Document Type

Thesis - Open Access

Award Date

1980

Degree Name

Master of Science (MS)

Department

Physics

First Advisor

Jerald A. Turnheim

Abstract

Recent launchings of satellites with thermal infrared imagery sensors, together with those planned in the near future, hold great promise for application of thermal emittance data as a tool for resource management and development. These earth resources satellites allow time-sequential monitoring of land-surface emittance over large areas of the earth at relatively low cost allowing data to be readily available on a routine basis for use by the resource specialist in making management decisions. The use of thermography for monitoring soil moisture is based on the sensitivity of thermal emittance to surface temperature. Any factor which causes a variation in surface temperature may thus be measured by thermography. Near-surface soil moisture is such a factor. Its presence causes large changes in the specific heat and thermal conductivity of the soil. Phase transformation of water during evaporation or freezing also have large thermal effects on the energy budget of land surface and thus affect the land-surface temperature. Complications with this method arise because soil temperature and surface emittance depend on a multitude of other physical factors. Plant growth, aspect of slope, water table, wind velocity and other variables alter soil temperatures and thermal emittance. The isolation of emittance variations caused by the presence of soil moisture is very difficult. Therefore, models describing emittance variations associated with various physical features must be developed to isolate their effects and to understand their interdependence. This may allow one to compensate for their effect during data analysis or to schedule the collection of data when their effect is small. In order to measure soil moistures over large areas using differences in thermal emittance, soil moisture must be measured at one reference site. If a model can e used to calculate the soil moisture difference between this site and a second site from the thermal emittance data, soil moisture can be calculated for this second site. This procedure can be repeated for any group of sites and thus a soil moisture map may be constructed. The general objective of this project was to develop and test a model which could be used in this manner to relate thermal emittance data to soil moisture.

Library of Congress Subject Headings

Soil moisture -- Measurement
Soil Moisture -- Mathematical models

Format

application/pdf

Number of Pages

84

Publisher

South Dakota State University

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