Absorption and scattering in ground-penetrating radar

Analysis of the Bishop Tuff

Robert E. Grimm, Essam Heggy, Stephen M. Clifford, Cynthia L. Dinwiddie, Ronald McGinnis, David Farrell

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

Ground-penetrating radar (GPR) signals are attenuated by both absorption and scattering. We performed low-frequency (<100 MHz) GPR surveys at the Volcanic Tableland of the Bishop (California) Tuff to evaluate the factors that control GPR depth of investigation and to develop insight into the capabilities of such radars for Mars. The subsurface reflection character was very different for two different commercial systems used; together, they revealed both internal welding contacts in the tuff and an abundance of discrete scatterers. Attenuation coefficients were computed from profiles that showed distributed scattering: the semilogarithmic signal decay is directly analogous to seismic coda. The absorption (intrinsic loss) was determined to be ∼1 dB/m from low-frequency vertical-electric soundings. The residual attenuation (that is, the attenuation in the absence of absorption) is attributed to scattering. Scattering attenuation of ∼1 dB/m at 25-50 MHz corresponds to mean-free paths as short as 4 m, a fraction of the two-way propagation distances of 20-40 m. Therefore the Bishop Tuff is formally a strong scatterer to GPR. The mean-free path is also comparable to the subsurface radar wavelength in this case, maximizing scattering loss. The scatterers themselves likely originate as welding heterogeneities; contrasts in dielectric constant due to density differences may be supplemented by moisture variations. On Mars, scattering is likely to contribute significant losses to GPR signals in all but the most uniform materials, and unfrozen thin films of water in the lower cryosphere could influence both absorption and scattering.

Original languageEnglish
Article numberE06S02
JournalJournal of Geophysical Research E: Planets
Volume111
Issue number6
DOIs
Publication statusPublished - 20 Jun 2006
Externally publishedYes

Fingerprint

ground penetrating radar
tuff
Radar
scattering
Scattering
welding
Mars
Welding
attenuation
mean free path
mars
cryosphere
coda
cryospheres
analysis
low frequencies
Permittivity
Moisture
attenuation coefficients
moisture

ASJC Scopus subject areas

  • Oceanography
  • Astronomy and Astrophysics
  • Atmospheric Science
  • Space and Planetary Science
  • Earth and Planetary Sciences (miscellaneous)
  • Geophysics
  • Geochemistry and Petrology

Cite this

Absorption and scattering in ground-penetrating radar : Analysis of the Bishop Tuff. / Grimm, Robert E.; Heggy, Essam; Clifford, Stephen M.; Dinwiddie, Cynthia L.; McGinnis, Ronald; Farrell, David.

In: Journal of Geophysical Research E: Planets, Vol. 111, No. 6, E06S02, 20.06.2006.

Research output: Contribution to journalArticle

Grimm, Robert E. ; Heggy, Essam ; Clifford, Stephen M. ; Dinwiddie, Cynthia L. ; McGinnis, Ronald ; Farrell, David. / Absorption and scattering in ground-penetrating radar : Analysis of the Bishop Tuff. In: Journal of Geophysical Research E: Planets. 2006 ; Vol. 111, No. 6.
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