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ARS Home » Pacific West Area » Boise, Idaho » Northwest Watershed Research Center » Research » Publications at this Location » Publication #198375
Title: Scaling and parametrization of clear-sky solar radiation over complex topography

Author
item ESSERY, RICHARD - UNIV OF WALES, UK
item Marks, Daniel

Submitted to: Journal of Geophysical Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/28/2007
Publication Date: 5/26/2007
Citation: Essery. R., and Marks, D., (2007) Scaling and parametrization of clear-sky solar radiation over complex topography, Journal of Geophysical Research, Vol. 112, D10122.

Interpretive Summary: Solar radiation at the land surface is influenced by slope, aspect, shadows and obstruction of the sky, all of which vary over a wide range of length scales in regions of complex topography, with important consequences for the surface energy balance. Atmospheric models, however, generally assume the surface to be flat on subgrid scales. We test four areas in North America, ranging in latitude from 39±N to 69±N and in topography from rolling using actual topography to evaluate how these differ from the assumption of a flat region. For each region, we present the fraction of surface in shadow, the average and standard deviation of direct and diffuse irradiance to show the importance of representing actual topographic structure in large-scale models

Technical Abstract: Solar radiation at the land surface is influenced by slope, aspect, shadows and obstruction of the sky, all of which vary over a wide range of length scales in regions of complex topography, with important consequences for the surface energy balance. Atmospheric models, however, generally assume the surface to be flat on subgrid scales. For four areas in North America, ranging in latitude from 39±N to 69±N and in topography from rolling to mountainous, we simulate spatial patterns of clear-sky incoming solar radiation. Parametrizations are presented for fractions of the surface in shadow and averages, standard deviations and distributions of direct-beam and diffuse solar radiation, requiring only the standard deviation of slope as a topographic input. The scaling of this parameter with the resolution and extent of the underlying elevation grid and with the standard deviation of elevation is investigated.