A Statistical Study of Anomalous VHF Propagation Due to the Sporadic‐E Layer in the Air‐Navigation Band

Sakai, Jun; Hosokawa, K.; Tomizawa, Ichiro; Saito, Susumu

doi:10.1029/2018rs006781

Cited by 20 publications

(25 citation statements)

References 11 publications

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“…We are most interested in ILS ID 17 on which very strong signal (>−95 dBm) is recorded continuously for more than 3 hr. A group of vertical traces at around 18 JST is supposed to be artificial noise (Sakai et al, 2019).…”

Section: Space Weathermentioning

confidence: 99%

Anomalous Propagation of Radio Waves from Distant ILS Localizers Due to Ionospheric Sporadic‐E

et al. 2020

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The ionospheric sporadic‐E (Es) layer occasionally causes anomalous propagation (AP) of VHF radio waves to distant locations. This effect, EsAP, may cause interference to VHF radio operation above 100 MHz. Recent study showed that VHF air navigation signals from distant stations are frequently observed when Es occurs. The observed frequencies includes channels of VHF omnidirectional radio range (VOR) and instrument landing system localizer (ILS LOC). The study showed that EsAP signals can be very strong and frequently exceeded the allowable interference limit of navigation receivers. In this paper, we focus on EsAP on ILS LOC channels using the data obtained in the previous study. A series of extremely strong signals was observed on an ILS LOC frequency at Kure, Japan, on 15 May 2014 when an ionosphere sounder observed high‐density Es. The source of the signal was identified as an ILS LOC‐type direction aid (LDA) at Hualien, Taiwan. During the same period, several EsAP signals were observed on other ILS LOC channels, but their strengths were less significant. Analysis showed the causes of the strong signal from Hualien LDA: (1) the center of the narrow radio beam passed through the region very close to the receiver site; (2) the elevation angle of the propagation path was very close to that of the actual beam center. Statistics showed that there were several outstanding EsAP events of which source was Hualien LDA. This study suggests that if similar conditions exist, radio interference to ILS LOC receiver can happen on any ILS LOC channels.

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Section: Space Weathermentioning

confidence: 99%

Anomalous Propagation of Radio Waves from Distant ILS Localizers Due to Ionospheric Sporadic‐E

et al. 2020

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“…E s layers have been studied extensively since the middle of the twentieth century because they cause anomalous propagation of radio waves utilized for communication and broadcast (e.g., Whitehead 1970). More recently, it became known that the E s layers have a potential impact on air-navigation applications using very high frequency waves (Sakai et al 2019).…”

Section: Introductionmentioning

confidence: 99%

First simulations of day-to-day variability of mid-latitude sporadic E layer structures

Andoh

Saito

Shinagawa

et al. 2020

Earth Planets Space

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We present the first simulations that successfully reproduce the day-to-day variability of the mid-latitude sporadic E ($$E_s$$ E s ) layers. $$E_s$$ E s layers appearing in the lower ionosphere have been extensively investigated to monitor and forecast their effects on long-distance communication by radio waves. Although it is widely accepted that the atmospheric tides are important in generating the $$E_s$$ E s layers, no simulations to date have reproduced the $$E_s$$ E s layers observed on a certain day. This is due to the lack of the combination of realistic information on the atmospheric tides in the lower ionosphere and a three-dimensional numerical ionospheric model that can simulate the precise transport of metallic ions. We developed a numerical ionospheric model coupled with the neutral winds from the GAIA (Ground-to-topside model of Atmosphere and Ionosphere for Aeronomy). The fundamental structures and the day-to-day variations of the $$E_s$$ E s layers observed by a $$\hbox {Ca}^+$$ Ca + lidar are well-reproduced in the simulations.

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“…The effects of Es on analogue television and FM radio in such a frequency range have been well-known for a long time. Recently, Sakai et al (2019Sakai et al ( , 2020 demonstrated that propagation of VHF radio waves used for aeronautical navigation (so-called NAV signals at 108-118 MHz range) has also been affected by the appearance of Es. In particular, they statistically showed that Es anomalous propagation (EsAP) of NAV signals often occurs in Japan during summer months.…”

Section: Introductionmentioning

confidence: 99%

Visualizing sporadic E using aeronautical navigation signals at VHF frequencies

Hosokawa

Kimura

Sakai

et al. 2021

J. Space Weather Space Clim.

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To understand the dynamical properties of sporadic E layer (Es), we have developed a method to visualize the two-dimensional spatial structure of Es by monitoring the occurrence of anomalous propagation of VHF waves used for aeronautical navigation systems in combination with the electron density disturbance index ROTI, that is the Rate of total electron content (TEC) Index obtained from ground-based GPS receivers. We introduce a case of strong Es layer which occurred for ~4 h during daytime of July 4, 2019. In this interval, we succeeded in imaging the structure of Es elongating more in the east–west direction and moving northward gradually. This result indicates that the combination of network observations of aeronautical navigation signals and ROTI is capable of imaging the 2D structure of Es in a wide area including the sea surface, which enables us to discuss the dynamical characteristics and generation mechanism of Es.

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A Statistical Study of Anomalous VHF Propagation Due to the Sporadic‐E Layer in the Air‐Navigation Band

Cited by 20 publications

References 11 publications

Anomalous Propagation of Radio Waves from Distant ILS Localizers Due to Ionospheric Sporadic‐E

Anomalous Propagation of Radio Waves from Distant ILS Localizers Due to Ionospheric Sporadic‐E

First simulations of day-to-day variability of mid-latitude sporadic E layer structures

Visualizing sporadic E using aeronautical navigation signals at VHF frequencies

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