39 Surface Radiation Balance
Part 4. Hydrometeorology
Published Online: 15 APR 2006
Copyright © 2005 John Wiley & Sons, Ltd
Encyclopedia of Hydrological Sciences
How to Cite
Unsworth, M. H. 2006. Surface Radiation Balance. Encyclopedia of Hydrological Sciences. 4:39.
- Published Online: 15 APR 2006
The surface radiation balance is the algebraic sum of the net solar radiation and the net long-wave radiation received by a surface. It may be measured directly with a net radiometer, deduced from measurements of its upwelling and downwelling components, or modeled from climatological, geographical, and atmospheric data. Methods of modeling and measuring each of the components are discussed. Downwelling solar radiation from cloudless skies may be modeled from knowledge of atmospheric properties, but effects of clouds require more empirical approaches most suitable for monthly means. Downwelling long-wave radiation below cloudless skies is well related to temperature and humidity near the ground. An empirical method to account for clouds is given. Reflection coefficients and emissivities of natural surfaces are tabulated for use in calculating upwelling short and long-wave radiation. Net radiometer designs are reviewed, and examples are given of the surface radiation balance and its components over forest and grass. Issues of spatial variability of the surface radiation balance are discussed.
- solar radiation;
- long-wave radiation;
- reflection coefficient;
- net radiation