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

Parametrisation of vertical fluxes of matter and energy at the biosphere-at mosphere interface requires precise measurements over different periods of the plant growth cycle. Accuracy is related to the validation of Tailor's h ypothesis and the stationarity and homogeneity of the turbulent scales char acteristic of transfers, To allow for systematisation of measurements, we p resent an approach for calculation of turbulent fluxes based on searching f or data selection criteria (noise criterion, statistical validation of the wind vertical fluctuations criterion and stationarity criteria) thus enabli ng rejection of a certain number of samples. This approach was applied to c alculate 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 we re rejected on the basis of the criteria. After application of the criteria , the variation of non-dimensionalised standard deviations for ozone in rel ation to the Monin-Obukhov stability criterion complied with the forecasts of the surface layer similarity theory. (C) 2000 Elsevier Science Ltd. All rights reserved.