Estimation of the Lagrangian structure function constant C0 from surface-layer wind data

D. Anfossi, G. Degrazia, E. Ferrero, S. E. Gryning, M. G. Morselli, S. Trini Castelli

Risultato della ricerca: Contributo su rivistaArticolo in rivistapeer review

Abstract

Eulerian turbulence observations, made in the surface layer under unstable conditions (z/L < 0), by a sonic anemometer were used to estimate the Lagrangian structure function constant C0. Two methods were considered. The first one makes use of a relationship, widely used in the Lagrangian stochastic dispersion models, relating C0 to the turbulent kinetic energy dissipation rate ε, wind velocity variance and Lagrangian decorrelation time. The second one employs a novel equation, connecting C0 to the constant of the second-order Eulerian structure function. Before estimating C0, the measurements were processed in order to discard non-stationary cases at least to a first approximation and cases in which local isotropy could not be assumed. The dissipation ε was estimated either from the best fit of the energy spectrum in the inertial subrange or from the best fit of the third-order longitudinal Eulerian structure function. The first method was preferred and applied to the subsequent part of the analysis. Both methods predict the partitioning of C0 in different spatial components as a consequence of the directional dependence of the Eulerian correlation functions due to the isotropy. The C0 values computed by both methods are presented and discussed. In conclusion, both methods provide realistic estimates of C0 that compare well with previous estimations reported in the literature, even if a preference is to be attributed to the second method.

Lingua originaleInglese
pagine (da-a)249-270
Numero di pagine22
RivistaBoundary-Layer Meteorology
Volume95
Numero di pubblicazione2
DOI
Stato di pubblicazionePubblicato - 2000

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