arXiv subjects

Alberto Maurizi

Publications and source records attributed to Alberto Maurizi.

4 recordsLinked to original sources

arXiv2013

Some considerations on skewness and kurtosis of vertical velocity in the convective boundary layer

Data of skewness $S$ and kurtosis $K$ of vertical velocity in the convective boundary layer from different datasets have been analysed. Vertical profiles of $S$ were found to be grouped into two classes that display different slopes with height: one is nearly constant and the other is increasing. This behaviour can be explained using a simple model for the PDF of vertical velocity and assuming two distinct vertical profiles of updraft area fraction from literature. The possibility of describing the explicit dependence of $K$ on $S$ was revised critically, also considering the neutral limit as well as the limit for very small non-dimensional height. It was found that the coefficients of the relationship depends on both the Obukhov length scale $L$ and inversion height $z_i$.

physics.ao-ph↗

arXiv2013

Are Lagrangian stochastic models at odds with statistical theories of relative dispersion?

In an article on statistical modelling of turbulent relative dispersion, Franzese & Cassiani (2007, p. 402) commented on Lagrangian stochastic models and reported some concern about the consistency between statisti- cal and stochastic modelling of turbulent dispersion. In this short article, comparison of the two approaches is performed. As far as the dependence of models from turbulence constants is concerned, the two theoretical ap- proaches are found to be in perfect agreement eliminating every possible concern.

physics.flu-dyn↗

arXiv2005

On the dependence of third- and fourth-order moments on stability in the turbulent boundary layer

In this short review it is suggested that the relationship between third- and fourth-order moments of turbulence in the atmospheric boundary layer depends on stability. This can explain some differences among datasets, and provides a key point for modelling improvement.

physics.ao-ph↗

arXiv2003

Lagrangian turbulence in the Adriatic Sea as computed from drifter data: effects of inhomogeneity and nonstationarity

The properties of mesoscale Lagrangian turbulence in the Adriatic Sea are studied from a drifter data set spanning 1990-1999, focusing on the role of inhomogeneity and nonstationarity. A preliminary study is performed on the dependence of the turbulent velocity statistics on bin averaging, and a preferential bin scale of 0.25 is chosen. Comparison with independent estimates obtained using an optimized spline technique confirms this choice. Three main regions are identified where the velocity statistics are approximately homogeneous: the two boundary currents, West (East) Adriatic Current, WAC (EAC), and the southern central gyre, CG. The CG region is found to be characterized by symmetric probability density function of velocity, approximately exponential autocorrelations and well defined integral quantities such as di usivity and time scale. The boundary regions, instead, are significantly asymmetric with skewness indicating preferential events in the direction of the mean flow. The autocorrelation in the along mean flow direction is characterized by two time scales, with a secondary exponential with slow decay time of 11-12 days particularly evident in the EAC region. Seasonal partitioning of the data shows that this secondary scale is especially prominent in the summer-fall season. Possible physical explanations for the secondary scale are discussed in terms of low frequency fluctuations of forcings and in terms of mean flow curvature inducing fluctuations in the particle trajectories. Consequences of the results for transport modelling in the Adriatic Sea are discussed.

physics.ao-ph↗