Mesoscale, seasonal and interannual variability in the Mediterranean Sea using a numerical ocean model

2005 ◽  
Vol 66 (2-4) ◽  
pp. 321-340 ◽  
Author(s):  
Vicente Fernández ◽  
David E. Dietrich ◽  
Robert L. Haney ◽  
Joaquín Tintoré
Atmosphere ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 202 ◽  
Author(s):  
Antonio Ricchi ◽  
Mario Marcello Miglietta ◽  
Davide Bonaldo ◽  
Guido Cioni ◽  
Umberto Rizza ◽  
...  

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.


2015 ◽  
Vol 12 (17) ◽  
pp. 14941-14980 ◽  
Author(s):  
N. Mayot ◽  
F. D'Ortenzio ◽  
M. Ribera d'Alcalà ◽  
H. Lavigne ◽  
H. Claustre

Abstract. D'Ortenzio and Ribera d'Alcalà (2009, DR09 hereafter) divided the Mediterranean Sea into "bioregions" based on the climatological seasonality (phenology) of phytoplankton. Here we investigate the interannual variability of this bioregionalization. Using 16 years of available ocean color observations (i.e. SeaWiFS and MODIS), we analyzed the spatial distribution of the DR09 trophic regimes on an annual basis. Additionally, we identified new trophic regimes, with seasonal cycles of phytoplankton biomass different from the DR09 climatological description and named "Anomalous". Overall, the classification of the Mediterranean phytoplankton phenology proposed by DR09 (i.e. "No Bloom", "Intermittently", "Bloom" and "Coastal"), is confirmed to be representative of most of the Mediterranean phytoplankton phenologies. The mean spatial distribution of these trophic regimes (i.e. bioregions) over the 16 years studied is also similar to the one proposed by DR09. But at regional scale some annual differences, in their spatial distribution and in the emergence of "Anomalous" trophic regimes, were observed compared to the DR09 description. These dissimilarities with the DR09 study were related to interannual variability in the sub-basin forcing: winter deep convection events, frontal instabilities, inflow of Atlantic or Black Sea Waters and river run-off. The large assortment of phytoplankton phenologies identified in the Mediterranean Sea is thus verified at interannual level, confirming the "sentinel" role of this basin to detect the impact of climate changes on the pelagic environment.


2003 ◽  
Vol 21 (1) ◽  
pp. 267-280 ◽  
Author(s):  
S. Brenner

Abstract. As part of the Mediterranean Forecasting System Pilot Project (MFSPP) we have implemented a high-resolution (2 km horizontal grid, 30 sigma levels) version of the Princeton Ocean Model for the southeastern corner of the Mediterranean Sea. The domain extends 200 km offshore and includes the continental shelf and slope, and part of the open sea. The model is nested in an intermediate resolution (5.5 km grid) model that covers the entire Levantine, Ionian, and Aegean Sea. The nesting is one way so that velocity, temperature, and salinity along the boundaries are interpolated from the relevant intermediate model variables. An integral constraint is applied so that the net mass flux across the open boundaries is identical to the net flux in the intermediate model. The model is integrated for three perpetual years with surface forcing specified from monthly mean climatological wind stress and heat fluxes. The model is stable and spins up within the first year to produce a repeating seasonal cycle throughout the three-year integration period. While there is some internal variability evident in the results, it is clear that, due to the relatively small domain, the results are strongly influenced by the imposed lateral boundary conditions. The results closely follow the simulation of the intermediate model. The main improvement is in the simulation over the narrow shelf region, which is not adequately resolved by the coarser grid model. Comparisons with direct current measurements over the shelf and slope show reasonable agreement despite the limitations of the climatological forcing. The model correctly simulates the direction and the typical speeds of the flow over the shelf and slope, but has difficulty properly re-producing the seasonal cycle in the speed.Key words. Oceanography: general (continental shelf processes; numerical modelling; ocean prediction)


2020 ◽  
Author(s):  
Apostolia-Maria Mavropoulou ◽  
Vassilios Vervatis ◽  
Sarantis Sofianos

<p>The Mediterranean Sea is characterized by a combination of long-term trends and climatic shifts known in the literature as “transients”, that impact the biogeochemical processes.  We focus on the dissolved oxygen (DO) concentration, as it is an essential oceanic parameter for the marine ecosystem functioning. Dissolved oxygen distribution in the ocean interior is controlled by air-sea interaction processes, ocean circulation patterns, and biological effects. Understanding the related mechanisms and the variability of the above processes requires systematic oceanographic measurements over long periods and at high spatial resolution. Taking advantage of the Mediterranean monitoring systems, we can examine the sensitive physical and biogeochemical processes in the Mediterranean ecosystem. In this study, we investigate and combine all available data of temperature, salinity and dissolved oxygen over the period 1960-2011 (taking into consideration the scarcity of the available DO observations during the last years). In order to receive a direct and accurate evaluation of the interannual changes in the Mediterranean Sea, we constructed a gridded dataset interpolated into 1/8<sup>ο</sup> x 1/8<sup>ο</sup> grid using Data-Interpolating Variational Analysis (DIVA). At the surface layer, the solubility-driven changes determine the dissolved oxygen concentration. In deeper layers, the interannual variability is more related to dynamical processes that may involve dense-water convection, biological consumption or mixing, rather than temperature trends. The observed changes in minimum/maximum oxygen zones are mostly related to abrupt shifts. The attribution of the observed variability involves complex physical and biogeochemical processes as well as anthropogenic activities and requires further analysis using modeling techniques and available operational tools.</p>


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