Projects

The AOD group has taken part to two European projects. The ECAWOM project of the MAST (Marine Science and Technology) program and the STOWASUS-2100 project of the Environment and Climate program. The goal of ECAWOM (1994-1996) (European Coupled Atmosphere Ocean Model) has been the development of a regional coupled atmosphere-ocean model. The STOWASUS-2100 (1997-2000) (STOrms, WAves, SUrges Scenarios) has analyzed the effects of the doubled concentration of greenhouse gases on storms, ocean waves and coastal surges in the European Seas.

The AOD group has coordinated two Italian projects, both supported by CNR (Consiglio Nazionale delle Ricerche), MAAMMed (1997-98) and IAMMed (1999). MAAMMed (Modelli Accoppiati Atmosfera Mare nel Mediterraneo, Coupled Atmosphere Ocean Modeling in the Mediterranean sea) has carried out the implementation of a meteo-marine prediction model in the Mediterranean region. IAMMed (Interazione Atmosfera Mare nel Mediterraneo, Air-Sea Interaction in the Mediterranean Sea) has analyzed the air-sea fluxes derived from satellite observations and computed by model simulations and intercompared these two different fields.

Presently, the AOD group is taking part to two Italian Projects. The "Programma Ambiente Mediterraneo" (Mediterranean Environment Program) supported by MURST (Italian Ministry for the University and Scientific and Technologic Research) and coordinated by ENEA. The ASIMed project (Air-Sea Interaction in the Mediterranean Sea) supported by ASI (Italian Space Agency).

The AOD group acts as consultant for Italian agencies and companies: Particularly, a deterministic system for the prediction of the storm surge in the Northern Adriatic is being implemented for the town council of Venice.

The modeling activity of the AOD group is based on a set of models:
HYPSE (moovie), POM (moovie), WAM (moovie), and MIAO (moovie).
(click on acronym for the description of the model and view the animation of the model results).

HYPSE is a barotropic (2-dimensional) model in curvilinear coordinates, whose numeric is similar to the external mode of the well known POM coastal model, but it includes the sea level pressure and the astronomical tide forcing. The model uses a Arakawa C-grid, a leap frog time differencing scheme, but for the diffusion terms that is integrated using a forward scheme. A standard quadratic bottom friction term is adopted. HYPSE predicts the sea surface elevation resulting from the divergence of the horizontal transport. It is used for the simulation of the storm surge in the Adriatic Sea. The adjoint of HYPSE is presently been developed and it will be used for data assimilation studies.

The curvilinear grid used for the operational implementation of HYPSE in the Adriatic Sea.

The meteorological contribution to the surface elevation of the Adriatic Sea from 10th to 30th November 1996 computed by HYPSE using the wind and sea level pressure fields of ECMWF (click here or on the image to see the moovie).

The structure of the main semidiurnal tide M2 (left) and main diurnal tide (right) in the Adriatic Sea.

The original POM model has been developed at Princeton University( Blumberg A.F. and G.L.Mellor 1987). POM is an ocean circulation model, which solves the hydrostatic primitive equations, with a free surface, curvilinear horizontal coordinates, vertical sigma-coordinate, and a second order closure scheme for the computation of the vertical mixing. The model adopts a C-grid with leap-frog time differencing, but for the diffusion terms which are integrated using a forward scheme. The integration of the vertical diffusion is fully implicit. The equations are integrated with a time-split scheme, where the barotropic circulation (external mode) is integrated with a time step more than one order of magnitude smaller than the baroclinic component (internal mode). The version of POM used by the AOD group uses has been extensively rewritten and modular version of the model developed at Princeton, which, however does not modify the basic dynamics of the model.. The model describes the 3-d structure of the ocean circulation and of the temperature and salinity fields. It is used by the AOD group mainly for simulation of the circulation in the Adriatic and Mediterranean Sea.

POM Manual (pdf format)

POM Home Page

The WAM wave model (WAMDI group, 1987) solves the energy transfer equation for the wave spectrum. The equation describes the variation of the wave spectrum F in space and time due to the advection of energy and local interactions. The wave spectrum is locally modified by the input of energy from the wind, the redistribution of energy due to nonlinear interactions and energy dissipation due to wave breaking. These processes are represented by the source functions S_in , S_nl, and S_ds respectively. The energy propagation and the integration of the source function are treated numerically using different techniques. The advective term is integrated with a first order upwind scheme. The source function is integrated with an implicit. scheme that allows an integration time step greater than the dynamic adjustment time of the highest frequencies in the model prognostic range. AOD uses a fortran90 version of WAM, developed by G.Giuliani. In the standard implementazion, the wave spectrum is discretized using 12 directions and 25 frequencies extending from 0.041 to 0.42 Hz with a logarithmic increment f_n+1 = 1.1 f_n.

The evolution of the wave field in the Mediterranean Sea during November 2000 (click here or on the image to view the moovie).

The evolution of the wave field in the Mediterranean Sea during December 2000 (click here or on the image to view the moovie).

Links about WAM:
http://www.dkrz.de/forschung/reports/report4/wamh-1.html
http://www.ecmwf.int/research/ifsdocs/WAVES/Chap6_Software2.html
http://www.fnmoc.navy.mil/PUBLIC/WAM/wam_det.html
http://www.cineca.it/meteo/index2.html
http://atmoweb.pstabruzzo.it/wam/

The BOLAM model has been developed at ISAC-CNR of Bologna (Buzzi et al, 1994). It is a grid point, hydrostatic model in sigma coordinates, computing zonal and meridional wind components $u,v$, potential temperature theta, specific humidity h and surface pressure p_s. The physics of the model includes: parameterization of vertical diffusion in the planetary boundary layer depending on the Richardson number, dry adiabatic adjustment, soil water and energy balance (the sea surface temperature is prescribed), radiation, cloud effects, large scale precipitation, condensation, evaporation, moist convection, and a mycrophysics scheme with 5 water-species. A fourth order horizontal diffusion is added to the prognostic equations except in the tendency of surface pressure, while second order horizontal diffusion is applied to the divergence of the horizontal velocity. Vertical discretization is of the Lorentz type (vertical velocity is defined at intermediate levels between the levels of the prognostic variables) with a variable step which gives higher resolution near the surface and the tropopause. Horizontal discretization adopts the Arakawa C-grid. Time discretization is based on a two time-level scheme, with time split integration technique, forward for the horizontal diffusion terms, pseudo-implicit for the vertical diffusion, forward-backward for the gravity wave motion and advection terms.

A parallel version for QUADRICS has been developed in cooperation with ENEA and is used for operational prediction by Servizi Tecnici Nazionali (link). It also used for operational predictions by Servizio Agrometeo Regionale Sardegna (link), Centro Meteo-idrologico della regione Liguria (link), Natioanal Observatory of Athens(link). BOLAM has been extensively used during the MAP (link) campaign and in the series of intercomparison studies COMPARE I, II, III sponsored by WMO.

Links about BOLAM
http://www.cmirl.ge.infn.it/MAP/BOLAM/Bolamin.htm
http://www.cineca.it/editions/ssc97/html/tartagli.htm
http://www.map.ethz
http://www.isao.bo.cnr.it/~dinamica/MAP.html

MIAO is a tri-modular model (atmosphere+wave+ocean) of the coupled atmosphere-sea system (called MIAO, Model of Interacting Atmosphere and Ocean). The model structure consists of three modules:BOLAM, POM, and WAM. The BOLAM model (BOlogna Limited Area Model, Buzzi et al. 1993) is a complete meteorological, hydrostatic, grid-point model. The POM model (Princeton Ocean Model, Blumberg A.F. and G.L.Mellor 1987) is a hydrostatic, sigma-coordinate, ocean circulation model, which adopts a second order closure scheme for the computation of the vertical mixing. The WAM (WAve Model, The WAMDI Group 1988) model describes the evolution of the ocean wave spectrum.

The MIAO model computes the air-sea fluxes, accounting for the feedbacks of the sea on the atmosphere. In this coupled model the sea surface temperature computed by the ocean circulation component and the sea surface roughness computed by ocean wave component are used by atmospheric circulation component which, in turn, computes the surface fluxes of momentum, heat and moisture. The representation of the boundary layer in MIAO is based on the Monin-Obukhov theory, with an iterative solution on the equation relating the dynamical quantities at the lowest level of the atmospheric model to the Monin-Obukhov length and the SSR.

The model framework allows both one-way and two-way coupling. In a one-way coupled simulation there is no feedback of the wave and SST fields on the atmospheric circulation. The two-way coupling can be restricted to the wave feedback or to the SST feedback, separately.

Miao is used for regional climate and hindcast studies.

Click here to see a selection of fields computed by MIAO. The simulation covers the period 10th to 30th nov.1996. Top-panel: Sea Level Pressure and surface wind, bottom-left: Significant wave height, bottom-right: sea surface elevation.