Document Type

Thesis - Open Access

Award Date

1982

Degree Name

Master of Science (MS)

Department / School

Physics

First Advisor

Jared A. Tunheim

Abstract

Thermal-infrared imagery (thermography) obtained from satellite altitudes has been shown to be a promising new tool for resource management and development. Satellite-borne thermal-infrared sensors allow the collection of time-sequential thermal-infrared radiation (thermal emittance) data over large land surface areas of the earth at relatively low cost. Thus, any resource which can be related to thermal emittance can be readily monitored. Thermal emittance from a surface is proportional to the fourth power of the surface temperature. Thus any factor which affects the surface temperature greatly affects the surface thermal emittance. · Moisture is such a factor when the land surface is considered. Near surface soil moisture changes the heat capacity and thermal conductivity of the soil and thus greatly alters the temperature of the land surface. Thermography is very sensitive to such changes in surface temperature making it a potentially useful tool for monitoring near surface soil moisture. Factors other than soil moisture also affect soil surface temperature and thus thermal emittance. These factors such as near surface ground water, wind velocity, topography of the land, plant canopy, soil type, and other variables serve to complicate the method. Thus, the isolation of one factor such as soil moisture and its effect on thermal emittance is difficult. Therefore, the interrelationship between these factors must be understood before a model that describes variations in thermal emittance can be constructed. The resource scientist may then be able either to compensate for the effect of these factors during data analysis or collect data when these factors have a minimal effect on the thermal emittance of the land-surface. The specific objectives of this research concerning the .testing and modification of the model for monitoring soil moisture were: 1. To investigate the relationship between soil surface temperature differences and soil moisture differences as predicted by the existing heat flow model. 2. To investigate the relationship between surface soil heat flux and calculated surface temperature differences predicted by the same existing theoretical model. 3. To modify the existing heat flow model to accept plant parameters as inputs. 4. To test the modified theoretical model by comparing predicted surface temperature differences with apparent temperature difference acquired experimentally over two plots with an oats crop canopy.

Library of Congress Subject Headings

Soil moisture -- Measurement
Soil temperature
Thermography

Format

application/pdf

Number of Pages

93

Publisher

South Dakota State University

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