Geology topics

S. Hummer-Miller

Publications and source records attributed to S. Hummer-Miller.

4 recordsLinked to original sources

USGS2012

Estimation of surface temperature variations due to changes in sky and solar flux with elevation

Sky and solar radiance are of major importance in determining the ground temperature. Knowledge of their behavior is a fundamental part of surface temperature models. These two fluxes vary with elevation and this variation produces temperature changes. Therefore, when using thermal-property differences to discriminate geologic materials, these flux variations with elevation need to be considered. From a representative set of field observations, it was found that flux variations with elevation can cause changes in the mean diurnal temperature gradient from −4° to −14°C per km evaluated at 2000 m. Changes in the temperature-difference gradient of 1°-2°C per km are also produced which is equivalent to an effective thermal-inertia gradient of 100 W s 1/2 m −2 K −1 per km. Thus, exposed bedrock on topographic ridges will appear to have a lower thermal inertia due to the additional effect.

Geophysical Research Letters↗

USGS1990

Thermal infrared exploration in the Carlin trend, northern Nevada

Experimental Thermal Infrared Multispectral Scanner (TIMS) aircraft data have been acquired for the Rodeo Creek NE 7 1/2 minute quadrangle, Eureka County, northern Nevada, covering the Carlin gold mine. A simple model has been developed to extract spectral emissivities for mapping surface lithology and alteration based on the physical properties of geologic materials. Emissivity-ratio images were prepared that allow generalized lithologic discrimination, identification of areas with high silica content, and the first reported detection of the carbonate secondary reststrahlen feature. Together with thermal-inertia images, they permit identification of areas of subtle lithologic variation not shown on conventional geologic maps. Emissivity-ratio spectra extracted from the data compare favorably with modeled laboratory spectra and establish for the first time the link among theory, measured physical properties, and color-composited TIMS images. Identification of previously unknown silicification in the Tertiary volcanic rocks and mapping of a silicified structure and possible extensions in alluvium indicate that TIMS data can be a valuable tool for detecting subtle alteration associated with mineralization, particularly in less accessible or less well-known areas.

Geophysics↗

USGS1990

Techniques for noise removal and registration of TIMS data

Extracting subtle differences from highly correlated thermal infrared aircraft data is possible with appropriate noise filters, constructed and applied in the spatial frequency domain. This paper discusses a heuristic approach to designing noise filters for removing high- and low-spatial frequency striping and banding. Techniques for registering thermal infrared aircraft data to a topographic base using Thematic Mapper data are presented. The noise removal and registration techniques are applied to TIMS thermal infrared aircraft data. -Author

Photogrammetric Engineering and Remote Sensing↗

USGS1981

A simple algorithm to estimate the effective regional atmospheric parameters for thermal-inertia mapping

A method based solely on remote sensing data has been developed to estimate those meteorological effects which are required for thermal-inertia mapping. It assumes that the atmospheric fluxes are spatially invariant and that the solar, sky, and sensible heat fluxes can be approximated by a simple mathematical form. Coefficients are determined from least-squares method by fitting observational data to our thermal model. A comparison between field measurements and the model-derived flux shows the type of agreement which can be achieved. An analysis of the limitations of the method is also provided. ?? 1981.

Remote Sensing of Environment↗