Analysis and modeling of the radiation budget and net radiation of a sandhills wetland

Abstract

The surface radiation budget consists of the streams of incoming and outgoing shortwave and longwave radiation flux. Net radiation. the algebraic sum of these four terms, is very significant because it represents the amount of energy available to drive surface climatic, hydrologic, and biological processes. Heterogeneity of the surface is an important factor controlling the spatial variability of the radiation budget. Wetland surfaces such as those in the Nebraska Sandhills are a complex mosaic of cover types and surface conditions and, thus, have potential for great variability in their surface radiation and energy microclimate. In this study, radiation budget data collected using fixed measurement stations and mobile instruments were used to assess the degree and causes of variability in the radiation regime within a typical Sandhills wetland. The site was stratified into four subsystems, high and low marsh, subirrigated meadow, and open water. Results show that there is no significant variability of radiation regime within the marsh, but the marsh, meadow, and water are all separable from each other. Surface albedo appears, to be a significant factor separating the subsystems, while the longwave energy balance functions as an “homogenizing” influence. Further analysis indicates that accurate estimates of net radiation can be made using only measurements of solar radiation.