Performance and uncertainty of the all-wave net radiation space-time integrators by treetops

Abstract

The quantification of electromagnetic energy exchanged between plants and their environment is important for ecophysiological studies. Measurement techniques have been developed for the determination of these changes in different spatial scales. In the literature are found some studies describing the use of devices carrying radiometers rotating around isolated trees. Otherwise, when it comes to plantations with spatial arrangement of trees in hedgerows, it is more convenient to use a notional cylindrical geometry of measurement. In this paper we described technical details of assembling devices moving along a stretch of the planting line, generating a notional cylindrical geometry for space-time integration of the all-wave radiation absorbed by the trees in hedgerow. Throughout the experiments it was verified the need for minor modifications which led to the improvement of mobile systems of measurement. Tests with the device free of plants indicated that the errors arising from the null deviation in this condition were sufficiently small. Analyses of measurements of each net radiometer over several days and, also comparison with measurement of daily latent heat calculated from sap flow in 24-hr period indicated that the proposed system gives accurate measurements, being reliable for testing the results of physical-mathematical models.