Duct occurrence and characteristics for Bulgarian Black sea shore derived from ECMWF data

Sirkova, I.

doi:10.1016/j.jastp.2015.10.017

Cited by 24 publications

(20 citation statements)

References 25 publications

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“…The coastal zone is characterized by changes in duct height and Mdeficit as one goes from the shore to the sea and vice versa. The correct assessment of propagation conditions in those zones requires knowledge of meteorological data along the entire propagation path [16,18]. The horizontal resolution in the case of range-dependent profiles is still to be determined for the specific area.…”

Section: Unresolved Issues and Possible Source Of Errorsmentioning

confidence: 99%

“…Above mentioned models and tools are accompanied with increasing improvement in lower troposphere refractivity and sea state estimation/analysis in different area of the world and sophisticated refractive environmental modeling including inversion techniques [15][16][17][18][19]. In [18] are summarized the last 20 years field campaigns for data collection whereas [19] reviews previous work in estimating the atmospheric conditions from electromagnetic measurements which assures real-time tracking of atmospheric parameters.…”

Section: Introductionmentioning

confidence: 99%

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Anomalous tropospheric propagation: Usage possibilities and limitations in radar and wireless communications systems

Sirkova¹

2019

AIP Conference Proceedings

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The anomalous tropospheric propagation due to extreme superrefraction of radio waves (known also as ducting) has significant influence on radar and communication systems working in microwave range. Up to the last decade tropospheric ducting has been considered rather an unwanted phenomenon as it causes multipath propagation (with all related impairments on communications systems), missed target detection for radars, unexpected interference between different microwave systems working in the same range, etc. The tropospheric ducting mechanism is more typical for coastal and maritime areas than over land. On the other hand, the coastal and maritime areas are known to cause difficulties in planning and designing of the communications links due to the high environmental variability there. During the last years, the development of accurate operational propagation prediction/assessment models and the increasing improvement in meteorological data collection and environmental models gave rise to the idea of making use of the most common effect of ducting, namely, the long-range radio waves propagation leading to signal enhancement near and beyond the radio horizon. This paper aims at outlining the state, achievements and limitations in the usage of tropospheric ducting mechanism to maintain efficient coastal communications links. Reliability of such links from physical layer point of view, advantages and disadvantages of operational propagation and environmental models will be discussed.

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Section: Unresolved Issues and Possible Source Of Errorsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Anomalous tropospheric propagation: Usage possibilities and limitations in radar and wireless communications systems

Sirkova¹

2019

AIP Conference Proceedings

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“…However, the meteorological element fields in the atmospheric boundary layer are variable, and the resultant abnormal propagation conditions will seriously affect the regular operation and performance evaluation of radio devices [1][2][3]. Notably, the trapping structures formed in the states of temperature and humidity inversion, i.e., tropospheric ducts, can make the radio waves propagate towards the ground, resulting in the occurrence of over-the-horizon propagation [4,5]. For example, the ground clutters caused by super refraction at a lower radar elevation angle can degrade the quality of weather radar products potentially [6].…”

Section: Introductionmentioning

confidence: 99%

Inversion for Inhomogeneous Surface Duct without a Base Layer Based on Ocean-Scattered Low-Elevation BDS Signals

Liu

Cao

et al. 2021

Remote Sensing

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The anomalous propagation conditions, particularly the tropospheric ducts, severely impact the regular operation and performance evaluation of radio devices in the atmospheric boundary layer. Therefore, it is necessary to provide the regional distribution of tropospheric ducts for utilizing or avoiding these abnormal propagation phenomena. As significant uncooperative signal sources, the global navigation satellite systems (GNSS) have been widely applied in the remote sensing of the ocean and atmosphere due to the greater convenience and lower cost. With the completed deployment of the BeiDou Navigation Satellite System (BDS) in 2020, an additional source can be chosen in the relevant studies. Taking the BDS as an example, since the scattered signals from the ocean surface at low satellite elevation angles can be effectively trapped by tropospheric ducts, we propose a method to invert for the regional distribution of tropospheric ducts using the received power of ocean-scattered signals in this paper. Firstly, the propagation model was built to calculate the received power, and a suite of simulations was made in various atmospheric environments. The results suggested that the received power is more sensitive to the surface duct without a base layer. Then, we made a preliminary estimation of the tropospheric ducts on the ocean nearby Qingdao utilizing the Weather Research and Forecasting (WRF) model as well as the echo data measured by a Doppler weather radar. Before the inversion, the actual satellite azimuth and elevation angles should be obtained to evaluate the bistatic scattering coefficients and the received powers of the selected satellite signals. Finally, we presented an inversion example using the proposed method. In absence of the actual measurements, the received powers pre-estimated at different SNRs served as the inputs of the inversion process and the estimated duct parameters were used to verify the validity of the proposed inversion method. For both the received power and modified refractivity profile, the fitness between the values pre-estimated using the estimated duct parameters and calculated by the inverted duct parameters gets better as the elevation angle decreases and the SNR increases. The variation of the fitness between the estimated and inverted values is slightly different for each duct parameter. Moreover, the calculation of inversion errors further explained the above behaviors, including the mean absolute error (MAE) and the root mean square error (RMSE). Despite some certain errors, the inversion results maintain the overall tendencies and most characteristics of the estimated values, thus proving the validity of the inversion method.

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“…Manjula et al [1] used high-resolution vertical and temporal radiosonde measurements to study the diurnal variation in ducting over the Indian tropical region. Sirkova [2] reported on the occurrence and properties of tropospheric ducts along the Bulgarian shore of the Black Sea. Kaissassou et al [3] used six years (2006-2011) of situ measurements of temperature, moisture, and pressure made by the Agency for the Safety of Air Navigation in Africa and Madagascar to determine the conditions for surface ducts over the Ngaoundere region.…”

Section: Introductionmentioning

confidence: 99%

Spatiotemporal Distribution of Atmospheric Ducts in Alaska and Its Relationship with the Arctic Vortex

Mai

Sheng

Shi

et al. 2020

International Journal of Antennas and Propagation

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Duct occurrence and characteristics for Bulgarian Black sea shore derived from ECMWF data

Cited by 24 publications

References 25 publications

Anomalous tropospheric propagation: Usage possibilities and limitations in radar and wireless communications systems

Anomalous tropospheric propagation: Usage possibilities and limitations in radar and wireless communications systems

Inversion for Inhomogeneous Surface Duct without a Base Layer Based on Ocean-Scattered Low-Elevation BDS Signals

Spatiotemporal Distribution of Atmospheric Ducts in Alaska and Its Relationship with the Arctic Vortex

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