Developing a long-term, high-resolution, continental-scale, spatially distributed time-series of topographically corrected solar radiation
Date
2004
Authors
Hobbins, Michael T., author
RamÃrez, Jorge A., author
Brown, Thomas C., author
Colorado State University, publisher
Journal Title
Journal ISSN
Volume Title
Abstract
Our aim is to develop a long-term, high resolution net radiation data set that accounts for the effects of local topography that confound simpler analyses of the shortwave radiative balance in rugged terrain; such a dataset may then be used in direct observations of the effects of long-term change and variability in the solar radiation input to the land surface-atmosphere interface, particularly with reference to the estimation of evaporation. Direct and diffuse horizontal solar radiation data are gathered from all reporting stations across the conterminous United States for the period of 1950-1994 and integrated at a monthly time-step. Twelve years of diffuse horizontal radiation data missing from the data sources are replicated based on their historical relationships to coincident and contemporaneous observed direct normal and global radiation. A topographic correction factor is derived to account for the incidence of direct solar radiation on arbitrarily oriented surfaces at any latitude at any moment in any day of the year, and combined with slope and aspect surfaces for the conterminous U.S. derived from a 5-km digital elevation mode. This factor takes into account the solar geometry throughout the seasonal and diurnal cycles by incorporating an hourly weighting in proportion to the diffuse horizontal radiation recorded during the middle day of the month, and is then applied to spatially interpolated surfaces of direct solar radiation and combined with spatially interpolated surfaces of diffuse radiation. Summed, these provide the total incident solar radiation input to an existing energy budget analysis to yield the net surface radiation that may then be applied in models of evaporation. As preliminary uses of this dataset, mean annual and long-term trend surfaces of net surface radiation over the conterminous U.S. for the period WY 1953-1994 are presented.
Description
24th annual AGU hydrology days was held at Colorado State University on March 10-12, 2004.
Includes bibliographical references.
Includes bibliographical references.