Wave motions in the atmosphere and related ionospheric phenomena

Murata, Hiroo

doi:10.1007/bf00168068

Cited by 15 publications

(8 citation statements)

References 237 publications

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“…Of particular interest is the role of traveling ionospheric disturbances (TIDs) [Davis andDaRosa, 1969;Davis, 1971;Murata, 1974]. TIDs are traveling waves with periods from 10 min to hours that introduce TEC variations on the order of 1-2% near noon and 3-4% near sunrise [Davis andDaRosa, 1969].…”

Section: Discussionmentioning

confidence: 99%

A statistical characterization of local mid‐latitude total electron content

Gail¹,

Prag²,

Coco³

et al. 1993

J. Geophys. Res.

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The integrated line-of-sight electron density within the ionosphere, known as the total electron content (TEC), is commonly used to quantify ionospheric propagation effects. In order to extrapolate singlepoint measurements of TEC to other locations and times, some characterization of the TEC spatiotemporal variation must be available. Using a four-channel receiver tracking coded signals from the NAVSTAR Global Positioning System satellites, estimates of both the mean variation and correlation coefficient have been made for the approximately 1200-km or 1-hour local time radius ionospheric region within view of a mid-latitude station. Results were obtained for morning and midday over a 4-week period near the autumnal equinox in 1989. The derived mean variation was found to be well characterized by linear functions of lhe local time and latitude separation between the ground site and the ionospheric penetration point of the signal. The correlation coefficient during midday was found to decrease linearly with latitude, longitude, and time separation, with values of about 0.91 for a 1000-km separation and 0.98 for a 1-hour separation. During morning hours the longitude and time coefficients were similar to the middayvalues, but the latitude coefficient was found to have a nonlinear dependence, with values as small as 0.70. The combined results suggest that the decorrelation is due primarily to longer term TEC fluctuations, such as day-to-day variation in the TEC spatial dependence, rather than to transient effects such as traveling ionospheric disturbances. The analysis provides a spatiotemporal characterization of TEC that can be used to extrapolate TEC values from single-point measurements. INTRODUCI•ONThe integrated linc-of-sight electron density within the ionosphere, known as the columnar content or total electron content (TEC), is a fundamental parameter that is often used to quantify ionospheric propagation effects such as signal time delay, Faraday rotation, phase advance, and dispersion. TEC is typically derived from ground-based measurements of either the Faraday rotation angle or the group delay of coded signals transmitted by selected satellites. Such measurements define the TEC value at the time of the measurement along a single path, but the measurements cannot be extrapolated to other times and locations without further information about how TEC varies in space and time. A statistical characterization of TEC as a function of location and time provides a solution to this problem. Suppose the vertical TEC value at location A, specified as N½(A), is determined by measurement or other means. The TEC value at some location B, denoted by N½(B), can then be estimated if the mean values ((N½(A)) and (N½(B))), as well as the correlation between [N½(A)-(N½(A)}] and [N½(B)-(N½(B))] arc known. Together, the mcan TEC variation and the TEC correlation coefficients provide sufficient information to extrapolate from single-point measurements and to assess the accuracy of the extrapolation.1Now at Ball Corporation, Broo...

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Section: Discussionmentioning

confidence: 99%

A statistical characterization of local mid‐latitude total electron content

Gail¹,

Prag²,

Coco³

et al. 1993

J. Geophys. Res.

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“…In particular, we will not consider momentum sources such as the lunar gravitational tidal force or the ion-neutral drag caused by magnetospheric electric fields. Furthermore, we will not discuss the various numerical treatments of thermosphere dynamics but will refer the reader to the review articles of Izakov [1971], Kato [1971], Murata [1974], and Dickinson [1975]. Likewise, short-periodic gravity waves are not considered in this paper.…”

Section: Introductionmentioning

confidence: 99%

Theoretical aspects of tidal and planetary wave propagation at thermospheric heights

Volland

Mayr

1977

Reviews of Geophysics

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A simple semiquantitative model is presented which allows analytic solutions of tidal and planetary wave propagation at thermospheric heights. This model is based on perturbation approximation and mode separation. The effects of viscosity and heat conduction are parameterized by Rayleigh friction and Newtonian cooling. Because of this simplicity, one gains a clear physical insight into basic features of atmospheric wave propagation. In particular, we discuss the meridional structures of pressure and horizontal wind (the solutions of Laplace's equation) and their modification due to dissipative effects at thermospheric heights. Furthermore, we solve the equations governing the height structure of the wave modes and arrive at a very simple asymptotic solution valid in the upper part of the thermosphere. That 'system transfer function' of the thermosphere allows one to estimate immediately the reaction of the thermospheric wave mode parameters such as pressure, temperature, and winds to an external heat source of arbitrary temporal and spatial distribution. Finally, the diffusion effects of the minor constituents due to the global wind circulation are discussed, and some results of numerical calculations are presented.

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“…Much of the day-to-day variability of the ionosphere is produced by corresponding variabilities in the neutral upper atmosphere, the sources of which are often unknown. However, they can be categorized as planetary waves, internal gravity waves, or acoustic-gravity waves [Murata, 1974;Yeh and Liu, 1974]. All these waves possess a characteristic similar to tidal oscillations in that they grow approximately exponentially with altitude in the atmosphere.…”

Section: Dynamicsmentioning

confidence: 99%

Current and future trends in ionospheric research

Bowhill¹

1975

Radio Science

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In the early days of upper atmosphere research, radio signals were the most useful diagnostic for studying ionospheric processes. During the space era, it has become possible to measure directly solar radiations that are screened from reaching the surface of the Earth, to measure the structure and composition of the upper atmosphere directly with in situ sensors, to conduct plasma experiments in space, to carry out remote sensing of the atmosphere from space, and to measure directly transionospheric radio propagation properties of the ionosphere. This recent dominance of space research methods in ionospheric research is becoming less marked as satellite opportunities diminish and greater emphasis is placed on studies of the ionosphere using new types of ground-based instrumentation. Looking to the t980s, the principal space flight opportunities will be associated with Spacelab, and new initiatives in ionospheric research will depend on a combined approach using all available methods for studying the dynamics and structure of the ionosphere. Future possibilities are outlined, with particular reference to new radio experiments on the ionosphere.

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Wave motions in the atmosphere and related ionospheric phenomena

Cited by 15 publications

References 237 publications

A statistical characterization of local mid‐latitude total electron content

A statistical characterization of local mid‐latitude total electron content

Theoretical aspects of tidal and planetary wave propagation at thermospheric heights

Current and future trends in ionospheric research

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