Global Morphology of Ionospheric Scintillations II PDF Download
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Author: Jules Aarons
Publisher:
ISBN:
Category : F region
Languages : en
Pages : 30
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Book Description
Updating a review of the global morphology of ionospheric scintillations published in 1971, this study adds additional experimental studies on familiar topics to newer types of measurements of ionospheric irregularities, including in situ experiments and artificial heating of the F-layer.
Author: Jules Aarons
Publisher:
ISBN:
Category : F region
Languages : en
Pages : 30
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Book Description
Updating a review of the global morphology of ionospheric scintillations published in 1971, this study adds additional experimental studies on familiar topics to newer types of measurements of ionospheric irregularities, including in situ experiments and artificial heating of the F-layer.
Author: Jules Aarons
Publisher:
ISBN:
Category : Geostationary satellites
Languages : en
Pages : 48
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Book Description
Amplitude fluctuations produced by small irregularities in electron density in the F-layer of the ionosphere (at 300 to 400 km height) can be a problem to communication and navigation systems in the VHF-UHF range. Recent measurements, primarily by AFCRL, are shown with emphasis on results at high and equatorial latitudes. At high latitudes an irregularity region exists whose lower boundary reaches 57 degrees invariant latitude near midnight. During magnetic storms the boundary descends to lower latitudes and the fading becomes deeper. Over the polar cap scintillations are somewhat diminished. When observing synchronous satellites through the irregularity region, deep and fast fading is frequently seen, with fade rates to one per second. Irregularities produce deep scintillations in the VHF range plus or minus 15 degrees from the geomagnetic equator. In equatorial regions maximum occurrence of high level scintillations takes place between 2100 and 2400 local time during the equinoxes; a minimum occurrence is observed during the solstices. When the sunspot number decreases, the equatorial irregularity region spreads and becomes larger. The data for various latitudes has been placed in statistical form, that is, distribution of amplitudes for 15-min samples as well as for periods of 1 yr and longer. (Author).
Author: H. E. Whitney
Publisher:
ISBN:
Category : Artificial satellites
Languages : en
Pages : 28
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Book Description
Author: Eileen MacKenzie
Publisher:
ISBN:
Category : Auroras
Languages : en
Pages : 52
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Book Description
The orbiting HiLat satellite launched in 1983 offered an opportunity for studying ionospheric scintillation parameters in relation to in-situ measurements of ionization density, drift velocity, field-aligned current, and particle precipitation during the sunspot minimum period. This report discusses results of a morphological study based on observations of scintillations and total electron content (TEC) at the auroral oval station at Tromso, Norway, during the period Dec 1983 - Oct 1985. The geometrical enhancement of scintillations observed during alignment of the propagation with the local magnetic L-shell is shown to be the most consistent and conspicuous feature of scintillations in the nighttime auroral oval. The dynamics of the spatial and temporal extent of this region are illustrated in the invariant latitude/magnetic local time grid. Steepening of phase spectral slope in the geometrical enhancement region is indicative of the presence of L-shell aligned sheet-like irregularities at long scale lengths. The seasonal variation of TEC determined from the differential Doppler measurements of HiLat transmissions is discussed in relation to the in-situ density measurements at 830 km. The results are also used to illustrate the dependence of ionospheric structure parameters on short-term variability of solar activity during the sunspot minimum period. This study provides an insight into the nature of magnetospheric coupling with the ionosphere at high latitudes.
Author: Chao Huang
Publisher: John Wiley & Sons
ISBN: 1119507553
Category : Science
Languages : en
Pages : 47
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Book Description
A comprehensive review of global ionospheric research from the polar caps to equatorial regions It's more than a century since scientists first identified the ionosphere, the layer of the Earth’s upper atmosphere that is ionized by solar and cosmic radiation. Our understanding of this dynamic part of the near-Earth space environment has greatly advanced in recent years thanks to new observational technologies, improved numerical models, and powerful computing capabilities. Ionosphere Dynamics and Applications provides a comprehensive overview of historic developments, recent advances, and future directions in ionospheric research. Volume highlights include: Behavior of the ionosphere in different regions from the poles to the equator Distinct characteristics of the high-, mid-, and low-latitude ionosphere Observational results from ground- and space-based instruments Ionospheric impacts on radio signals and satellite operations How earthquakes and tsunamis on Earth cause disturbances in the ionosphere The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals. Find out more about the Space Physics and Aeronomy collection in this Q&A with the Editors in Chief
Author: John M. Goodman
Publisher:
ISBN:
Category : Astronautics
Languages : en
Pages : 520
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Book Description
Author:
Publisher:
ISBN:
Category : Astronautics
Languages : en
Pages : 522
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Book Description
Author: Jules Aarons
Publisher:
ISBN:
Category : Artificial satellites in telecommunication
Languages : en
Pages : 40
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Book Description
With the advent of satellite communications systems at frequencies varying from approx. 140 to 1600 MHz, as well as navigation and ranging systems in the 1200 to 1600-MHz portions of the spectrum, the effect of equatorial irregularities on fading signals has become of importance. Recent observations of the signal statistics of scintillations at frequencies ranging from 136 MHz to 6 GHz reveal a power-law falloff of irregularity sizes. Power spectra are now available for a variety of conditions and for frequencies from vhf to microwaves. during periods of intense equatorial activity at frequencies to 360 MHz, Rayleigh scattering is frequently experienced.
Author:
Publisher:
ISBN:
Category : Artificial satellites
Languages : en
Pages : 638
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Book Description
Author: Jules Aarons
Publisher:
ISBN:
Category : Artificial satellites
Languages : en
Pages : 64
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Book Description
Using observations of the scintillations of beacons from synchronous satellites, a high latitude model of scintillation excursion is being developed. Phase 1 of the development has been completed and is described in this report. Several years of continuous recordings taken at Narssarssuaq, Greenland, Goose Bay, Labrador, and Sagamore Hill, Massachusetts, were reduced. The data base consists of values of 15-min scintillation excursions in dB at 137 MHz. Equations are developed which yield scintillations at this frequency as a function of local time, magnetic index, solar flux, and month of the year. The concept is to predict, at sub-auroral and auroral latitudes, scintillation at this frequency and at higher frequencies. The aim is to give to users an indication of expected scintillation excursion when one predicts magnetic activity and solar radio flux. The equations developed have been checked with one additional set of observations and are being checked with additional data. Phase 2 of this model will incorporate geometrical terms to take account of the propagation angle of the observer vis-a-vis the irregularities and will allow for frequency dependence to be ascertained. In addition, it is expected in Phase 2 to validate the model with additional sets of data, extending the model to auroral latitudes greater than 63 deg. and to polar latitudes. (Author).
