocking, the influence of transient baroclinic eddies on planetary-scale waves, cyclogenesis, the effects of orography on planetary scale flow, small scale frontal structure, and simulations of gravity waves in frontal zones are discussed.
Miller, T. L.↗
Atmospheric Dynamics of Uranus and Neptune: Theoretical Considerations
The atmospheric dynamics of neptune and uranus are investigated. Uranus, because of its pole on orientation and low internal heat source, is in a dynamically different atmospheric regime from Jupiter and Saturn. Neptune resembles Jupiter and Saturn in orientation and internal heating, but its extremely long radiative time constant puts Neptune in a different class. Voyager observations of seasonal temperature gradients, equator to pole temperature gradients, infrared emission, Bond albedo, possible cloud structures (bands, spots, eddies), and cloud motions can be used to improve the ability to classify planetary atmospheres according to their dynamical regimes.
Andrew P Ingersoll↗
Atmospheric dynamics on Venus and Mars
In this paper, recent information concerning the atmospheric dynamics of Venus and Mars is discussed. In the Venusian atmosphere, the Vega balloon results disclosed the presence of major vertical motions at the 53 km level and demonstrated the near zonality of the atmospheric circulation below the level of the clouds. Pioneer Orbiter observations indicated a continued vortex organization of the cloud level atmosphere in either hemisphere, centered over respective poles. In the case of the Martian atmospheric circulation, the observations are scant. Viking lander data and orbit images have been used to derive cloud motions and compare the measured winds with the predictions for surface conditions from general circulation models.
Limaye, Sanjay Shridhar↗
A normal-mode approach to Jovian atmospheric dynamic
A nonlinear, quasi-geostrophic, baroclinic model of Jovian atmospheric dynamics is proposed, in which vertical variations of velocity are represented by a truncated sum over a complete set of orthogonal functions obtained by a separation of variables of the linearized quasi-geostrophic potential vorticity equation. A set of equations for the time variation of the mode amplitudes in the nonlinear case is then derived. It is shown that, for a planet with a neutrally stable, fluid interior instead of a solid lower boundary, the barotropic mode represents motions in the interior, and is not affected by the baroclinic modes. One consequence of this is that a normal-mode model with one baroclinic mode is dynamically equivalent to a one-layer model with solid lower topography. It is also shown that, for motions in Jupiter's cloudy lower troposphere, the stratosphere behaves nearly as a rigid lid, so that the normal-mode is applicable to Jupiter. The accuracy of the normal-mode model for Jupiter is tested using the following simple problems: (1) forced, vertically propagating Rossby waves, using two and three baroclinic modes, and (2) baroclinic instability, using two baroclinic modes. It is found that the normal-mode model provides qualitatively correct results, even with only a very limited number of vertical degrees of freedom.
Achterberg, Richard K.↗
Parameterization of IR cooling in a middle atmosphere dynamics model. I - Effects on the zonally averaged circulation
A computationally efficient two-stream parameterization of IR cooling is developed for a middle atmosphere dynamics model. The parameterization combines the monochromatic feature of an emissivity formulation with the computational simplicity of a single spatial integral to evaluate the monochromatic transfer equation. Calculations show strong radiative control of the mesopause region and the need for substantial deceleration of the mean zonal winds. Calculated temperatures show good agreement in the summer hemisphere where planetary wave activity is negligible, but in the polar night of the winter hemisphere they are about 30 K too cold, which suggests planetary wave heating must make up the deficit. With observed ozone densities, globally averaged radiative equilibrium temperatures in the 65-75 km region are too cold and an additional heat source about 1 K/day is required.
Apruzese, J. P.↗
Atmosphere dynamic processes structure at 80-105 km altitude
Determination of wind velocity by means of Doppler meteor radars is based on the assumption that an ionized meteor trail drifts together with the neutral atmosphere. From the Doppler frequency shift it is possible to estimate the radial velocity of the trail drift. Conversion of the recorded radial velocity to the true wind velocity vector in the given space region depends both on the radar technical parameters and the chosen atmospheric motion model. The atmospheric dynamic processes structure is considered.
Kalchenko, B. V.↗
Geomagnetic Disturbances Caused by Internal Atmospheric Dynamics
It is commonly believed that geomagnetic disturbances are caused by external influences connected with the solar wind. The 27-day recurrence of perturbations seems to be a strong hint for this interaction. But frequently geomagnetic disturbances occur without any relation to sunspot numbers or radiowave fluxes. This was one of the reasons for introducing hypothetical M-regions on the Sun and their relation to solar wind activities. Only one half of the variance of the geomagnetic AL-index could be related to the solar wind. Therefore it is concluded that internal processes of the magnetosphere were responsible for additional geomagnetic activity. Arguments, which might lead to the suggestion of geomagnetic disturbances as being caused by internal atmospheric dynamics are discussed and a rather preliminary scenario of those processes is proposed.
Sonneman, G.↗
Solar atmospheric dynamics. II - Nonlinear models of the photospheric and chromospheric oscillations
The one-dimensional, nonlinear dynamics of the solar atmosphere is investigated, and models of the observed photospheric (300 s) and chromospheric (200 s) oscillations are described. These are resonances of acoustic wave cavities formed by the variation of the temperature and ionization between the subphotospheric, hydrogen convection zone and the chromosphere-corona transition region. The dependence of the oscillations upon the excitation and boundary conditions leads to the conclusion that for the observed amplitudes, the modes are independently excited and, as trapped modes, transport little if any mechanical flux. In the upper photosphere and lower chromosphere, where the two modes have comparable energy density, interference between them leads to apparent vertical phase delays which might be interpreted as evidence of an energy flux.
Leibacher, J.↗
The Vega balloons - A tool for studying atmosphere dynamics on Venus
The Vega balloon experiment, designed to measure the dynamics of the Venus atmosphere, comprised the balloons themselves, their gondolas with on-board sensors and radio transmitters, and the radio telescope network on the earth. The structures and the physical parameters of the balloon probe are described, together with the instruments on the gondola, designed for the measurements of the atmospheric pressure, temperature, and vertical wind flows, and illumination, as well as possible flashes of lightning. Consideration is also given to the formatting of the information flow for the individual parameters measured.
Kremnev, R. S.↗
Subtropical middle atmosphere dynamics observed by the Chung Li radar
The Chung Li Radar (24.91 N; 121.24 E) has been operating since 1986. A five beam observational configuration was used on a regular basis to study the various dynamics processes in the atmosphere-lower stratosphere height region. Due to its geographical location, the annual Typhoon and Mei-Yu seasons provide good opportunities to study the various interesting dynamic processes such as instabilities, generation of gravity waves, wave mean field interaction, etc. Three dimensional air motions due to these fronts are presented. Special cases of gravity wave generation, propagation and their effects on the turbulent layers are discussed.
Fu, I. J.↗
Atmospheric dynamics
The paper presents an overview of U.S. contributions in the period of 1983-1986, to the analysis and study of the atmosphere's motion and of the role of this motion in the thermodynamics and chemistry of the atmosphere. Special attention is given to the linear and quasi-linear studies of the dynamics of atmospheric disturbances; studies of the wave breaking phenomenon; and investigations of various long-lived features, ranging from climatological stationary waves to long-period oscillations in the tropics. Consideration is also given to diagnostics for the interactions among disturbances and the mean flow, nontraditional approaches to instability and disturbance growth, and dynamical systems and multiple equilibria.
Lindzen, Richard S.↗
Some properties of upper atmosphere dynamics
A unifying description is provided of some important dynamic properties of the upper atmosphere in composition and temperature characteristic of a variety of phenomena, including diurnal and seasonal tides, magnetic storms, and momentum coupling with the magnetosphere. A theoretical multiconstituent model is used which can link the large-scale variations of composition and temperature to the dynamics and energetics of the thermosphere. Global mean properties of the thermosphere are reviewed, and an attempt is made to convey some understanding of the dynamic properties of energy and diffusive mass transport in the thermosphere. Attention is given to sources of energy for the thermosphere, the transport processes involved in the solar diurnal tide of the thermosphere, energy and particle sources for the annual tide, feedback from composition changes to wind-field and temperature variations, energy deposition in the thermosphere during magnetic storms and substorms, and momentum source signatures in the thermosphere.
Mayr, H. G.↗
Theoretical and experimental investigations of upper atmosphere dynamics
A brief overview of the significant contributions made to the understanding of the dynamics of the Earth's upper atmosphere is presented, including the addition of winds and diffusion to the semi-empirical Global Reference Atmospheric Model developed for the design phase of the Space Shuttle, reviews of turbulence in the lower thermosphere, the dynamics of the equatorial mesopause, stratospheric warming effects on mesopause level dynamics, and the relevance of these studies to the proposed Middle Atmosphere Program (1982-85). A chronological bibliography, with abstracts of all papers published, is also included.
Roper, R. G.↗
Future possibilities in objective analysis and data assimilation for atmospheric dynamics
The role that dynamics plays in estimating the state of the atmosphere from incomplete and noisy data is reviewed. Objective analysis represents an attempt at relying mostly on the data and minimizing the role of dynamics in the estimation. Data assimilation tries to balance properly the roles of dynamical and observational information. Sequential estimation is presented as the proper framework for understanding this balance, and the Kalman filter as the ideal, optimal procedure for data assimilation. The optimal filter computes forecast error covariances of a given atmospheric model exactly, and hence data assimilation should be closely connected with predictability studies. This connection is described, and consequences drawn for currently active areas of the atmospheric and related sciences, namely, mesoscale meteorology, long range forecasting, and upper ocean dynamics. Possibilities offered by judicious data assimilation in understanding barotropic adjustment, a phenomenon that appears to play a crucial role in atmospheric behavior on the scale of weeks to months, and hence in long range forecasting are addressed.
Ghil, M.↗
Atmosphere dynamics in the equatorial meteor zone
The study of the atmospheric circulation of the Earth from its surface to the altitudes of 100 to 110 km is essential for establishing atmospheric motion regularities with a view toward perfecting weather forecasting. The main results of the Soviet equatorial meteor expedition (SEME) are presented. A continuous cycle of measurements was carried out. Considerable interdiurnal variation of the zonal component was observed. Importantly, in the meridional component, the prevalence of a two day component was established in the equatorial meteor zone for the first time. The pronounced westward motion of the atmosphere over the equator is noted. The SEME data analysis has shown that the meteor zone is characterized by flashes of intensity of the internal gravity waves and turbulence at highest instability moments of atmosphere due to tidal motion.
Kascheev, B. L.↗