The radiation balance of a tropical pasture, I. The reflection of short-wave radiation

✍ Scribed by J.D. Kalma; R. Badham

• Publisher: Elsevier Science
• Year: 1972
• Weight: 470 KB
• Volume: 10
• Category: Article
• ISSN: 0002-1571
• DOI: 10.1016/0002-1571(72)90030-1

✦ Synopsis

Short-wave reflection (albedo) was measured for three agricultural surfaces at Katherine, N. T., Australia, between December 18, 1969 and March 28, 1970. The seasonal albedo value for the pasture legume Townsville stylo was 0.19, for a mixed stand of two annual grass species 0.22, and for bare soil 0.21. Albedo of dry soil varied between 0.20 and 0.22. Wetting could lower albedo to 0.14. Maximum albedos for TownsviUe stylo and grasses were 0.25 and 0.28. Minimum values (0.13 and 0.15, respectively) were found at plant establishment. Rapid increase in albedo was associated with periods of rapid g~owth (increasing crop cover and increasing leaf area index).

Severe water stress occurred after February 20 and albedo for both vegetative surfaces consequently decreased through reduction in effective crop cover, maturing of inflorescences and gradual senescence. Diurnal variation in albedo for all surfaces can partly be attributed to the sensors used, but part of the increase is due to the nature of the surfaces themselves. The role of specular reflection and internal trapping is discussed.