Theoretical Background of Thermal Infrared Remote Sensing

Abstract

Thermal infrared (TIR) data is acquired by a multitude of ground-based, airborne, and spaceborne remote sensing instruments. A broad variety of fields apply thermal infrared remote sensing, for example to assess general land- or sea-surface temperature dynamics, detect forest, coal and peat fires, map urban heat islands or thermal water pollution, differentiate geologic surfaces, analyze soil moisture, or even to test materials, to name only a few applications. As thermal infrared data has to be analyzed slightly differently than reflective data, this chapter contains the relevant theoretical background. The thermal domain of the electromagnetic spectrum, the laws of Planck, Stefan-Boltzmann, Wien, and Kirchhoff, as well as important parameters such as kinetic and radiance temperature, emissivity, and thermal inertia are briefly explained. The chapter thus provides readers with a common understanding before proceeding to subsequent chapters.