the Creative Commons Attribution 3.0 License. Nonlinear Processes in Geophysics Structure function analysis and intermittency in the atmospheric

Abstract. Data from the SABLES98 experimental campaign (Cuxart et al., 2000) have been used in order to study the relationship of the probability distribution of velocity incre-ments (PDFs) to the scale and the degree of stability. This connection is demonstrated by means of the velocity struc-ture functions and the PDFs of the velocity increments. Using the hypothesis of local similarity, so that the third order structure function scaling exponent is one, the inertial range in the Kolmogorov sense has been identified for dif-ferent conditions, obtaining the velocity structure function scaling exponents for several orders. The degree of intermit-tency in the energy cascade is measured through these expo-nents and compared with the forcing intermittency revealed through the evolution of flatness with scale. The role of non-homogeneity in the turbulence structure is further analysed using Extended Self Similarity (ESS). A criterion to identify the inertial range and to show the scale independence of the relative exponents is described. Finally, using least-squares fits, the values of some parameters have been obtained which are able to characterize intermittency according to different models