Revista Brasileira de Engenharia Agrícola e Ambiental
versão On-line ISSN 1807-1929
ANGELOCCI, Luiz R. et al. Radiation balance of coffee hedgerows. Rev. bras. eng. agríc. ambient. [online]. 2008, vol.12, n.3, pp. 274-281. ISSN 1807-1929. http://dx.doi.org/10.1590/S1415-43662008000300008.
The radiation balance of hedgerows is an important variable in studies of mass and energy exchanges between parcial ground cover crops and the atmosphere. This paper describes a device with eight net radiometers encompassing the plants of a hedgerow. The radiometers were moved along a length of hedgerow, in a continuous and reversible movement. The canopy net radiation in this length (Rnc) was found by integration of the measurements over the notional cylinder formed. The device showed good performance and provided reliable measurements of Rnc of coffee hedgerows, showing itselfto be an useful technique of measurement in field conditions. Good correlations between Rnc and global solar radiation, turfgrass and coffee crop net radiation were found in 15-min, daytime and 24-hr periods, allowing the possibility of estimating Rnc from these simple measurements. Beers law was also used to have an independent estimation of Rnc. A good agreement was found between values of Rnc estimated by this law of attenuation and those integrated by the device in periods of 15 min, with overestimation of 10%, whereas for values integrated over daytime periods the agreement was not satisfactory.
Palavras-chave : correlation; instrumentation; solar radiation; net radiation.