Recent Micrometeorological Studies of Sensible Heat Flux in the Plant-atmosphere System

For many years scientists working in fields related to micrometeorology have used the “Eddy Covariance (EC)” technique to study the transfer of water vapour, carbon dioxide and other greenhouse gases between plants, soils, bodies of water and the atmosphere at the boundary layer. This complex statistical technique uses high frequency measurements of the movement of air in the three dimensions along with the analysis of an air sample taken from the same position at the same time to determine the net exchange, or flux, of carbon dioxide, water vapour and sensible heat. Monitoring stations are typically installed above a canopy, field of crop or grassland, where some of the prerequisites of meaningful readings such as homogeneity of terrain can be attained. Acquisition and maintenance of the instrumentation required are expensive. Therefore, alternative methods are of interest and, if proven reliable, they may also be implemented to overcome routinely problems in direct measurements obtained by EC, such as gap filling.On the basis of recent literature, this paper reports the results of experiments carried out to evaluate the reliability of two alternative methods based on surface renewal analysis to estimate sensible heat flux.