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Author: Jules Aarons
Publisher:
Published: 1975
Total Pages: 30
ISBN-13:
DOWNLOAD EBOOKUpdating 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:
Published: 1970
Total Pages: 48
ISBN-13:
DOWNLOAD EBOOKAmplitude 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: Jules Aarons
Publisher:
Published: 1975
Total Pages: 0
ISBN-13:
DOWNLOAD EBOOKAuthor: UNITED STATES. DEPARTMENT OF THE AIR FORCE. AIR FORCE SYSTEMS COMMAND. AIR FORCE CAMBRIDGE RESEARCH LABORATORIES.
Publisher:
Published: 1975
Total Pages: 39
ISBN-13:
DOWNLOAD EBOOKAuthor: Jules Aarons
Publisher:
Published: 1970
Total Pages: 0
ISBN-13:
DOWNLOAD EBOOKAmplitude 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: Shishir Priyadarshi
Publisher:
Published: 2022
Total Pages: 0
ISBN-13:
DOWNLOAD EBOOKThe wavelength of the radio-wave satellite signal is of the order of the minimal small-scale ionospheric irregularities (i.e., a few centimeters). As the satellite signal passes through the ionosphere, its interaction with the ionospheric irregularity structures causes refraction, reflection, and polarization in the satellite signal. Ionospheric irregularities degrade the trans-ionospheric radio-wave signal quality, between the satellite and the receivers, due to scintillation. The physics-based model often fails to produce global morphology during the extreme solar events, whereas empirical models based on the ionospheric scintillation data demonstrate better quality to forecast the scintillation effects during extreme solar event. It is really tricky to make a scintillation model that is sensitive to low and high solar activities as well as extreme solar events simultaneously. In the presented book chapter, we will discuss/review the needs and tricks of modeling ionospheric scintillation during extreme solar events as well as all weather and latitudinal cases. There are several aspects that influence the scintillation occurrence, its strength, and global distribution. The latitudinal dependence, local weather, solar/geomagnetic activity conditions, and local times are the widely accepted factors that control and influence ionospheric scintillation most. This book chapter discusses all these aspects and also suggests the ways to cast aside those factors that led to the wrong measure of scintillation indices.
Author: Eileen MacKenzie
Publisher:
Published: 1987
Total Pages: 52
ISBN-13:
DOWNLOAD EBOOKThe 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
Published: 2021-05-11
Total Pages: 47
ISBN-13: 1119507553
DOWNLOAD EBOOKA 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: Robert K. Crane
Publisher:
Published: 1974
Total Pages: 93
ISBN-13:
DOWNLOAD EBOOKThe report is directed toward providing information to communication systems designers first about scintillation as observed in a single experiment, second about the adequacy of the existing models used to interpret scintillation data, and finally about the variation of scintillation with geophysical parameters.
Author: H. E. Whitney
Publisher:
Published: 1976
Total Pages: 28
ISBN-13:
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