Coastal ocean forecasting with an unstructured grid model in the southern Adriatic and northern Ionian seas

Abstract

Abstract. SANIFS (Southern Adriatic Northern Ionian coastal Forecasting System) is a coastal-ocean operational system based on the unstructured grid finite-element threedimensional hydrodynamic SHYFEM model, providing short-term forecasts. The operational chain is based on a downscaling approach starting from the large-scale system for the entire Mediterranean Basin (MFS, Mediterranean Forecasting System), which provides initial and boundary condition fields to the nested system.The model is configured to provide hydrodynamics and active tracer forecasts both in open ocean and coastal waters of southeastern Italy using a variable horizontal resolution from the open sea (3-4 km) to coastal areas (50-500 m).Given that the coastal fields are driven by a combination of both local (also known as coastal) and deep-ocean forcings propagating along the shelf, the performance of SAN-IFS was verified both in forecast and simulation mode, first (i) on the large and shelf-coastal scales by comparing with a large-scale survey CTD (conductivity-temperature-depth) in the Gulf of Taranto and then (ii) on the coastal-harbour scale (Mar Grande of Taranto) by comparison with CTD, ADCP (acoustic doppler current profiler) and tide gauge data.Sensitivity tests were performed on initialization conditions (mainly focused on spin-up procedures) and on surface boundary conditions by assessing the reliability of two alternative datasets at different horizontal resolution (12.5 and 6.5 km).The SANIFS forecasts at a lead time of 1 day were compared with the MFS forecasts, highlighting that SANIFS is able to retain the large-scale dynamics of MFS. The largescale dynamics of MFS are correctly propagated to the shelfcoastal scale, improving the forecast accuracy (+17 % for temperature and +6 % for salinity compared to MFS). Moreover, the added value of SANIFS was assessed on the coastalharbour scale, which is not covered by the coarse resolution of MFS, where the fields forecasted by SANIFS reproduced the observations well (temperature RMSE equal to 0.11 • C).Furthermore, SANIFS simulations were compared with hourly time series of temperature, sea level and velocity measured on the coastal-harbour scale, showing a good agreement. Simulations in the Gulf of Taranto described a circulation mainly characterized by an anticyclonic gyre with the presence of cyclonic vortexes in shelf-coastal areas. A surface water inflow from the open sea to Mar Grande characterizes the coastal-harbour scale.

Challenges for Sustained Observing and Forecasting Systems in the Mediterranean Sea

“…The southern Adriatic Sea and Northern Ionian Forecasting System (SANIFS, Federico et al, 2017) is an unstructured grid limited area forecasting system downscaling the CMEMS Med-MFC forecasts up to 10 m along the coasts and inside the harbors. SANIFS is based on a 3D finite element hydrodynamics model (Umgiesser et al, 2004) and it considers 91 vertical levels with a 2 m resolution to a 20 m depth, progressively decreasing the resolution near the bottom.…”

Response to Referee 1

“…ing use of high-resolution unstructured meshes (Ferrarin et al, 2018;Federico, 2017;CMEMS, 2017) which have yet to survive the various obstacles to properly represent coupling for each of the straits (not only Bosphorus and Black Sea but others), realistically accounting for fluxes variability between the various coastal and basin-scale elements.…”

A multi-service data management platform for scientific oceanographic products

“…Among the exposed services it is important to mention the THREDDS Data Server (TDS) (THREDDS, 2017), which represents a web server that provides metadata and data access for scientific datasets, using a variety of remote data access protocols. More in detail, it offers a set of services that allows users a direct access to data produced in the context of the TESSA project namely the output of the AFS (Adriatic Forecasting System) (Guarnieri et al, 2008;Oddo et al, 2005Oddo et al, , 2006, AIFS (Madec, 2008;Oddo et al, 2009) and SANIFS (Federico et al, 2017) sub-regional models. In particular, the THREDDS includes the WMS -Web Map Service (WMS, 2006) -for the dynamic generation of maps starting from geographically referenced data, the direct downloading using the HTTP protocol.…”

“…It relies on various forecast environmental fields which affect the vessel stability in order to ensure that the computed route does not result in an exposure to dynamical hazards. In this context, the developed platform faces the lack of an efficient dissemination of marine environmental data in order to support the situational sea awareness (SSA), which is strategically important for the maritime safety and security (Lecci et al, 2015). In fact, an updated situation awareness requires an advanced technological system to make data available for decision makers, improving the capacity of intervention and avoiding potential damages.…”