Showing papers on "Atmospheric wave published in 1973"
TL;DR: In this article, an analogy between the supersonic motion of the Moon's shadow and the Earth's terminator is drawn, and it is shown that the terminator may generate gravity waves in this region.
Abstract: Chimonas and Hines1 have pointed out that the Moon's shadow on the Earth's atmosphere during a solar eclipse constitutes a cooling region travelling at supersonic speeds, and may generate atmospheric gravity waves with periods from a couple of minutes up to twelve hours. Atmospheric wave generation by solar eclipses has been observed2–4, though within the source region (the region of total or partial eclipse) the gravity waves have substantially shorter period than outside it. Here I draw an analogy between the supersonic motion of the Moon's shadow and the supersonic motion of the Earth's terminator. The terminator is supersonic between ± 45° latitudes at all altitudes below 100 km and may therefore generate gravity waves in this region.
58 citations
TL;DR: In this article, the effect of internal atmospheric gravity waves upon columnar electron content was studied using a model consisting of plane internal gravity waves propagating in a viscous atmosphere composed of a number of isothermal layers.
53 citations
TL;DR: In this paper, it has been suggested that during a solar eclipse, gravity waves are generated by the Moon's shadow moving with supersonic speed through the Earth's atmosphere1,2.
Abstract: IT has been suggested that, during a solar eclipse, gravity waves are generated by the Moon's shadow moving with supersonic speed through the Earth's atmosphere1,2. After the eclipse of March 7, 1970, several investigators3–6 detected atmospheric gravity waves in the form of travelling ionospheric disturbances (TIDs) using different observational techniques. But it was not possible to decide definitely whether the TIDs were due to the eclipse or to any other sources.
36 citations
TL;DR: In this article, the irreversible heat input generated by atmospheric gravity waves at thermospheric heights and the corresponding temperature increase of the neutral gas were investigated and the results strongly supported the suggestion that geomagnetic activity effect on the exospheric temperature is caused by gravity waves which are generated in the auroral regions.
31 citations
TL;DR: The solar atmosphere is heated by a flux of mechanical waves propagating in one or more of the modes: acoustic, Alfven and gravitational as discussed by the authors, which is known as the solar magnetic field.
Abstract: The solar atmosphere is heated by a flux of mechanical waves propagating in one or more of the modes: acoustic, Alfven and gravitational.
28 citations
TL;DR: The mutual coherence function (MCF) of the complex amplitude of stellar light waves perturbed by atmospheric turbulence has been determined interferometrically as discussed by the authors, in good agreement with horizontal laser-beam determinations.
Abstract: The mutual coherence function (MCF) of the complex amplitude of stellar light waves perturbed by atmospheric turbulence has been determined interferometrically. Results are in good agreement with horizontal laser-beam determinations. Stellar measurements provide quantitative estimations of seeing conditions for astronomical observations.
28 citations
TL;DR: In this article, it is argued that the multiple layers are caused by dynamic instability resulting from reduction in the Richardson number due to wave induced shear and to some background wind shear when the amplitudeto-wavelength ratio grows during propagation into thermally stable height regions of the atmosphere.
Abstract: An FM/CW radar sounding system designed and built by one of us (Richter, 1969) reveals atmospheric wave structure in unparalleled detail. The most outstanding features evident in the record are; internal gravity waves; features resembling Kelvin/Helmholtz instability structures; and multiple layering, often with lamina only a few meters thick. This paper shows a variety of atmospheric structural patterns and compares them with several hypothetical models of internal waves to obtain more insight into the atmospheric processes at work. Special attention is given to the distribution of the Richardson number in trapped and untrapped gravity waves. It is proposed that the multiple layers result from untrapped internal gravity waves whose propagation vector is directed nearly vertically within very stable height regions. It is argued that the layers are caused by dynamic instability resulting from reduction in the Richardson number due to wave induced shear and to some background wind shear when the amplitude-to-wavelength ratio grows during propagation into thermally stable height regions of the atmosphere.
22 citations
TL;DR: In this article, the diurnal oscillation of the atmospheric boundary layer is identified as an important source of mesoscale internal gravity waves in the lower atmosphere, and the oscillation period of these waves is a function of latitude.
Abstract: We can identify the diurnal oscillation of the atmospheric boundary layer as an important source of mesoscale internal gravity waves in the lower atmosphere The oscillation period of these waves is a function of latitude A definitive two-day period may be found in the equatorial regions with scales on the order of a few hundred kilometers In particular, for a situation in which the mean stratification at any time of the day is unstable, the wavelength could he on the order of 100 km This result suggests that some cloud clusters may be originated by this process
19 citations
TL;DR: In this paper, a resonant trio of acoustic gravity waves with nonzero frequencies was found in situations in which viscous damping has to be taken into account, and it was shown that the resonant wave can be found in a situation in which the dampness is not considered.
Abstract: Resonance conditions concerning the nonlinear interaction of acoustic gravity waves are considered. It is shown that a resonant trio of waves with nonzero frequencies can be found in situations in which viscous damping has to be taken into account.
11 citations
TL;DR: In this article, the authors considered the high-frequency waves observed in the solar wind upstream from the earth's bow shock and concluded that explanation of significant magnetic components in terms of directly generated beam waves is untenable, and that sufficient transformation to explain the observations is possible if the electric field of the plasma waves is in the 25mv/m range or higher so that the plasma wave amplify the radiation initially present.
Abstract: Interpretations of the high-frequency waves observed in the solar wind upstream from the earth's bow shock are considered, and it is concluded that explanation of significant magnetic components in terms of directly generated beam waves is untenable Transformation of beam-generated electron plasma waves into radiation is analyzed Sufficient transformation to explain the observations is possible if the electric field of the plasma waves is in the 25-mv/m range or higher so that the plasma waves amplify the radiation initially present Such amplification leads to very directive radiation along the longest ray paths through the amplification or source region This interpretation provides an explanation for the variable ratio of energy density in the electric field to that in the magnetic field Namely, when these energy densities are low and comparable, we are observing almost pure highly directive electromagnetic radiation which either has decreased in amplitude in traveling from the amplification region or was produced in a small amplification region When the energy density in the electric field is high and considerably larger than the magnetic energy density, the spacecraft is in an amplification region and sampling both radiation and plasma waves
01 Jan 1973
TL;DR: In this paper, the authors investigated the nonlinear interaction near the center of maximum mean motion of a jet stream and found that interactions of waves of low frequencies and those between the mean zonal motion and low frequency waves contribute most to the low frequency range of the energy spectrum of the zonal component of the turbulent motion.
Abstract: An investigation of the nonlinear interaction near the center of maximum mean motion of a jet stream indicates that interactions of waves of low frequencies and those between the mean zonal motion and low frequency waves contribute most to the low frequency range of the energy spectrum of the zonal component of the turbulent motion, whereas the effects of the sphericity and Reynolds stresses contribute most to the low frequency range of the spectra of the meridional turbulent motion. In ranges of intermediate and high frequencies, the interactions between the mean zonal motion and waves of frequency range in question contribute most to the respective spectra. In the investigation of the spectral structure of atmospheric waves near a jet stream, it is found that in the region of the maximum zonal mean motion the kinetic energy of the zonal and meridional components of the turbulent motion is generally contributed by the nonlinear interactions between waves of various frequencies with the mean zonal motion. It is also found that as waves travel eastward from the center of maximum mean zonal motion, the velocity-amplitudes of waves of low frequencies grow at the expense of the kinetic energy of waves of higher frequencies. This suggests that center maximum mean motion of the jet stream tends to excite wave motion of high frequencies, and that the kinetic energy of these waves is transferred to waves of lower frequencies through nonlinear interactions. DOI: 10.1111/j.2153-3490.1973.tb01600.x
01 Jan 1973
TL;DR: In this article, the potential significance of atmospheric waves as contributors to the diurnal heat budget of the thermosphere is recalled and discussed in the context provided by the work of Chandra and Sinha.
01 Jan 1973
TL;DR: In this article, traveling internal gravity waves, like the lee waves referred to by Lilly, can have a significant effect in the vertical transfer of kinetic energy and momentum from the westerly flow.
Abstract: We propose that traveling internal gravity waves, like the lee waves referred to by Lilly, can have a significant effect in the vertical transfer of kinetic energy and momentum from the westerly flow. A program to study the effect is described here.
01 Jan 1973
TL;DR: In this paper, the spatial spectral density of the index of refraction was estimated in the case of a locally homogeneous and isotropic random field with the knowledge of the temporal correlation function of amplitude fluctuations on the laser beam axis.
Abstract: It is shown that in the case of a homogeneous and isotropic turbulence the knowledge of the temporal correlation function of the amplitude fluctuations on the laser beam axis allows the estimation of the spatial spectral density of the index of refraction. Under certain conditions this method may be used for atmospheric turbulent flow also, which represents in general a locally homogeneous and isotropic random field.
01 Apr 1973
TL;DR: In this paper, internal waves in an atmospheric jet stream are discussed, using both linear and non-linear theory, and it is shown that the wave phase-speeds depend only on the total static stability in the jet stream layer.
Abstract: Internal waves in an atmospheric jet stream are discussed, using both linear and non-linear theory. In the former case., the wave phase-speeds depend only on the total static stability in the jet stream layer. In the latter case, the temperature profile curvature plays the main role in the behaviour of gravity-type waves.
Journal Article•
01 Oct 1973