Evaluation of an empirical radar backscatter model for predicting backscatter characteristics of geologic units at Pisgah Volcanic Field, California
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Abstract
Comparison of radar backscatter coefficients (σ°, in dB), calculated by using the empirical model of Oh et al. [1992], to σ° extracted from AIRSAR data of four geologic units at Pisgah shows that the model predicts measured σ°vv and σ°hv to within ±3 dB. The model predicts higher σ°hh than those observed. For smooth surfaces (rms height=s, s<8 cm), model results depend strongly on the accuracy of the surface measurements ( s and dielectric constant, ϵr). For rougher surfaces, the model is less dependent on the accuracy of surface characterizations. The model may be inverted to estimate s from measured σ° for surfaces with ks<3 (k = wavenumber, or 2π/λ, where λ = radar wavelength). Model inversion for a pahoehoe unit at 30° to 50° incidence angles (θ) resulted in an estimate of s to within <1 cm of the measured 3 cm. The inability of the model to estimate accurately σ°hh and the anomalously high nadir Fresnel reflection coefficients (Γo) and ϵr required in the model inversion may both be due to ∼equal co‐polarized ratios (σ°hh/σ°vv=p∼1) of the soils used to derive the model. For effective application to many geologic surfaces, for which p<1 is often observed at θ>30°, the model will require modification to include surfaces with non‐unity σ°hh/σ°vv.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Evaluation of an empirical radar backscatter model for predicting backscatter characteristics of geologic units at Pisgah Volcanic Field, California |
| Series title | Geophysical Research Letters |
| DOI | 10.1029/94GL01253 |
| Volume | 21 |
| Issue | 17 |
| Year Published | 1994 |
| Language | English |
| Publisher | American Geophysical Union |
| Contributing office(s) | Astrogeology Science Center |
| Description | 4 p. |
| First page | 1803 |
| Last page | 1806 |
| Country | United States |
| State | California |
| Other Geospatial | Pisgah Volcanic Field |
| Google Analytic Metrics | Metrics page |