Land-surface emissivity

Abstract

Land-surface temperature (LST) and land-surface emissivity (LSE) jointly determine the longwave radiation in land-surface radiation budgets and are the key input parameters in climatic, hydrological, ecological, and biogeochemical models. LSE is an intrinsic property of the surface determined by its physical state and composition and can be used for terrestrial and planetary geological studies, bedrock mapping, and resource exploration (Hook et al., 1992, Kirkland et al., 2002, Rowan et al., 2005, Vaughan et al., 2003). LSE can also be used as input data for accurate LST estimation (Li and Becker, 1993, Snyder et al., 1998). Remote sensing has the advantages of being macroscopic, dynamic, and fast, and is the only means to acquire LST and LSE at global and regional scales (Liang, 2004). The “Definitions” section provides the traditional definitions of LSE as well as several definitions for the LSE of heterogeneous and nonisothermal mixed pixels on remote-sensing pixel scales. The “Thermal-Infrared Radiative Transfer Theory” section illustrates the basic theory of thermal-infrared radiative transfer. The “Emissivity Measurement Methods” section presents the way to measure the LSE both in the laboratory and in the field. The “Deterministic Solutions for Emissivity” section introduces typical retrieval algorithms for spectral emissivity and broadband emissivity. The method on modeling LSE is provided in the “Emissivity Modeling” section. The “Emissivity Products” section lists the most frequently used spectral emissivity and broadband emissivity products. Finally, a short summary is provided in the “Concluding Remarks” section.