Phase and Amplitude Scintillation Statistics at 244 MHz from Goose Bay Using a Geostationary Satellite PDF Download
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Author: Sunanda Basu
Publisher:
ISBN:
Category : Artificial satellites
Languages : en
Pages : 68
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Book Description
Phase and amplitude scintillation measurements made at 244 MHz from Goose Bay using the geostationary satellite Fleetsat are presented. An extended dynamic range receiver with an extremely stable local oscillator measured the phase variations with the precision of a coherent system subject to certain limitations. The data were obtained for a 10-month period in 1979 during a high sunspot epoch to extend the limited temporal coverage of the orbiting Wideband satellite data. The report presents scintillation statistics in the manner required for communications system planning. The nighttime phase scintillations showed maximum occurrence during the spring and increased greatly in relation to the amplitude scintillations during times of significant magnetic activity. The increase of phase scintillations in relation to amplitude scintillations was attributed to an enhanced ionospheric drift during times of magnetic disturbances. The phase spectral index of the Fleetsat data was found to be larger than that determined from Wideband data. To further our understanding of auroral irregularity generation mechanisms, this report also presents a case study of energetic particle precipitation spectra, the topside thermal density response of such precipitation and the coordinated phase and amplitude perturbation spectra created by such an energy input into the ionosphere.
Author: Sunanda Basu
Publisher:
ISBN:
Category : Artificial satellites
Languages : en
Pages : 68
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Book Description
Phase and amplitude scintillation measurements made at 244 MHz from Goose Bay using the geostationary satellite Fleetsat are presented. An extended dynamic range receiver with an extremely stable local oscillator measured the phase variations with the precision of a coherent system subject to certain limitations. The data were obtained for a 10-month period in 1979 during a high sunspot epoch to extend the limited temporal coverage of the orbiting Wideband satellite data. The report presents scintillation statistics in the manner required for communications system planning. The nighttime phase scintillations showed maximum occurrence during the spring and increased greatly in relation to the amplitude scintillations during times of significant magnetic activity. The increase of phase scintillations in relation to amplitude scintillations was attributed to an enhanced ionospheric drift during times of magnetic disturbances. The phase spectral index of the Fleetsat data was found to be larger than that determined from Wideband data. To further our understanding of auroral irregularity generation mechanisms, this report also presents a case study of energetic particle precipitation spectra, the topside thermal density response of such precipitation and the coordinated phase and amplitude perturbation spectra created by such an energy input into the ionosphere.
Author:
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ISBN:
Category : Aeronautics
Languages : en
Pages : 764
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Book Description
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Author: G. J. Bishop
Publisher:
ISBN:
Category : Artificial satellites
Languages : en
Pages : 144
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An advanced system for measurement of transionospheric radio propagation effects was developed, utilizing the TI-4100 four-channel Global Positioning System (GPS) receiver. During AFGL's Polar ARCS campaign at Sondrestrom, Greenland in February-March 1987, the system successfully measured ionospheric total electron content (TEC), phase scintillation, and amplitude scintillation on both GPS carrier frequencies, from up to four satellites simultaneously. This was the first time it has been possible to measure these parameters simultaneously, in multiple directions, in the high-latitude regions. Coupled with the simultaneous optical and incoherent scatter radar diagnostics obtained during the Polar ARCS campaign, these measurements significantly improve our capability to characterize high latitude ionospheric structures, particularly their temporal and spatial variation. Additionally, the development of this advanced system has contributed significantly to the technology base for specification of the Transionospheric Sensing System (TISS) for the Air Weather Service. The system can also be software upgraded to perform special navigation in addition to ionospheric measurements in airborne applications.
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: Jules Aarons
Publisher:
ISBN:
Category : Ionosphere
Languages : en
Pages : 252
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Author: Sunanda Basu
Publisher:
ISBN:
Category : Auroras
Languages : en
Pages : 136
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Aerosol models have been developed for the lower atmosphere. These models are representative of conditions found in rural, urban, and maritime air masses. The changes in the aerosol properties with variations in the relative humidity are discussed. To describe the aerosol optical properties in the extreme of 100 percent relative humidity, several fog models are presented. For each model the coefficients for extinction, scattering, and absorption, the angular scattering distribution, and other optical parameters have been computed for wavelengths between 0.2 and 40 microns. These aerosol models are presented together with a review of their experimental basis. The optical properties of these models are discussed and some comparisons of the model with experimental measurements are presented.
Author: U.S. Air Force Geophysics Laboratory
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ISBN:
Category : Geophysics
Languages : en
Pages : 1066
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Author:
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ISBN:
Category : Environmental geology
Languages : en
Pages : 338
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Author:
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ISBN:
Category : Atmospheric chemistry
Languages : en
Pages : 914
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Author:
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ISBN:
Category : Radio meteorology
Languages : en
Pages : 504
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