Item talk:Q305447

{

 "USGS Publications Warehouse": {
   "@context": "https://schema.org",
   "@type": "Article",
   "additionalType": "Journal Article",
   "name": "Evaluation of an empirical radar backscatter model for predicting backscatter characteristics of geologic units at Pisgah Volcanic Field, California",
   "identifier": [
     {
       "@type": "PropertyValue",
       "propertyID": "USGS Publications Warehouse IndexID",
       "value": "70202099",
       "url": "https://pubs.usgs.gov/publication/70202099"
     },
     {
       "@type": "PropertyValue",
       "propertyID": "USGS Publications Warehouse Internal ID",
       "value": 70202099
     },
     {
       "@type": "PropertyValue",
       "propertyID": "DOI",
       "value": "10.1029/94GL01253",
       "url": "https://doi.org/10.1029/94GL01253"
     }
   ],
   "journal": {
     "@type": "Periodical",
     "name": "Geophysical Research Letters",
     "volumeNumber": "21",
     "issueNumber": "17"
   },
   "inLanguage": "en",
   "isPartOf": [
     {
       "@type": "CreativeWorkSeries",
       "name": "Geophysical Research Letters"
     }
   ],
   "datePublished": "1994",
   "dateModified": "2019-02-11",
   "abstract": "Comparison of radar backscatter coefficients (\u03c3\u00b0, in dB), calculated by using the empirical model of Oh et al. [1992], to \u03c3\u00b0 extracted from AIRSAR data of four geologic units at Pisgah shows that the model predicts measured \u03c3\u00b0vv\u00a0and \u03c3\u00b0hv\u00a0to within \u00b13 dB. The model predicts higher \u03c3\u00b0hh\u00a0than those observed. For smooth surfaces (rms height=s,\u00a0s<8 cm), model results depend strongly on the accuracy of the surface measurements (\u00a0s\u00a0and dielectric constant, \u03f5r). For rougher surfaces, the model is less dependent on the accuracy of surface characterizations. The model may be inverted to estimate\u00a0s\u00a0from measured \u03c3\u00b0 for surfaces with\u00a0ks<3 (k\u00a0= wavenumber, or 2\u03c0/\u03bb, where \u03bb = radar wavelength). Model inversion for a pahoehoe unit at 30\u00b0 to 50\u00b0 incidence angles (\u03b8) resulted in an estimate of\u00a0s\u00a0to within <1 cm of the measured 3 cm. The inability of the model to estimate accurately \u03c3\u00b0hh\u00a0and the anomalously high nadir Fresnel reflection coefficients (\u0393o) and \u03f5r\u00a0required in the model inversion may both be due to \u223cequal co\u2010polarized ratios (\u03c3\u00b0hh/\u03c3\u00b0vv=p\u223c1) of the soils used to derive the model. For effective application to many geologic surfaces, for which p<1 is often observed at \u03b8>30\u00b0, the model will require modification to include surfaces with non\u2010unity \u03c3\u00b0hh/\u03c3\u00b0vv.",
   "description": "4 p.",
   "publisher": {
     "@type": "Organization",
     "name": "American Geophysical Union"
   },
   "author": [
     {
       "@type": "Person",
       "name": "Gaddis, Lisa R. lgaddis@usgs.gov",
       "givenName": "Lisa R.",
       "familyName": "Gaddis",
       "email": "lgaddis@usgs.gov",
       "identifier": {
         "@type": "PropertyValue",
         "propertyID": "ORCID",
         "value": "0000-0001-9953-5483",
         "url": "https://orcid.org/0000-0001-9953-5483"
       },
       "affiliation": [
         {
           "@type": "Organization",
           "name": "Astrogeology Science Center",
           "url": "https://www.usgs.gov/centers/astrogeology-science-center"
         }
       ]
     }
   ],
   "funder": [
     {
       "@type": "Organization",
       "name": "Astrogeology Science Center",
       "url": "https://www.usgs.gov/centers/astrogeology-science-center"
     }
   ],
   "spatialCoverage": [
     {
       "@type": "Place",
       "additionalType": "country",
       "name": "United States",
       "url": "https://geonames.org/4074035"
     },
     {
       "@type": "Place",
       "additionalType": "state",
       "name": "California"
     },
     {
       "@type": "Place",
       "additionalType": "unknown",
       "name": "Pisgah Volcanic Field"
     }
   ]
 }

}