Surface downward longwave radiation

Abstract

The energy balance of the Earth is a fundamental determinant of the climatic conditions on our planet. Surface downward longwave radiation is one of the four components required to calculate the Earth’s surface radiation budget, which is the key driving force for evapotranspiration. Regional and global surface longwave radiation budgets can be estimated only from satellite data that provide sufficient spatial and temporal sampling at a low cost and acceptable accuracy. This article focuses on the estimation of the surface downward longwave radiation (4-100 µm). Section “Background” is dedicated to the background and methods for estimating the surface downward longwave radiation. Section “Ground Measurements and Networks” briefly describes the field measurement instruments and the established flux networks that provide ground-measured components of surface longwave radiation budget. Section “Methods for Estimating Surface Downward Longwave Radiation” presents the methods for estimating the surface downward longwave radiation, including profile-based methods, parameterization methods, and hybrid methods. Section “Surface Longwave Radiation Budget Products” lists the existing surface longwave radiation budget products. A short summary is provided in section “Summary.”.