Preliminary Applications Of The ROMS Ecosystem Model To The Northern Adriatic Sea

Ilaria Iermano (1), Russo Aniello (1), Jacopo Chiggiato (2), Richard P. Signell (3)
(1) Department of Marine Sciences, Polytechnic University of Marche, Ancona, Italy
(2) Hydro-Meteorological Service, ARPA-SIM, Bologna, Italy
(3) U. S. Geological Survey, Woods Hole, MA, USA


The Adriatic Sea is a continental basin of the Mediterranean Sea, and its north-western part is particularly shallow and interested by large river runoff (Po is the main river, with an average runoff of 1500 m3 s-1). This portion of the Adriatic basin is interested by phenomena such eutrophication, mucilage, bottom waters anoxia, which have negative impacts on the environment, tourism and fisheries. Nevertheless the buoyancy gain due to the freshwater input, very dense waters (up to 30 in sigma-theta) may form in the northern Adriatic in winter thanks to the Bora wind blowing. The peculiarity of this area makes it a challenging one to model.
The Regional Ocean Modeling System (ROMS) has been already implemented in the Adriatic Sea during the 2002-03 Adriatic Circulation Experiment, and the operational version AdriaROMS is currently running. Considering the relevant environmental concerns about the northern Adriatic basin, the biogeochemical module of ROMS has been activated and realistic simulations are being conducted with it with the general aim of a better understanding of the Adriatic phenomenology. Some of the current specific objectives are evaluation of the model ability to provide short term forecast of hypoxic events and evaluation of the influence of nutrient input from different rivers.
The Fasham-type ecological model is a relatively simple representation of nitrogen cycling processes in the water column and organic matter remineralization at the water-sediment interface that explicitly accounts for sediment denitrification.
The minimum set of equations consists of a system of seven coupled partial differential equations that describe the dynamics of seven variables: nitrate NO3, ammonium NH4, small and large detritus SDet and LDet, phytoplankton Phy, zooplankton Zoo, and chlorophyll Chl. In current work carbon and oxygen options are defined too and the equations for C-related components (i.e. TIC, alkalinity, C content of small and large detritus) and for oxygen are solved additionally.
Model initialization is derived by field data collected during oceanographic cruises. As in AdriaROMS, the air-sea fluxes are interactively computed by LAMI (Local Area Model Italy) using the ROMS sea surface temperature.
The first simulations show interesting highlights about the coupled physical-biogeochemical Adriatic dynamics.