Historical Drifter Data and Statistical Prediction of Particle Motion: A Case Study in the Central Adriatic Sea

Abstract

In this paper, a method to analyze historical surface drifter data is presented that is aimed at investigating particle evolution as a function of initial conditions. Maps of drifter concentration at different times are built and interpreted as maps of the probability of finding a particle at a given time in the neighborhood of a given point in the domain. A case study is considered in a coastal area of the middle Adriatic Sea (a subbasin of the Mediterranean Sea) around the Gargano Cape, which is the focus of a newly planned experiment, the Dynamics of the Adriatic in Real Time (DART). A specific application is considered that seeks to improve the DART Lagrangian sampling planning.The results indicate that the analysis of historical drifters can provide very valuable information on statistical particle prediction to be used in experiment design. In the DART region, particle dynamics appear mostly controlled by the upstream properties of the boundary current as well as by the presence of a stagnation point located offshore of the tip of Gargano and separating two cross-basin recirculations. A significant seasonal dependence is observed, with drifters being more likely to leave the boundary current in winter and fall, when the current is wider and more connected to the cross-basin recirculations. Future developments are discussed, including joint analyses with numerical model results.

Variational analysis of drifter positions and model outputs for the reconstruction of surface currents in the central Adriatic during fall 2002

“…Here the EKE corresponds to the temporal variability of the currents over 45 d on a spatial scale equal to the model mesh size. In order to better characterize the field, also for the diagnostics introduced in the following sections, we further subdivide the WAC region in three regions (represented in Figure 2b), as by Veneziani et al [2007]. WAC1 and WAC2 are situated upstream the Gargano Cape, while WAC3 is downstream.…”

“…Mean flow after Veneziani et al [2007], obtained by averaging the historical drifter velocities over 0.1 degree square bins. The standard error ellipses are computed with respect to the major and minor axis of variability.…”

Transit and residence times in the Adriatic Sea surface as derived from drifter data and Lagrangian numerical simulations

“…Observations of ocean currents and dispersion with surface drifters have been used effectively to describe and quantify the transport characteristics from the global scale (Niiler et al, 2003) to marginal seas (Falco et al, 2000;Lacorata et al, 2001) and selected coastal areas (Haza et al, 2010;Veneziani et al, 2007, Choukroun et al, 2010. In particular, the Adriatic Sea, a semi-enclosed basin of the Mediterranean, connected to the Ionian Sea through the Otranto Channel (Fig.…”

“…Adriatic surface transport properties have been studied by Falco et al (2000). Relative dispersion as measured by drifters has been addressed by Lacorata et al (2001) and the statistical prediction of drifter 714 P.-M. Poulain and S. Hariri: Transit and residence times in the Adriatic Sea surface trajectories has been discussed by Castellari et al (2001) and Veneziani et al (2007).…”

On the response of a turbulent coastal buoyant current to wind events: the case of the Western Adriatic Current

“…Instabilities also surround the Gargano Promontory (Barale et al 1984). Furthermore, surface drifter data and satellite images have also revealed a recirculation region in its lee (Poulain 2001;Veneziani et al 2007;Burrage et al 2009). …”