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A fourth-order, fully two-way-coupled dual-domain Pacific Ocean Model (DUPOM) is developed to simulate the regional circulation in Asian Marginal Seas based on the whole North Pacific Ocean simulation framework. The model uses 1/4° and 1/8° horizontal resolutions for the eastern and western Pacific Ocean domains, respectively. The fully two-way-coupled approach shows seamless coupling behavior without any sponge layer. We validate the Kuroshio Current System and the regional circulation in the Asian Marginal Sea, including circulation patterns, volume transport variation and vertical current structure across several cross-sections. A single strong current core exists east of Taiwan and extends to the East China Sea. A cold dome near the northeast of Taiwan is a semi-permanent feature in the model results as observed. South of Japan (e.g. PCM5 line), the Kuroshio shows strong transport along the coast with a countercurrent offshore, reflecting a recirculation gyre. The transient of the three typical paths of the Kuroshio meander is also studied. Our results suggest that the path variation, particularly the Large Meander path, may be triggered by the baroclinic instability associated with westward propagating eddies.

The conveyor of the source water that feeds into the Taiwan Strait (TS), particularly from the south, is investigated using historical CTD (Conductivity-Temperature-Depth) data and a North Pacific Ocean and East Asian seas coupled model. The modeled currents and drifter trajectories suggest that the Kuroshio Branch Water (KBW) rarely flows directly into the TS from the Luzon Strait (LS) in winter; instead the massive westward movement of the Kuroshio conveys high salinity water to the southeastern TS through a loop-like route. In summer, the modeled flow fields suggest that the Kuroshio surface currents hardly intrude into the TS directly from the LS. Observations and model results show that the monsoon-driven northeastwardflowing currents in the northern South China Sea transport relatively low salinity water through the entire TS.

The impacts of global warming on the environment, economy and society are presently receiving much attention by the international community. However, the extent to which anthropogenic factors are the main cause of global warming is still being debated. There are obviously large stakes associated with the validity of any theory since that will indicate what actions need to be taken to protect the human race’s only home—Earth. Most studies of global warming have investigated the rates and quantities of carbon dioxide emitted into the atmosphere since the beginning of the industrial revolution. In this paper, we focus on the earth’s carbon budget and the associated energy transfer between various components of the climate system. This research invokes some new concepts: (i) certain biochemical processes which strongly interact with geophysical processes in climate system; (ii) a hypothesis that internal processes in the oceans rather than in the atmosphere are at the center of global warming; (iii) chemical energy stored in biochemical processes can significantly affect ocean dynamics and therefore the climate system. Based on those concepts, we propose a new hypothesis for global warming. We also propose a revolutionary strategy to deal with global climate change and provide domestic energy security at the same time. Recent ocean exploration indicates that huge deposits of oceanic methane hydrate deposits exist on the seafloor on continental margins. Methane hydrate transforms into water and methane gas when it dissociates. So, this potentially could provide the United States with energy security if the technology for mining in the 200-mile EEZ is developed and is economically viable. Furthermore, methane hydrate is a relatively environmentally benign, clean fuel. Such technology would help industry reduce carbon dioxide emissions to the atmosphere, and thus reduce global warming by harnessing the energy from the deep sea.

The DieCAST ocean model is applied to a study of the circulation in the Black Sea, using 1/12° horizontal resolution and with 20 vertical layers. Boundary forcings are monthly wind stress, evaporation minus precipitation, air–sea heat flux, freshwater influx from 11 rivers and exchange with the Mediterranean Sea through the Bosphorus Strait. The model reproduces fundamental physical features of the Black Sea: seasonal fluctuations in the quasi-permanent cyclonic Rim Current, numerous anticyclonic meanders and eddies lying between the Rim Current and the coast, Rossby waves propagating westward across the basin, coastally trapped waves, and the annual cycle of vertical mixing. Model results shed light on the mechanisms affecting such features. These include interactions of the Rim Current with coastal bathymetry abutments, leading to recirculations that pinch off vortices as in island wakes, and possible baroclinic instability of the Rim Current; these are modulated by the large annual stratification cycle above a relatively shallow and strong pycnocline, as is the Rim Current itself. The resulting wake eddies often merge into major coastal circulation features such as the seasonal Batumi and Sevastopol eddies. These anticyclonic eddies play a fundamental role in coastal and open-sea exchange processes. Hydrographic data from sampling cruises and recent Topex–Poseiden (T/P) altimeter data strongly supports our analysis.

Low-pass-filtered velocities obtained from surface drifters and surface geostrophic velocities estimated from TOPEX/Poseidon altimeter data have recently revealed a clear and robust seasonal cycle in the surface eddy kinetic energy (EKE) in the California Current (CC) [Kelly et al., 1998; Strub and James, 2000]. The seasonal cycle begins in spring when a surface-intensified baroclinic equatorward jet develops next to the coast in response to strong upwelling favorable winds. This jet, and a developing eddy field, then moves offshore during summer and fall. The EKE maximum associated with the jet progresses only as far as 127°W, beyond which it decreases rapidly. This is a robust characteristic of the seasonal cycle that has been previously attributed only to an unspecified dissipation process. To investigate this aspect of the surface EKE, a multiyear simulation of the CC is carried out using the Dietrich/Center for Air-Sea Technology primitive equation regional ocean model [Dietrich, 1997]. The simulation accurately reproduces many aspects of the observed annual cycle, including the offshore propagation of the EKE at the surface. The model results indicate that the decrease of surface EKE west of 127°W in the simulation is not due to dissipation but rather is caused by the vertical redistribution of EKE to the deep ocean. This redistribution occurs through the transformation of kinetic energy from the vertical shear flow to the vertical mean flow. The transformation is a nonlinear process inherently associated with the life cycle of baroclinically unstable waves, and in the CC, it effectively energizes the deeper ocean at the expense of the upper ocean. The process is also known to be important in the atmosphere [Wiin-Nielsen, 1962]. Taken together, the recent California Current observations and the new model results strongly suggest that the CC regularly supplies EKE to the deep waters of the eastern North Pacific.

The surface waters of Doubtful Sound, a glacially carved fjord in south-western New Zealand, feature a quasi-permanent low-salinity-layer (LSL). The LSL is maintained year round by the extreme precipitation in the catchment (∼7 m yr −1 ) and discharge from a hydroelectric power station (∼450 m 3 s −1 ). The robust, stable LSL has been shown to play a major role in controlling intertidal and subtidal community structure. By contrast, little is known about the dynamics of the LSL itself. The work presented here elucidates the response of the LSL to perturbations in the wind stress and rainfall. Frequency-domain analysis of salinity data collected from an array of moored instruments revealed that the LSL responded to perturbations in both the winds and rainfall. However, the specific roles of the wind stress and rain could not be adequately resolved in these analyses. By contrast, simulations of the response of the LSL using a three-dimensional primitive equation model revealed that strong up-fjord directed wind events set up a storm surge at the head of the fjord. This surge significantly deepens the LSL at the head of the fjord and retards or reverses estuarine circulation. The subsequent relaxation of the surge after the abatement of the wind stress resulted in a redistribution of buoyancy throughout the fjord over a two-day period. It is shown that the development and relaxation of the storm surge is a major process controlling the maintenance of the near-surface stratification.

The results of an intercomparison experiment performed with five numerical ocean models of different architecture are presented. While all models are able to simulate the large-scale characteristics of the North Atlantic circulation with a fair degree of realism, they also exhibit differences that can be attributed to the choices made in vertical coordinates, domain size, and boundary conditions.

The development and verification of a new version of the DieCAST ocean circulation model to be referred to as CANDIE (Canadian Diecast) are considered. Both CANDIE and DieCAST have many features in common with the well-known Modular Ocean Model (MOM) of the Geophysical Fluid Dynamics Laboratory. Of particular relevance to the present study are the rigid-lid approximation and the use of standard Cartesian coordinates. The DieCAST formulation in terms of the surface pressure, rather than the volume transport streamfunction, is also used in CANDIE to reduce numerical sensitivity to ocean depth variations. The major difference between MOM and DieCAST is the use of a mixed C and A grid formulation in DieCAST rather than the B grid formulation used in MOM. CANDIE differs from DieCAST in the use of a standard C grid formulation and a reduction in the magnitude of the time truncation error associated with the implicit treatment of the Coriolis force. The implementation of the rigid-lid approximation is r...

We describe a simple, flux conserving robust advection scheme that reduces numerical dispersion in application to passive scalar advection. Our hydrostatic semi-collocated (modified Arakawa ‘a’ grid) ocean model performance is enhanced by this modification in combination with a modified strategy for incompressibility. The modified advection scheme also reduces overshooting errors resulting from numerical dispersion in the evolution of a sloshing front using a non-hydrostatic model. In Gulf of Mexico simulations, many of the realistic detailed features from our original model using 1/12° (about 9 km) resolution occur using the modified numerics with 20-km resolution. These are not seen with the original numerics and 20-km resolution. These detailed features include: strong fronts and frontal eddies; many cyclonic eddies, which spin off major warm core Loop Current eddies; and sharp eastward deflection of the Loop Current directly into the Florida Strait after major warm core eddy shedding.

The Gulf of Mexico (GOM) circulation is simulated using the DieCAST ocean model, with a horizontal resolution of 1/12° and 20 vertical layers. The results compare well with observations of both large and small scale features, including Loop Current frontal occlusions associated with frontal eddies. The simulation is carried out without any data assimilation. The frontal eddies tend to be spaced at about 90° intervals around the Loop Current, leading to a Loop Current head shaped like a square with rounded corners. The pattern rotates as the eddies circle the Loop, and frontal eddies elongate as they squeeze through the Florida Strait. Major warm core eddies separate regularly from the Loop Current and propagate to the western GOM. Old warm core eddies in the western Gulf dissipate through bottom drag effects, which also generate cyclonic parasitic eddies. Newly arrived warm core eddies merge with old ones in the western GOM. Recently separated elongated Loop Current eddies can rotate and reattach temporarily to the Loop Current. The barotropic flow component develops eddies between the main separated warm core eddy and the Loop Current due to eastward dispersion, as the main eddy itself propagates westward into the Gulf.

Two and three-dimensional oceanic flows around small islands patterned after Barbados, W.I. (13° 10′ N latitude: 59° 30′ W longitude) were modeled numerically to investigate island wake effects. The two-dimensional simulations closely agreed with laboratory flows, for both attached and shedding wake regimes. As expected, results for a flat bottom confirmed that the Coriolis terms strongly affect pressure but not the flow. For idealized, yet typical incident flow speeds, water column stratification, island topography and appropriate Coriolis terms, three-dimensional simulations readily produced elongated wake patterns, dominated by surface intensified von Karman-like vortices. Effects of grid resolution, viscosity, bathymetry, and Coriolis forces on wake characteristics were studied. For islands with typical bottom slopes, realistically small horizontal eddy diffusivity has a minor effect compared to bottom drag in generating vorticity. Near-shore bathymetry (viz., the absence or presence of a con...

In application to the Gulf of Mexico (GOM), a new DieCAST ocean model, which uses a modified Arakawa ‘a’ grid, and the SOMS model, which uses an Arakawa ‘c’ grid, give remarkably similar results. The new model avoids ‘null space’ problems of the standard ‘a’ grid approach by first using fourth-order interpolations to a ‘c’ grid advection velocity, then applying incompressibility to the result. Accuracy is further improved by using fourth-order pressure gradient approximations at ‘a’ grid locations. Incompressibility with general geometry is satisfied efficiently by a fast-converging iteration with a regular gteometry elliptic solver. Results are compared with satellite-measured r.m.s. sea surface elevation anomaly and detailed front structures, climatological mean thermocline and empirical orthogonal functions and other observations.

We use a 2-dimensional non-hydrostatic model on the vertical plane to examine the nature of convective adjustment. In the first part of the study, we investigate the mixing of an initial unstably stratified 2-layer fluid with molecular viscosities. The linear growth rates compare well to those obtained using an analytic model. The stratification of the convectively adjusted state is sensitive to the Prandtl number (Pr, the ratio of the eddy viscosity to thermal diffusivity). This is important as the instantaneous convective adjustment used in coarse resolution ocean circulation models corresponds to Pr→0, while the case of immiscible fluids corresponds to the limit of large Pr. Mixing in the ocean as well as in our numerical model are both characterized by a finite value of Pr. In the second part of the study, we scale up to ocean scales with a more realistic surface forcing and turbulent viscosities. The implications of our results for instantaneous convective adjustment are discussed.

A numerical procedure for the analysis of the stresses due to rotation that are produced in disks of a general, arbitrary configuration is presented in this paper. The governing equilibrium equations and the constitutive relations for the rotating disk element are written in terms of the radial stress. A numerical simulation is performed based on repeated applications of a truncated Taylor's expansion to advance along the radius of the deformed disk. The treatment of both initial value problems and two point boundary value problems is presented based on a corresponding iterative root finding method. Examples for various disk geometries, including disks of constant thickness, linearly tapered thickness, and hyperbolic variation of thickness, respectively, are provided. Both radial as well as circumferential stresses are obtained and compared with existing analytical solutions to validate the present formulations. Particular consideration is given to the industrial example of turbine rotors carrying buckets. The simple procedure developed in this study may serve as an effective tool for performing preliminary design calculations for complex rotating components.

A two-dimensional non-hydrostatic ocean model and a hydrostatic version of the same modelare used to simulate convective adjustment, without the use of an instantaneous adjustmentparameterization. The model geometry is a domain on the vertical plane of width 40 km anddepth 500 m. Model results for four cases are examined: hydrostatic and non-hydrostatic, at0.1 and 1 km spatial resolution. The convectively adjusted stable state obtained in all four casesare qualitatively similar; thus the hydrostatic approximation does not eliminate convectiveadjustment. The details of the simulated convective plumes depend on resolution and whetherthe hydrostatic approximation is made. The adjusted state has significant stratification whichcannot be captured by the conventional instantaneous adjustment or diffusion-based parameterizations.We also compare the results to the case when an instantaneous adjustmentparameterization is used. DOI: 10.1034/j.1600-0870.2002.00162.x

New, fourth‐order “c” grid Coriolis term treatments are compared with widely used second‐order treatments. Their improved accuracy is demonstrated by a grid convergence study for a relevant linear problem. Such an accuracy improvement is relatively easy and costs little for low Rossby number flows compared with high Rossby number flows, because one must consider only the Coriolis and pressure gradient terms in low Rossby number flows. The “c” grid is favourable for the latter, but the Coriolis terms benefit greatly by the higher order treatments analysed herein.

The coupled DieCAST-SSBOM (Shirshov-Stony Brook Oil spill transport Model) circulation-oil spill transport model is used to predict the transport and dispersal of contaminants resulting from representative hypothetical oil spills in the Black Sea. With climatological forcing, the DieCAST model realistically simulates many of the dominant mesoscale features of seasonally-varying large scale circulation and meso-scale features of the circulation including the Rim Current, anticyclonic coastal eddies, headland eddy shedding and vertical stratification. The oil spill model ingests DieCAST surface currents and employs a Lagrangian tracking algorithm to predict the motion of a large number of seeded particles, the sum of which (~1 million) form the oil plume. Basic processes affecting the transport of oil and its fate (advection, sinking, evaporation, etc.) are included as parameters. Various scenarios of hypothetical blowouts of oil in different regions of the sea are simulated and discussed as to their structure, transport and likelihood of coastal contamination. The ultimate objective is to develop an operational oil slick model forced with synoptic winds and air-sea interaction.

An ocean response to typhoon Kai-Tak is simulated using an accurate fourth-order, basin-scale ocean model. The surface winds of typhoon Kai-Tak were obtained from QuikSCAT satellite images blended with the ECMWF wind fields. An intense nonlinear mesoscale eddy is generated in the northeast South China Sea (SCS) with a Rossby number of O (1) and on a 50-100 km horizontal scale. Inertial oscillation is clearly observed. Advection dominates as a strong wind shear drives the mixed layer flows outward, away from the typhoon center, thus forcing upwelling from deep levels with a high upwelling velocity (＞ 30m day^(-1)). A drop in sea surface temperature (SST) of more than 9℃ is found in both observation and simulation. We attribute this significant SST drop to the influence of the slow moving typhoon, initial stratification and bathymetry-induced upwelling in the northeast of the SCS where the typhoon hovered.

[1] A z-level, 4th-order-accurate ocean model is applied in six two-way-coupled grids spanning the Mediterranean Sea and North Atlantic Ocean (MEDiNA). Resolutions vary from 1/4° in central North Atlantic to 1/24° in Strait of Gibraltar region. This allows the MEDiNA model to efficiently resolve small features (e.g., Strait of Gibraltar) in a multibasin, multiscale model. Such small features affect all scales because of nonlinearity and low dissipation. The grid coupling using one coarse grid overlap is nearly seamless without intergrid sponge layers. No instant convective adjustment or other highly diffusive process is used. The deep water in the 1/8° Mediterranean Sea grid is formed by the resolved flows that emulate subgrid-scale processes directly. Downslope migration of Mediterranean Overflow Water (MOW) water involves dense water flowing away from the bottom laterally over bottom stairsteps in the z-level model, thus flowing over less dense underlying water. Without excessively water mass-diluting process, the advection dominates the downslope migration of thin, dense MOW in the simulation. The model results show realistic MOW migration to the observed equilibrium depth, followed by lateral spreading near that depth. The results are also consistent with the climatology along 43°N, where the MOW hugs a steep shelfslope centered at ∼1 km depth and then spreads westward, with the salinity core (S > 35.7) reaching 18°W. This study clearly restores z-level models to a competitive status doing density current simulations.

Five numerical schemes are compared using convergence studies in the framework of the hydrostatic Sandia Ocean Modeling System (SOMS). Three resolutions are used, 40, 20 and 10 km, with respectively three, seven and 15 layers and time steps of 60, 30 and 15 min, so 15 convergence calculations are performed. The same geophysical prototype problem (exhibiting baroclinic instability in a statically stable environment) is used for all calculations. All five schemes are second-order-accurate in space, but those using four-point interpolations for the Coriolis and pressure gradient terms are shown to produce much more accurate results, with relatively little extra computation, than schemes using two-point interpolations. Convergence is also indicated with decreasing horizontal diffusivities of 107, 106, and 105 cm2s−1. Using 107 cm2s−1 diffusivities causes substantial damping of the dominant instabilities during the 30-day integrations performed, but using 106 cm2 s−1 results in little damping and yields results very close to those using 105 cm2 s−1. A barotropic (vertically averaged flow) cyclonic northern basin gyre is explained as a weakly forced circulation. Its equilibrium amplitude is determined by a balance between dissipation effects due to horizontal mixing and diffusion, and weak second-order driving associated with thermodynamic forcing and vorticity dissipation at the basin bottom. It is thus quite sensitive to model dissipation but can be well described by SOMS owing to SOMS' low numerical dissipation.

The aspiration of spherical particles which are suspended without sedimentation in an ideal fluid that flows past a thin-walled sampler is investigated. A recent experimental study showed that secondary aspiration caused by particles bouncing off the walls of the nozzle and subsequently entering the nozzle inlet is of importance in determining the aspiration efficiency of samplers in many situations. Therefore the extent of oversampling caused by particle rebound is investigated using a numerical method. Three situations are considered, namely, when the particles (1) adhere to the sampler surface on impact, (2) bounce off the surface and all those that hit within a certain area, known as the stagnation area, are eventually sampled, and (3) bounce off the surface with no loss of energy. Results for the three cases are compared and they are found to display the same trends as found in the experimental investigations.

Guidelines are presented for efficient design and application of opposed swirl internal mix nozzles. Associated fluid dynamic mechanisms are briefly discussed.

[1] This paper presents simulations of the Adriatic Sea using the DieCAST model applied on a 1.2–min grid (about 2–km resolution). The simulations resolve the mesoscale variability because the grid size falls below the first baroclinic deformation radius (about 5–10 km) and DieCAST has very low horizontal dissipation. The model is initialized with seasonally averaged temperature and salinity data and forced with climatological winds and surface buoyancy fluxes (both heat flux and evaporation minus precipitation). River discharges are varied daily according to a perpetual year for every river, and the open-boundary conditions at Otranto Strait are obtained by nesting in two larger-scale models. The present simulations demonstrate that the DieCAST model allows mesoscale instabilities to develop at length scales of 5–20 km and over time scales of a few days. The simulated variability exhibits pronounced similarities with the actual mesoscale variability, in terms of location, nature and temporal evolution of the features. Meanders, swirls and eddies are noted along the relatively smooth Italian coast while offshore jets and filaments better describe the mesoscale activity along the more rugged coast of Croatia. In sum, DieCAST is highly suitable for the study of mesoscale variability in the Adriatic Sea. The present simulations also show that the seasonal hydrography of the Adriatic Sea is intrinsically unstable to mesoscale perturbations, and that the mesoscale variability along the Italian coast is the result of baroclinic instability of the Western Adriatic Current. It is shown how the properties of this instability are related to the local bottom topography.

In this paper, we present the results from a 1/8° horizontal resolution numerical simulation of the Mediterranean Sea using an ocean model (DieCAST) that is stable with low general dissipation and that uses accurate control volume fourth-order numerics with reduced numerical dispersion. The ocean model is forced using climatological monthly mean winds and relaxation towards monthly climatological surface temperature and salinity. The variability of the circulation obtained is assessed by computing the volume transport through certain sections and straits where comparison with observations is possible. The seasonal variability of certain currents is reproduced in the model simulations. More important, an interannual variability, manifested by changes in currents and water mass properties, is also found in the results. This may indicate that the oceanic internal variability (not depending on external atmospheric forcing), is an important component of the total variability of the Mediterranean circulation; variability that seems to be very significant and well documented by in situ and satellite data recovered in the Mediterranean Sea during the last decade. © 2005 Elsevier Ltd. All rights reserved., This study is a contribution to the Projects MAR1998-0840 and REN2001-3982. Partial support from SOFT, EC funded project, EVK3-2000-00561 is also acknowledged. V. Fernández acknowledges a FPI grant from the Spanish Ministry for Science and Technology (PN1998 36125588). David E. Dietrich acknowledges a grant from the Spanish ministry for Education and Culture (SAB1999-0037)

[1] Ocean circulation off the west coast of the United States is driven by a variety of mechanisms, the most important of which are the seasonally varying local wind stress and coastal irregularities. Remote forcing is also important and expressed through the open boundary conditions. We use a nonhydrostatic, Dietrich/Center for Air-Sea Technology (DieCAST) ocean model to simulate the regional circulation in the vicinity of Monterey Bay, California. Satellite images often show a cyclonic eddy in the bay and an anticyclonic eddy outside the bay during spring and summer. We compare the simulation results with observed mooring and HF radar-derived velocity data. The coastal geometry plays an important role in the generation and movement of coastal eddies. Quantitative comparisons between hydrostatic and nonhydrostatic models are made to investigate the importance of the nonhydrostatic effects in coastal ocean simulation. The results show that both the Sur Ridge area and the Monterey Submarine Canyon contribute significantly to nonhydrostatic effects and small-scale features. The strong nonhydrostatic and small-scale features result from the California Undercurrent flows across sloping bathymetry and interactions with near-surface California Current in summer. Rapid changes in slope in the presence of strong flows cause vertical acceleration, which violates the hydrostatic approximation. Surface-trapped nonhydrostatic fronts also occur frequently in the shallow ocean during winter. These effects have seasonal variation and cannot be ignored in coastal ocean modeling with complex bathymetry.

[1] Numerical experiments varying lateral viscosity and diffusivity between 20 and 150 m2/s in a North Atlantic Ocean (NAO) model having 4th-order accurate numerics, in which the dense deep current system (DCS) from the northern seas and Arctic Ocean is simulated directly show that Gulf Stream (GS) separation is strongly affected by the dissipation of the DCS. This is true even though the separation is highly inertial with large Reynolds number for GS separation flow scales. We show that realistic NAO modeling requires less than 150 m2/s viscosity and diffusivity in order to maintain the DCS material current with enough intensity to get realistic GS separation near Cape Hatteras (CH). This also demands accurate, low dissipation numerics, because of the long transit time (1–10 years) of DCS material from its northern seas and Arctic Ocean source regions to the Cape Hatteras region and the small lateral and vertical scales of DCS.

A new model-based method of determining the surface fluxes of heat and freshwater that are needed to force ocean models is presented. In contrast to deriving the fluxes from a simulation with a restoring surface boundary condition, the new method determines the fluxes as a residual within the framework of physically realistic and natural boundary conditions on the sea surface temperature (SST) and sea surface salinity (SSS). The fluxes are computed (diagnosed) in such a way that an ensemble average of the model-simulated annual cycles of SST and SSS match the observed climatological annual cycles of SST and SSS, respectively. The surface boundary condition on the SST implicitly includes a net radiative flux (diagnosed) and a physically realistic heat exchange with the atmosphere (restoring flux), while the boundary condition on the SSS is the real freshwater flux (diagnosed) as proposed by Huang (J. Phys. Oceanogr., 33 (1993) 2428). Apart from being based on physically realistic surface boundary conditions, the advantage of the method is that it results in a realistic model simulation of the observed annual cycle of SST and SSS with no artificial damping of surface watermass fronts. The resulting heat fluxes and freshwater sources are realistic if the observed climatological data and model internal physics are accurate. The performance of the method is demonstrated using the DieCAST ocean model adapted to the Mediterranean Sea where the obtained model fluxes are compared with observations. © 2004 Elsevier B.V. All rights reserved., We acknowledge MCyT and FEDER support from project IMAGEN REN2001-0802-C02-01/MAR. D. E. Dietrich acknowledges a grant from the Spanish ministry for Education and Culture (SAB1999-0037). V. Fernández acknowledges a FPI grant from the Spanish Ministry for Science and Technology (PN1998 36125588)