Fate of river Tiber discharge investigated through numerical simulation and satellite monitoring

Ocean Science

F.Bignami¹  A.Orasi¹  R.Inghilesi¹  R.Santoleri¹  C.Pizzi¹  L.Ottolenghi¹ 

DOI  :  10.5194/os-8-773-2012

学科分类：海洋学与技术

来源: Copernicus Publications

【 摘 要 】

The aim of this study was to determine the dispersion of passive pollutantsassociated with the Tiber discharge into the Tyrrhenian Sea using numericalmarine dispersion models and satellite data. Numerical results obtained inthe simulation of realistic discharge episodes were compared with thecorresponding evolution of the spatial distributions of MODIS diffuse lightattenuation coefficient at 490 nm (K490), and the results were discussedwith reference to the local climate and the seasonal sub-regional circulationregime. The numerical model used for the simulation of the sub-tidalcirculation was a Mediterranean sub-regional scale implementation of thePrinceton Ocean Model (POM), nested in the large-scale MediterraneanForecasting System. The nesting method enabled the model to be applied toalmost every area in the Mediterranean Sea and also to be used in seasons forwhich imposing climatological boundary conditions would have beenquestionable. Dynamical effects on coastal circulation and on water densitydue to the Tiber discharge were additionally accounted for in theoceanographic model by implementing the river estuary as a point source of abuoyant jet. A Lagrangian particle dispersion model fed with the POM currentfields was then run in order to reproduce the effect of the turbulenttransport of passive tracers mixed in the plume with the coastal flow. Twosignificant episodes of river discharge in both winter and summer conditionswere discussed in this paper. It was found that the winter regime wascharacterized by the presence of a strong coastal jet flowing with theambient current. In summer the prevailing wind regime induced coastaldownwelling conditions, which tended to confine the riverine waters close tothe shore. In such conditions sudden wind reversals due to local weatherperturbations, causing moderate local upwelling, proved to be the only effective wayto disperse the tracers offshore, moving the plume from the coast anddetaching large pools of freshwater.

【 授权许可】

Unknown