Multi-Physics Ensemble versus Atmosphere–Ocean Coupled Model Simulations for a Tropical-Like Cyclone in the Mediterranean Sea

Abstract

Between 19 and 22 January 2014, a baroclinic wave moving eastward from the Atlantic Ocean generated a cut-off low over the Strait of Gibraltar and was responsible for the subsequent intensification of an extra-tropical cyclone. This system exhibited tropical-like features in the following stages of its life cycle and remained active for approximately 80 h, moving along the Mediterranean Sea from west to east, eventually reaching the Adriatic Sea. Two different modeling approaches, which are comparable in terms of computational cost, are analyzed here to represent the cyclone evolution. First, a multi-physics ensemble using different microphysics and turbulence parameterization schemes available in the WRF (weather research and forecasting) model is employed. Second, the COAWST (coupled ocean–atmosphere wave sediment transport modeling system) suite, including WRF as an atmospheric model, ROMS (regional ocean modeling system) as an ocean model, and SWAN (simulating waves in nearshore) as a wave model, is used. The advantage of using a coupled modeling system is evaluated taking into account air–sea interaction processes at growing levels of complexity. First, a high-resolution sea surface temperature (SST) field, updated every 6 h, is used to force a WRF model stand-alone atmospheric simulation. Later, a two-way atmosphere–ocean coupled configuration is employed using COAWST, where SST is updated using consistent sea surface fluxes in the atmospheric and ocean models. Results show that a 1D ocean model is able to reproduce the evolution of the cyclone rather well, given a high-resolution initial SST field produced by ROMS after a long spin-up time. Additionally, coupled simulations reproduce more accurate (less intense) sea surface heat fluxes and a cyclone track and intensity, compared with a multi-physics ensemble of standalone atmospheric simulations.

Skill Assessment of an Atmosphere–Wave Regional Coupled Model over the East China Sea with a Focus on Typhoons

“…In contrast, there is overestimation of typhoon intensities by different high-resolution models [67]. To realistically simulate tropical cyclone intensity, we suggest implementing an atmosphere-wave-ocean coupled model system [68], and some key interaction processes, such as wave breaking-induced sea spray and wave breaking-induced mixing, should be considered [21].…”

Mediterranean Tropical-Like Cyclones (Medicanes)

“…In the last paper of the Special Issue, Ricchi et al [12] focused on the comparison of two different modeling approaches, comparable in terms of computational cost, to represent the evolution of a Medicane in the central Mediterranean. First, an ensemble of WRF model runs using different microphysics and turbulence parameterization schemes was considered; next, a two-way atmosphere-ocean coupled configuration using the COAWST modeling system was employed.…”

Impact of high-resolution sea surface temperature representation on the forecast of small Mediterranean catchments' hydrological responses to heavy precipitation

“…Furthermore, SST sensitivity is assessed in the context of the overall uncertainty linked to initial and boundary conditions in regional modelling, using different forcing GCMs, with and without data assimilation. To this aim, different accuracy levels of SST representation are used in an operational meteorological-hydrological forecasting chain over a coastal Mediterranean area including, in addition to the native SST fields of the general circulation models (GCMs), higher-resolution fields: the Medspiration level 4 ultra-highresolution foundation SST "SSTfnd" from the Medspiration project by the Centre European Remote Sensing d'Archivage et de Traitement (CERSAT) and the Institut Français de Recherche pour L'Exploitation de la Mer (IFREMER; Merchant et al, 2008;Robinson et al, 2012). Furthermore, two GCM forecasts are used, namely the global forecasting system (GFS) provided by the US National Weather Service (NWS) and the integrated forecasting system (IFS) developed at the European Centre for Medium-Range Weather Forecasts (ECMWF), as well as a three-dimensional variational assimilation (3D-Var) scheme.…”