Boundary-Layer Meteorology

, Volume 3, Issue 1, pp 3–14 | Cite as

Estimating effective net radiation for a mountainous Watershed

  • D. Storr
Article

Abstract

Net radiation estimates are frequently required in watershed research, e.g., in calculating evapotranspiration and snowmelt. In mountainous areas, the effective net radiation, i.e., the horizontal projection of the flux through a surface parallel to the slope, is a more accurate measure of the available energy than that measured with a horizontal sensor. In a non-homogeneous area, however, a basin average of effective net radiation is difficult to estimate.

The annual curves for net and global solar radiation under clear skies at one point in the Marmot Creek Experimental Watershed in Alberta, Canada, show variations from 55 to 650 ly day-1 for net radiation, and from 100 to 760 ly day-1 for global radiation. A factor to convert measured net radiation at the point to a basin average of effective net radiation is obtained by comparing these curves with that for effective clear sky global radiation for the basin, and by considering the ratio of net to global radiation over the various types of vegetation in the basin. This conversion factor varies throughout the year with the elevation of the Sun and the basin albedo, ranging from a maximum of 1.27 in December to a minimum of 0.93 in April, and averaging 1.06 for the year.

Keywords

Mountainous Area Conversion Factor Global Radiation Global Solar Radiation Surface Parallel 

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References

  1. Budyko, M. I.: 1958,The Heat Balance of the Earth's Surface, English translation by U. S. Dept. of Commerce, Washington, D.C., pp. 35–37.Google Scholar
  2. Davies, J. A.: 1967, ‘A Note on the Relationship Between Net Radiation and Solar Radiation’,Quart. J. Roy. Meteor. Soc. 93, 109–115.Google Scholar
  3. Federer, C. A.: 1968, ‘Spatial Variation of Net Radiation, Albedo and Surface Temperature of Forests’,J. Appl. Meteor. 7, 789–95.Google Scholar
  4. Ferguson, H. L., Cork, H. F., Mastoris, S., Anderson, R., and Weisman, B.: 1971, ‘Theoretical Clear Sky Insolation in Marmot Creek Basin’,Canadian Meteorological Service, Climatological Studies, No.21, 45 pp.Google Scholar
  5. Geiger, R.: 1965,The Climate Near the Ground, English translation by Harvard Univ. Press, Cambridge, Mass., pp.5 and 15–18.Google Scholar
  6. Hay, J. E.: 1971, ‘Computation Model for Radiative Fluxes’,New Zealand J. Hydrol. 10, No. 1.Google Scholar
  7. Kirby, C. L. and Ogilvie, R. T.: 1969, ‘The Forests of Marmot Creek Watershed Research Basin’,Canadian Forestry Service Publication 1259, Department of Fisheries and Forestry, Ottawa, Ont.Google Scholar
  8. Kondrat'yev, K.: 1965,Radiative Heat Exchange in the Atmosphere, transl. from Russian, Pergamon Press, Oxford.Google Scholar
  9. Lee, R.: 1963, ‘Evaluation of Solar Beam Irradiation as a Climatic Parameter on Mountain Watersheds’,Hydrology papers, Colorado State University, Fort Collins, Colo.Google Scholar
  10. Ohmura, A.: 1968, ‘The Computation of Direct Insolation on a Slope’,Climatological Bulletin, No. 3, McGill University, Montreal, Que., 42–53.Google Scholar
  11. Polavarapu, R. J.: 1970, ‘A Comparative Study of Global and Net Radiation Measurements at Guelph, Ottawa, and Toronto’,J. Appl. Meteor. 9, 809–814.Google Scholar
  12. Rouse, W. R. and Wilson, R. G.: 1969, ‘Time and Space Variations in the Radiant Energy Fluxes over Sloping Forested Terrain and Their Influence on Seasonal Heat and Water Balances at a Middle Latitude Site’,Geografiska Annaler,51, Ser. A, 160–175.Google Scholar
  13. Shaw, R. H.: 1956, ‘A Comparison of Solar Radiation and Net Radiation’,Bull. Amer. Meteor. Soc. 37, 205–206.Google Scholar
  14. World Meteorological Organization: 1961,Guide to Meteorological Instrument and Observing Practices, W.M.O., No. 8 TP 3.Google Scholar

Copyright information

© D. Reidel Publishing Company 1972

Authors and Affiliations

  • D. Storr
    • 1
  1. 1.Canada Department of EnvironmentAtmospheric Environment ServiceCalgaryCanada

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