Assessing the impact of ocean circulation model resolution on optimal maritime routing in the Ligurian Sea using VISIR-2

Ocean currents play a key role in determining optimal maritime routes, particularly in regions characterized by complex mesoscale and coastal dynamics. This study assesses the sensitivity of weather routing to ocean model resolution by comparing optimal routing paths obtained with the VISIR-2 model [1] forced by ocean circulation models with different spatial resolution. The Bastia (Corsica)–Nice (France) route was selected as a representative ferry corridor in the Mediterranean Sea. The route crosses the Ligurian Sea, a region characterized by a strong boundary current and intense mesoscale activity, making it a suitable test case to assess the sensitivity of optimal ship routing to ocean current resolution. Optimal routes between the two ports are computed daily for one year using: (i) the 4.2 km resolution Copernicus Marine Environment Monitoring Service (CMEMS) Mediterranean reanalysis product  [2] (reference experiment), and (ii) a regional NEMO configuration at 2 km horizontal resolution covering the broader Lingurian Sea (high-resolution experiment). The simulated vessel is a Ro-Pax passenger ferry with an overall length of 125 m, whose propulsion characteristics and CO₂ emission model are derived from [3]. In both experiments, time-varying ocean currents are used by VISIR-2 to compute time-optimal and least-CO₂ trajectories under realistic vessel dynamics. Wave conditions are also accounted for using the CMEMS wave dataset [4]. The comparison focuses on route geometry, travel time, CO₂ emissions and seasonal variability. The analysis aims to assess how differences in ocean model resolution influence optimal maritime routing. 

 

References:

[1] Mannarini, G., Salinas, M. L., Carelli, L., Petacco, N., and Orović, J.: VISIR-2: ship weather routing in Python, Geosci. Model Dev., 17, 4355–4382, https://doi.org/10.5194/gmd-17-4355-2024, 2024.

[2] Mediterranean Sea Physics Reanalysis. E.U. Copernicus Marine Service Information (CMEMS). Marine Data Store (MDS). DOI: 10.25423/CMCC/MEDSEA_MULTIYEAR_PHY_006_004_E3R1 (Accessed on 13-01-2026)

[3] Mannarini, G.; Carelli, L.; Orović, J.; Martinkus, C.P.; Coppini, G.: Towards Least-CO2 Ferry Routes in the Adriatic Sea. J. Mar. Sci. Eng. 2021, 9, 115. https://doi.org/10.3390/jmse9020115 

[4] Mediterranean Sea Waves Reanalysis. E.U. Copernicus Marine Service Information (CMEMS). Marine Data Store (MDS). DOI: https://doi.org/10.48670/mds-00376 (Accessed on 13-01-2026)

Acknowledgement: This research has received funding from the European Union’s H2020 innovation programme under the Grant Agreement No. 101112752.