Quantifying Subsurface Propagation Losses for VHF Radar Sounding Waves in Hyper-Arid Terrains

Scabbia, Giovanni; Heggy, E.

doi:10.1109/igarss.2018.8517891

Cited by 5 publications

(3 citation statements)

References 9 publications

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“…These losses are described by the radar equation (Annan & Davis, 1977; Skolnik, 2008), the ratio of the reflected power to the transmitted power:

\frac{{P}_{R}}{{P}_{T}}=\frac{{G}^{2}{\lambda }^{2}\xi }{64{\pi }^{3}{R}^{4}}{e}^{-4\alpha R}

where G is antenna gain, λ is the radar wavelength, ξ is the backscatter cross‐section, α is the intrinsic attenuation coefficient, and R is the distance to the reflecting target. After correcting the relative amplitudes for these effects, total attenuation can be isolated from the average trace (Annan & Davis, 1977; Boisson et al., 2011; Grimm et al., 2006; Scabbia & Heggy, 2018).…”

Section: Methodsmentioning

confidence: 99%

“…where G is antenna gain, λ is the radar wavelength, ξ is the backscatter cross-section, α is the intrinsic attenuation coefficient, and R is the distance to the reflecting target. After correcting the relative amplitudes for these effects, total attenuation can be isolated from the average trace (Annan & Davis, 1977;Boisson et al, 2011;Grimm et al, 2006;Scabbia & Heggy, 2018).…”

Section: Quantifying Losses To the Radar Signalmentioning

confidence: 99%

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Mapping Ice Buried by the 1875 and 1961 Tephra of Askja Volcano, Northern Iceland Using Ground‐Penetrating Radar: Implications for Askja Caldera as a Geophysical Testbed for In Situ Resource Utilization

Shoemaker,

Baker,

Richardson

et al. 2024

JGR Planets

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Eruptions of the Askja Volcano in Northern Iceland in 1875 and 1961 blanketed the caldera with rhyolitic and basaltic tephra deposits, respectively, which preserved layers of seasonal snowpack as massive ice. Askja serves as an operational and geophysical analog to test ground‐penetrating radar field and analysis techniques for in situ resource utilization objectives relevant to the martian and lunar environments. We conducted ground‐penetrating radar surveys at center frequencies of 200, 400, and 900 MHz to map the thickness and extent of tephra deposits and underlying massive ice at three caldera sites. We identified up to 1 m of tephra preserving up to 4.4 m of massive ice. We measured the real dielectric permittivity of the overlying tephra and the total attenuation at each frequency of the tephra and ice. A key objective of our investigation was to determine if attenuation (or loss) could be used as an additional diagnostic signature of massive ice preserved at depth when compared to ice‐free stratigraphy. Loss rates of the ice‐rich subsurface decrease with increasing ice thickness relative to the overburden, which may constitute a possible signature. Attenuation also increased with increasing frequency. The tephra, ice, and other volcanic deposits at each of our three caldera sites and the ice‐free, pumice‐mantled 1961 Vikrahraun lava flow exhibited consistently low loss rates at all frequencies. This result highlights the ambiguity associated with identifying the unique signature of ice within low‐loss stratigraphies, a possible challenge for its identification in the martian or lunar subsurface using radar.

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“…These losses are described by the radar equation (Annan & Davis, 1977; Skolnik, 2008), the ratio of the reflected power to the transmitted power:

\frac{{P}_{R}}{{P}_{T}}=\frac{{G}^{2}{\lambda }^{2}\xi }{64{\pi }^{3}{R}^{4}}{e}^{-4\alpha R}

Section: Methodsmentioning

confidence: 99%

Section: Quantifying Losses To the Radar Signalmentioning

confidence: 99%

Mapping Ice Buried by the 1875 and 1961 Tephra of Askja Volcano, Northern Iceland Using Ground‐Penetrating Radar: Implications for Askja Caldera as a Geophysical Testbed for In Situ Resource Utilization

Shoemaker,

Baker,

Richardson

et al. 2024

JGR Planets

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“…Laboratory characterization of the dielectric properties of samples collected from hyper-arid environments confirm that the majority of the Sahara and Arabian Peninsula is covered with erosional sediments mostly rich in desiccated silicates that HEGGY ET AL. 2023: RADAR PROBING OF SHALLOW AQUIFERS exhibit low two-way dielectric and scattering losses ranging from ~0.5 to 0.9 dB/m [44]- [47]. Furthermore, GPR measurements on dunes in semi-arid and coastal environments allow sufficient penetration to assess their internal layering [48]- [62].…”

Section: Introductionmentioning

confidence: 99%

Probing Shallow Aquifers in Hyperarid Dune Fields Using VHF Sounding Radar

Heggy,

Normand,

Palmer

et al. 2023

IEEE Trans. Geosci. Remote Sensing

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Large-scale characterization of water table depth in shallow aquifers in hyper-arid areas provides crucial insights into groundwater dynamics under increasing anthropogenic discharge and climatic fluctuations. Due to their penetration capabilities into arid soils, airborne VHF sounding radars can achieve this objective under specific system design, topographic and geophysical constraints, superseding sporadic well logs and ground-based surveys that provide compromised assessments of the distribution and depth of these water bodies. One of the least constrained ambiguities limiting the design of such systems, however, is the maximum penetration depth in desiccated sandy soils, which cover a sizeable fraction of desert landscapes. To constrain the latter, we perform a ground survey using 50-and-80-MHz GPRs with effective dynamic ranges of ~80-dB at the surface to probe the unconfined aquifer under desiccated linear dunes in the Wahiba Sands in Oman. Our survey resolves the water table down to at least 69-m depth, the deepest achieved at VHF frequencies in hyper-arid terrains. We observe the average twoway plane-wave subsurface radar attenuation, accounting for both dielectric and scattering losses, to range from 0.1-to-1.4-dB/m through these sandy formations. Dielectric and scattering losses can be of equal magnitude depending on the sounding frequency and stratigraphic setting of the subsurface. Penetration depths to the water table are validated with TDEM measurements and welllog data. Additionally, we identify shallow paleochannels from Lband SAR observations that suggest modern meteoritic recharge of the probed aquifer, creating shallow localized anomalous losses in the radar signal in the first few meters. We conclude that the minimum requirements for an airborne VHF sounding radar to probe shallow aquifers at depths of tens of meters in sandy formations in hyper-arid areas are an SNR of 55-dB at the surface, a bandwidth of 10-MHz, and a surface hrms not exceeding 2 m.

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Quantifying the influence of transmission path characteristics on urban railway noise

kumar

Chowdary

2023

Environ Monit Assess

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Quantifying Subsurface Propagation Losses for VHF Radar Sounding Waves in Hyper-Arid Terrains

Cited by 5 publications

References 9 publications

Mapping Ice Buried by the 1875 and 1961 Tephra of Askja Volcano, Northern Iceland Using Ground‐Penetrating Radar: Implications for Askja Caldera as a Geophysical Testbed for In Situ Resource Utilization

Mapping Ice Buried by the 1875 and 1961 Tephra of Askja Volcano, Northern Iceland Using Ground‐Penetrating Radar: Implications for Askja Caldera as a Geophysical Testbed for In Situ Resource Utilization

Probing Shallow Aquifers in Hyperarid Dune Fields Using VHF Sounding Radar

Quantifying the influence of transmission path characteristics on urban railway noise

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