Results Concerning the Sunrise Effect of VLF Signals Propagated Over Long Paths

Ries, G.

doi:10.1002/rds196726531

Cited by 25 publications

(19 citation statements)

References 15 publications

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“…A similar anomaly, becoming more severe at higher frequencies, was observed by Steele and Crombie (1967). Ries (1967) found that the first two phase steps at sunrise tended to split into substeps, with several small amplitude minima. Ries states that this effect could probably be explained by the presence of a direct second mode signal in addition to the first mode and converted second mode.…”

Section: Introductionsupporting

confidence: 72%

“…During the first part of the sunrise transition for the 9.1-Mm NBA-Frankfurt path, Ries (1967) observed small amplitude and phase variations in addition to the variations expected from Crombie's interference model. At both 18 and 24 kHz, a weak phase advance was often seen when about 0.5 Mm of the path was sunlit, in general agreement with day interference with arg (TdT 11 ) =-95°, as shown in figure 4.…”

Section: Nba-frankfurtmentioning

confidence: 67%

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Identification of a New Type of Mode Conversion Interference in VLF Propagation

Kaiser

1968

Radio Science

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The sunrise and sunset interference patterns observed in VLF propagation over long paths are largely consistent with the model of mode conversion interference proposed h.y Crombie, which considers both the first and second modes in the nighttime portion of the path, hut only the first mode in the daytime portion. Several authors, however, have reported anomalies during the first part of the sunrise transition. Except for effects produced by a direct second mode, these anomalies may be explained by a model of mode conversion interference which involves first and second mode propagation along the daytime portion of the path, and first mode propagation along the nighttime portion.

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Section: Introductionsupporting

confidence: 72%

Section: Nba-frankfurtmentioning

confidence: 67%

Identification of a New Type of Mode Conversion Interference in VLF Propagation

Kaiser

1968

Radio Science

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“…He used a model with two waveguide modes and assumed a second mode in the nocturnal part of the path with significant mode conversion at the terminator. The terminator effect has been later discussed in many papers including Walker (1965), Ries (1967), Lynn (1967, and Pappert and Snyder (1972). Clilverd et al (1999b) investigated 24-kHz signal propagation along a 12 000-km path from Cutler, Maine, to Faraday, Antarctica.…”

Section: A Background: Very Low-frequency Signal Propagationmentioning

confidence: 97%

Development of a Long-Range Lightning Detection Network for the Pacific: Construction, Calibration, and Performance*

Pessi

Businger

Cummins

et al. 2009

Journal of Atmospheric and Oceanic Technology

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The waveguide between the earth's surface and the ionosphere allows very low-frequency (VLF) emissions generated by lightning, called sferics, to propagate over long distances. The new Pacific Lightning Detection Network (PacNet), as a part of a larger long-range lightning detection network (LLDN), utilizes this attribute to monitor lightning activity over the central North Pacific Ocean with a network of groundbased lightning detectors that have been installed on four widely spaced Pacific islands (400-3800 km). PacNet and LLDN sensors combine both magnetic direction finding (MDF) and time-of-arrival (TOA)-based technology to locate a strike with as few as two sensors. As a result, PacNet/LLDN is one of the few observing systems, outside of geostationary satellites, that provides continuous real-time data concerning convective storms throughout a synoptic-scale area over the open ocean.The performance of the PacNet/LLDN was carefully assessed. Long-range lightning flash detection efficiency (DE) and location accuracy (LA) models were developed with reference to accurate data from the U.S. National Lightning Detection Network (NLDN). Model calibration procedures are detailed, and comparisons of model results with lightning observations from the PacNet/LLDN in correlation with NASA's Lightning Imaging Sensor (LIS) are presented. The daytime and nighttime flash DE in the northcentral Pacific is in the range of 17%-23% and 40%-61%, respectively. The median LA is in the range of 13-40 km. The results of this extensive analysis suggest that the DE and LA models are reasonably able to reproduce the observed performance of PacNet/LLDN.The implications of this work are that the DE and LA model outputs can be used in quantitative applications of the PacNet/LLDN over the North Pacific Ocean and elsewhere. For example, by virtue of the relationship between lightning and rainfall rates, these data also hold promise as input for NWP models as a proxy for latent heat release in convection. Moreover, the PacNet/LLDN datastream is useful for investigations of storm morphology and cloud microphysics over the central North Pacific Ocean. Notably, the PacNet/LLDN lightning datastream has application for planning transpacific flights and nowcasting of squall lines and tropical storms.

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“…A vast literature of such examples exists going back to the 1960s (e.g. [33] [39]). Weaker mode conversion at the more extended sunset transition produces reduced fading in comparison with the much stronger fading in signal strength and phase oscillation during the sunrise transition.…”

Section: Terminator-generated Modal Interferencementioning

confidence: 99%

VLF Waveguide Propagation: The Basics

Lynn¹

2010

AIP Conference Proceedings

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In recent times, research has moved towards using VLF radio transmissions propagating in the earth-ionosphere waveguide as a detector of a variety of transient geophysical phenomena. A correct interpretation of such results depends critically on understanding the propagation characteristics of the path being monitored. The observed effects will vary depending on time of day, path length, path orientation, magnetic latitude and VLF frequency. This paper provides a brief tutorial of the relevant propagation dependencies for medium to long VLF paths best understood in terms of waveguide mode theory together with results either not previously published, not published in the open scientific literature or whose significance has been little recognised.

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Results Concerning the Sunrise Effect of VLF Signals Propagated Over Long Paths

Cited by 25 publications

References 15 publications

Identification of a New Type of Mode Conversion Interference in VLF Propagation

Identification of a New Type of Mode Conversion Interference in VLF Propagation

Development of a Long-Range Lightning Detection Network for the Pacific: Construction, Calibration, and Performance*

VLF Waveguide Propagation: The Basics

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