The analysis of energy and ozone flux data from the LANDES 94 experiment

Parametrisation of vertical fluxes of matter and energy at the biosphere-atmosphere interface requires precise measurements over different periods of the plant growth cycle. Accuracy is related to the validation of Tailor's hypothesis and the stationarity and homogeneity of the turbulent scales characteristic of transfers, To allow for systematisation of measurements, we present an approach for calculation of turbulent fluxes based on searching for data selection criteria (noise criterion, statistical validation of the wind vertical fluctuations criterion and stationarity criteria) thus enabling rejection of a certain number of samples. This approach was applied to calculate vertical flux of ozone at the vegetation-atmosphere interface of a coniferous forest in southwest France. Out of 1474 turbulent samples, 35% that did not comply with the basic assumptions for calculation of fluxes were rejected on the basis of the criteria. After application of the criteria, the variation of non-dimensionalised standard deviations for ozone in relation to the Monin-Obukhov stability criterion complied with the forecasts of the surface layer similarity theory. (C) 2000 Elsevier Science Ltd. All rights reserved.