Climate Modelling Group
School of Earth and Ocean Sciences

The Thermohaline Circulation and Climate Variability of the North Atlantic

Canadian Participation in the World Ocean Circulation Experiment

[Picture of the Earth]
A Collaborative Special Project proposal submitted jointly to the Natural Sciences and Engineering Research Council , the Department of Fisheries and Oceans and the Atmospheric Environment Service (Canadian Institute for Climate Studies)
Date: May, 1995

Scientific Rationale for the WOCE proposal

1.1. Introduction

Over the past few years increasing public, political and scientific concern has been directed towards potential climate change associated with increasing greenhouse gases. The most recent and sophisticated climate forecasts (Manabe and Stouffer, 1993) have suggested that global warming will occur at a rate of 3.5 deg C per century associated with a 1%/year increase in atmospheric CO2 (close to the IPCC Business as Usual Scenario for atmospheric greenhouse gas emissions - IPCC, 1990, 1992). In the high latitudes of the northern hemisphere, the climate forecasts for a doubling of atmospheric CO2 further suggest an amplification of the warming (~8-9 deg C versus ~3 deg C for low latitude regions - IPCC, 1995) due to the reduction of sea ice cover and the accompanying decrease in surface albedo (amount of incoming solar radiation reflected back to space). In the region around Antarctica, very little change (or even slight cooling) is predicted over the next few centuries, due to the efficient absorption of heat by the ocean there.

Predictions of global climate change pose a public policy problem as to what, if anything, should be done to head off the threat created by emissions of greenhouse gases. In answering this question, the most widely accepted approach is to weigh the benefits of a given action against its costs. The comparison of the benefits and costs of actions in preventing/mitigating climate change requires a scientifically based climate change scenario and numerous economic assumptions. However, our present understanding of the climate system is insufficient to give the required information with a high degree of certainty. One of the biggest factors causing this uncertainty involves a lack of understanding of the role of the oceans in climate change and climate variability.

The ocean is well known to have a moderating effect on climate through several mechanisms. It is the buffer which moderates temperature fluctuations during the course of a day, from season to season and even from year to year. One only has to compare the maritime climate of Victoria, British Columbia (48 deg 25'N, 123 deg 22'W - Fig. 1), with average temperature of 4 deg C in January and 16 deg C in July, with the continental climate of Winnipeg, Manitoba (49 deg 54'N, 97 deg 14'W - Fig. 1), with average temperature of -18 deg C in January and 20 deg C in July, to see the moderating effect of the ocean. The ocean also acts as a large-scale conveyor that transports heat from low to high latitudes, reducing latitudinal gradients of temperature. Much of the oceanic heat transport is thought to be associated with the thermohaline circulation (that part of the ocean's circulation which is driven by fluxes of heat and freshwater through the ocean's surface). In the North Atlantic, intense heat loss to the overlying atmosphere causes deep water to be formed in the Greenland, Iceland and Norwegian (GIN) Seas. These sinking regions are fed by warm, saline waters brought by the thermohaline circulation from lower latitudes. No such deep sinking exists in the Pacific. Again, if one compares the climates of Bodo, Norway (67 deg 17'N, 14 deg 25'E - Fig. 1), with average January temperature of -2 deg C and average July temperature of 14 deg C, to that of Nome, Alaska (64 deg 30'N, 165 deg 26'W — Fig. 1), with average January temperature of -15 deg C and average July temperature of 10 deg C (both of which are at similar latitudes and on the western flanks of continental land masses), one directly sees the impact of the poleward heat transport of the thermohaline circulation. The ocean can also regulate climate through its ability to store both anthropogenic and natural greenhouse gases.

[Figure 1]

Figure 1: Map of the globe indicating the location of: Victoria, British Columbia; Winnipeg, Manitoba; Bodo, Norway; Nome, Alaska. The arrow schematically portrays the surface component of the North Atlantic thermohaline circulation (conveyor), which brings heat from the tropics to high latitudes where it is released to the atmosphere.

Through the 1960's and 1970's, oceanography evolved into an experimental science in which tightly focused studies of phenomena or processes were conducted. This has improved our understanding of many of the important building blocks of ocean dynamics, but unfortunately it has de-emphasized global-scale coordinated observational and modelling studies. Many oceanographers also realized that the existing methods of observation, involving ships and moored instruments, gave reliable spot measurements, but provided hopelessly inadequate coverage on the global scale. They foresaw that new methods involving satellites, automated drifters, and other innovative technologies would be required to set up a global-scale observational network and make continued progress in assessing, understanding, and monitoring the climatic role of the oceans. New methods would have to be found to use models in combination with data using assimilation techniques in order to fully exploit the observations and provide a complete picture of the global circulation. Models would have to be further developed, tested, and refined in the light of comparison with the new data sets.

The World Ocean Circulation Experiment (WOCE) was developed to address these concerns. WOCE will assess and model the heat and water fluxes by the world's oceans, and lay the groundwork for long-term monitoring. WOCE is focused on the physical role of the ocean in affecting climate on timescales of decades. The role of the ocean in the carbon cycle is the focus of another international collaborative program - the Joint Global Ocean Flux Study (JGOFS).

In recent years, the analysis of climatic data sets have documented substantial variability on the decadal to interdecadal timescale. For example, global surface air temperatures (Ghil and Vautard, 1991), sea surface temperature (SST) anomalies (Kushnir, 1993), West African rainfall and the landfall of intense hurricanes on the US coast (Gray, 1990), formation of the deep waters of the North Atlantic (Lazier, 1980; Schlosser et al., 1991), temperature and salinity characteristics and circulation of the North Atlantic (Roemmich and Wunsch, 1984; Dickson et al., 1988; Levitus, 1989a,b,c; Levitus, 1990; Greatbatch et al., 1991), Arctic sea ice extent (Mysak and Manak, 1989; Mysak et al., 1990), runoff from Eurasia (Cattle, 1985; Ikeda, 1990), global sea level pressure (Krishnamurti et al., 1986), all exhibit signals of decadal/interdecadal timescale. Studies using the instrumental data record are restricted to relatively short time series. Proxy climate data extends the record considerably. For example, Hibler and Johnsen (1979) used measurements of oxygen isotope ratios from an ice core to obtain a proxy air temperature record for Greenland spanning the years 1244 to 1971. This record exhibits a 20 year oscillation.

Researchers have postulated that the source of such decadal scale variability may well lie within the ocean. Many of the ocean observations further suggest that the ocean's thermohaline circulation plays a significant role; particularly the component associated with North Atlantic Deep Water formation. Indeed, this hypothesis was originally put forward by Bjerknes (1964) in his attempt to explain decadal/interdecadal changes in the SST of the North Atlantic (see Bryan and Stouffer, 1991 for a more complete discussion of Bjerknes, 1964). The Canadian oceanographic, meteorological and climate research community has considerable expertise, history and interest in the North Atlantic, especially the deep water formation regions of the subpolar gyre. For these reasons, we have decided that the overall scientific objective for the third phase of Canadian WOCE is:

To model and describe the thermohaline circulation and climate variability of the North Atlantic on the decadal to interdecadal timescale
Our approach will involve the integration of modelling and data analysis. A range of models and modelling approaches will be applied from the global scale through the regional scale to the local process-oriented models. In particular, two Canadian Community WOCE Modelling efforts (CCME1 and CCME2) are proposed (see section 2). The data analysis will involve not only those North Atlantic atmospheric, ocean and ice data sets collected during the WOCE period, but also those for the previous four decades.

The scientific objective outlined above can be further divided into four sub-objectives:

1.2 The volume and characteristics of water masses

Water mass distributions are powerful indicators of the state of the atmosphere-ocean climate system. An early application was by Benjamin Thompson, Count Rumford, (Fig. 2) who realized that the great masses of cold water which are observed throughout the deep ocean (even in regions where the surface water never gets cold) imply a global overturning circulation cell driven by convection in polar regions. Two centuries later, understanding this overturning (Fig. 3) is still a major scientific goal because of the central role it plays in the climate system as a pathway of heat redistribution. The cell is driven by water mass formation in isolated regions of strong air-sea buoyancy fluxes, acting in balance with general circulation patterns and mixing in the ocean interior. More recent descriptions of water mass formation also point to the important role that salinity (or freshwater fluxes) play in determining the strength of oceanic deep convection. Water mass inventories provide an integrating signature of various key components of the system.

[Figure 2]

Figure 2: Portrait of Sir Benjamin Thompson, Count Rumford taken in 1798 at the age of 45 (taken from Ellis, 1868).
The water masses of the sub polar North Atlantic have been observed through the IGY/ICES Polar Front surveys of 1957/58, the BIO subpolar gyre survey beginning in the winter of 1966/67 and the Transient Tracer in the Oceans survey of 1981. International WOCE is coordinating a modern survey of the subpolar gyre of the North Atlantic, culminating in a major field programme in the fall of 1996 and the spring and summer of 1997. In addition, the historical oceanographic data archives document the pentad to pentad changes of the temperature and salinity of these water masses from the late 1950's. During the last decade, annual repeat sections across the northern North Atlantic document these changes on a year to year basis.

[Figure 3]

Figure 3: Schematic diagram of the conveyor belt for North Atlantic Deep Water illustrating the global teleconnections associated with processes occurring in the North Atlantic (Taken from Broecker, 1991).
Numerical models are a prime tool in understanding the overturning circulation. Even if satisfactory climatologies or monthly distributions of the air-sea exchanges of heat and fresh water existed, present-day ocean models cannot resolve either the source terms in the water mass distribution balance (e.g. convective injection) or the loss terms (diapycnal mixing), since both terms involve sub-grid scale motions. The solution is to parameterize these processes. However, model results are fairly sensitive to the parameterization details (e.g. Bryan, 1987; Marotzke, 1991), which is problematic because the parameterizations are relatively crude, compared to what we have learned from process studies in WOCE-I and WOCE-II. Constraining the parameterizations is therefore a central theme of WOCE-III.

Parameterization constraints have been sought through process studies of convection and mixing, through model sensitivity studies and through integration of models and observations. The first two approaches were productively employed in previous phases of Canadian WOCE and should continue to provide insight. A powerful new way of constraining parameterizations relates back to Count Rumford's reasoning. It relies on the comparison of observed and predicted water mass inventories and geographical patterns. An advantage of inventory analysis is that it involves lumping data into histogram categories, with the result being a rejection of noise and the gain of statistical reliability. Because water mass inventories are controlled by a competition between air-sea fluxes and interior mixing, inventory analysis allows a back-calculation of air-sea fluxes in terms of interior mixing (Walin, 1982). An early success of the technique was the explanation of the relative volume and properties of water masses created by wintertime convection in sub-tropical regions (Speer and Tziperman, 1992). Extension to the water masses involved in global overturning will address a central goal in the international WOCE program, and is a thread that runs through many of the Canadian contributions described here.

Another prospect is that the averaging aspect of inventory analysis will yield resolvable signals of hydrographic variability over decadal timescales, allowing inference of changes in the mean climatic state. Finally, trustworthy constraints on surface fluxes should guide formulations of surface boundary conditions for heat and water fluxes, which are thought to be important in controlling the stability of thermohaline overturning.

Water masses undergo considerable changes in their volume and characteristics on decadal time scales (see also section 1.5). For example, in recent years, Labrador Sea water has been fresher and colder than ever previously observed (Lazier, personal communication). Integrating observations and models is a key issue in WOCE, and can provide a much greater wealth of information than can be obtained from observations alone. Data assimilation studies are included in this proposal. Such studies attempt to reconstruct climate change in the North Atlantic over recent decades, and hopefully, shed light on the important mechanisms.

1.3 Role of mixing and surface and boundary fluxes in determining water mass characteristics

The water mass formation in the North Atlantic plays a crucial role in determining the thermohaline circulation of the world ocean. Across the air-sea boundary, there are fluxes of heat and moisture that play an important role in water mass modification. These fluxes are also the intermediaries that couple the ocean circulation to that of the atmosphere. Three processes within the ocean act to determine the properties of water masses: advection; eddy and turbulent diffusion (mixing); convection.

Advection can be either directly measured, diagnostically determined from tracer fields or prognostically calculated using dynamic ocean models. More observations and higher resolution models are required to gain a better understanding of the circulation (see section 2.1). The mixing of water masses formed in the North Atlantic basins (Labrador and GIN Seas) with waters originating elsewhere is an important feature of water mass evolution. A number of schemes exist in numerical models to represent this mixing and these can be validated using tracer and hydrographic data.

Convection in the open ocean as a result of atmospheric forcing is recognized as the major source of deep water formation in the North Atlantic. These episodic events are difficult to observe and at present are crudely represented in numerical models. Within the Labrador and GIN Seas, little is known about the atmospheric processes that are responsible for fluxes of heat and moisture. The application of physically realistic atmospheric forcing fields may substantially improve our understanding of the role of deep convection in the thermohaline circulation of the world ocean and thereby improve the simulation of water mass properties. In addition, changes in the sea ice extent over the shelves may effect the air/sea fluxes over the deep convection regions offshore. Movement of sea ice and low salinity waters from the shelf to the offshore may also be a significant source of buoyancy to the convection regions and hence may cause interannual changes in water mass formation. Hence the shelf circulation and shelf/ocean exchange mechanisms are an important part of these investigations.

1.4 The dynamics and structure of the subpolar gyre and the abyssal circulation

The subpolar gyre and its extensions into the GIN and Labrador Seas are the source of the intermediate and deep waters of the North Atlantic. Conceptually, the subpolar gyre consists of a basin wide cyclonic circulation, equatorward density driven flows on the western continental shelves, deep cyclonic circulations in the individual basins trapped over the continental slopes and an upper ocean poleward flow from the subtropical gyre through to the GIN Seas. Furthermore, the North Atlantic is intimately coupled with the Arctic Ocean. Warm, saline North Atlantic waters enter the Arctic Ocean and are replaced by colder, fresher waters which return via Fram Strait. The components of this circulation are thought to play important roles in creating the conditions through which water masses can be formed and then in moving those water masses from their formation sites into the North Atlantic and hence the global ocean.

The Greenland and Labrador Currents flow southward along the shelf edge at the western boundaries of the subpolar gyre (see Fig. 4). These currents transport continental runoff and cold, low salinity waters from the Arctic Ocean. Lazier and Wright (1993) show that the Labrador Current core is centred over the 1000 metre isobath and that its baroclinic transport is 4E+6 m3/s, whereas its the barotropic transport is 7E+6 m3/s. Much of its seasonal variability is believed to arise from the seasonal variation of steric height on the Labrador shelf. Numerous difficulties exist in the numerical modelling of boundary currents and in particular whether and where separation from the coast occurs (e.g., Gan et al., 1995; Myers et al., 1995).

It is not certain what happens when the East Greenland Current reaches Cape Farewell, though little of the ice carried southward by this current turns and flows northward along west Greenland. The waters over the West Greenland shelves are warmer and saltier than those off East Greenland. Smith et al (1937) attributed this change to mixing of the offshore waters from the Irminger Sea with the East Greenland Current waters at Cape Farewell. This may be so; however, there is also a pool of low salinity surface water found directly south of Cape Farewell in the centre of the subpolar gyre (Clarke, 1984, Reynaud et al., 1995). The source of this water is not discussed in any of the conceptual models of the circulation in this region.

[Figure 4]

Figure 4: A schematic diagram of the North Atlantic surface circulation. The relevant abbreviations are as follows: Gulf Stream (Gu); North Atlantic Current (Na); Irminger Current (Ir); West Greenland Current (Wg); East Greenland Current (Og); Labrador Current (La); Norwegian Current (Ng); North Icelandic Current (Ni); East Icelandic Current (Oi). Taken from Krauss (1986).
The transport of the basic cyclonic circulation is thought to be 45E+6 m3/s (Clarke, 1984; Greatbatch et al., 1991; Reynaud et al., 1995), consistent with the Sverdrup flat-bottom response to climatological winds (Fig. 5). Clarke (1984) and Lazier and Wright (1993) present direct current observations from south of Cape Farewell and over the Labrador slope to suggest that this transport appears as a largely barotropic current centred around the 2500 metre isobath. Most of this circulation is found to the north of 50 N; however, a narrow tongue may extend south of Flemish Cap down to the tail of the Grand

[Figure 5]

Figure 5: Transport (in Sverdrups, Sv; 1Sv=1E+6 m3/s)of the summer mean circulation in the western North Atlantic. Taken from Reynaud et al. (1995).
Banks of Newfoundland. In addition, Greatbatch and Xu (1993) note that for the subpolar gyre circulation to satisfy mass balance, the southward return flow offshore of Labrador must be largely barotropic. This is important as it prevents the usual western intensification of the wind driven subpolar gyre circulation, and leads, instead, to control of the circulation by f/H contours.

A combination of wind and buoyancy driving conspire to complicate even a laminar, steady state description of the dynamics governing these flows. The problem is further complicated by strong seasonal and interannual variability in the forcing. Also unresolved is the role of transient eddies, which probably play an important role in determining the mean circulation. For example, eddy-induced form drag between the surface mixed layer and the thermocline must work together with the lateral eddy fluxes of heat and salt such that the time mean flow in the mixed layer satisfies constraints imposed by the angular momentum and heat budgets.

The overflows of the various components of North Atlantic Deep Water across the Shetland-Faroe-Iceland-Greenland ridge system feed a set of bottom currents that flow in a cyclonic sense along the continental slopes and flanks of the mid-ocean ridges (McCartney, 1992). These waters eventually enter the rest of the North Atlantic along the continental rise to the east of the Grand Banks of Newfoundland. The overflows exit the GIN Seas with transports of 1-3E+6 m3/s. Entrainment as these flows descend toward their equilibrium depths increases this transport to 12-15E+6 m3/s (Figs. 6, 7) by the time Cape Farewell is reached (Clarke, 1984, McCartney, 1992). As one moves further downstream, the waters in these bottom boundary currents gradually become warmer. There are also suggestions that there may be closed recirculations of the abyssal waters within particular basins related to particular bathymetric features.

[Figure 6]

Figure 6: A schematic diagram of the deep North Atlantic thermohaline circulation. The transport values indicated are in Sverdrups (1Sv=1E+6 m3/s). Taken from Dickson et al. (1990).
The upper ocean flow of water to the GIN Seas required to close the meridional cell has not been clearly identified observationally. With an East Greenland Current transport of 5E+6 m3/s and deep overflows of the same magnitude entering the North Atlantic from the GIN Seas and 12-15E+6 m3/s or so of North Atlantic Deep Water entering the subtropical gyre east of Newfoundland, there must be equivalent exchanges of water between gyres.

[Figure 7]

Figure 7: A schematic diagram of the deep North Atlantic thermohaline circulation. The transport values indicated are in Sverdrups (1Sv ļ 106 m3s–1). Taken from Schmitz and McCartney (1993).
With the exception of models aimed at understanding the possible role of hydraulics in governing the overflows, dynamical models of this circulation are largely based on either the Stommel-Arons model (Stommel and Arons, 1960) or on Stommel's box model, (Stommel, 1961). Surprisingly, the two bodies of literature rooted in this pioneering work have remained quite distinct (but see Wright et al., 1995). One of the primary reasons for this is probably that the rate of deep water formation is specified in the Stommel-Arons approach, whereas in circulation models (including simple box models like that of Stommel, 1961), the rate of deep water formation is a free variable. The two constituent nature of sea water can lead to considerable variability in the formation rate of deep water, favouring the use of circulation models. Both bodies of literature consider only dissipative western boundary layer dynamics, so that an adequate description of these currents and their associated recirculations remains lacking.

1.5 Processes controlling variability at seasonal to decadal time scales

The meridional circulation characterised by the northward transport of warm salty water by the Gulf Stream and the southward transport of cold fresh water by the Labrador Current plays a very important role in determining the oceanographic conditions in the North Atlantic, and through the air-sea interaction influences the atmospheric climate. These western boundary currents and their extensions in the North Atlantic have been shown to exhibit significant variability on seasonal to interdecadal time scales. Thompson and Hazen (1983) have shown that the wind forcing over the North Atlantic has a substantial seasonal component, which in turn establishes similar time scale variability in the Labrador Current transport (Thompson et al., 1986; Greatbatch et al., 1990; Lazier and Wright, 1993). The seasonal variability in the air-sea fluxes also affect a strong seasonal variation in the upper-ocean hydrography. Another consequence of the seasonal variability in the atmospheric forcing is the ice production in the Arctic and on the shelves of Labrador and Newfoundland, and the subsequent transport of pack ice to lower latitudes and offshore. The resulting freshwater flux combined with terrestrial drainage not only have a direct impact on the hydrography of the shelf and adjacent ocean, but also affect the buoyancy forcing and associated oscillations in the baroclinic segment of the Labrador Current (Lazier and Wright, 1993). The interannual variability in the seasonal cycle, on the other hand may be involved in the generation of such events as the Great Salinity Anomaly (Dickson et al., 1988) that may affect the entire water column.

Not all decadal scale variability appears in the North Atlantic; nor is variability in North Atlantic Deep water formation the only possible forcing mechanism. Recent hypotheses suggest that decadal variability in the Pacific may be either linked to changes in the El Niño signal in the equatorial Pacific (Trenberth and Hurrell, 1994) or to midlatitude air-sea instabilities (Latif and Barnett, 1994). It is not clear whether similar mechanisms exist in the Atlantic or whether there is a relationship between the Pacific and Atlantic modes of variability. Nevertheless, there is little doubt that decadal to interdecadal variability of the thermohaline circulation in the North Atlantic is a robust feature of the climate of the North Atlantic (e.g., Deser and Blackmon, 1993; Kushnir, 1994; Delworth et al., 1993 - see also Fig. 8).

[Figure 8]

Figure 8: Monthly average of salinity at 11 depths at Ocean Weather Station Bravo (56 deg 30' N, 51 deg 00' W). The data were collected from 1964-1973 (taken from Lazier, 1980). This figure illustrates dramatic changes in the property of Labrador Sea deep convection during the passage of the Great Salinity Anomaly.
Under mixed boundary conditions (where an air/sea salinity flux is specified and surface temperature is again restored to climatology) self-sustained internal variability on the decadal/ interdecadal timescale can exist in ocean models (e.g., Weaver and Sarachik, 1991; Weaver et al., 1991, see Weaver and Hughes 1992, for a review). Often this variability is linked to the turning on and shutting off of high latitude convection and the subsequent generation and removal of east-west steric height gradients which cause the thermohaline circulation to intensify and weaken over a decadal timescale. The fact that decadal variability can occur in uncoupled ocean models in basins where deep water formation occurs makes it difficult to interpret causes and effects of decadal variability in the coupled system.

Interdecadal variability has also been found in ocean models run under constant flux boundary conditions. For example, Greatbatch and Zhang (1995) describe an oscillation with many features like that found in the Geophysical Fluid Dynamics (GFDL) fully-coupled ocean atmosphere model (Delworth et al., 1993). Winton (1995) has pointed out the possible importance of boundary waves in models that exhibit decadal-interdecadal variability. The role of boundary waves, for both constant flux and mixed boundary condition oscillations, has since been confirmed by Greatbatch and Peterson (personal communication). The inadequate resolution of the coastal wave guide in current climate models indicates the need for higher resolution studies to test the robustness of interdecadal variability in models. High resolution models are planned as part of this proposal (see section 2.1), and will be used to address this issue.

The ocean modelling community has often used restoring boundary conditions where the surface temperatures and salinities in an ocean model are relaxed, with a specified timescale, to some climatological values. Another choice are the mixed boundary conditions mentioned above. Sea surface temperature anomalies, regardless of their scale, are strongly damped under restoring boundary conditions. In reality, the damping time should depend on the scale of the anomaly since latent and sensible heat loss are inefficient mechanisms for the removal of large-scale sea surface temperature anomalies. This follows since heat lost over one part of the ocean must be advected by the atmospheric winds away from the anomaly for it to be effectively removed. Therefore, as pointed out by Bretherton (1982), in the limit of a global scale anomaly radiational damping (long timescale) is the only mechanism for its removal.

These ideas have been utilized in the development of a number of improved parameterizations of the thermal surface boundary condition (e.g., Zhang et al., 1993; Mikolajewicz and Maier-Reimer, 1994; Rahmstorf and Willebrand, 1994; Seager et al., 1994). A cautionary note should be added here regarding the variability found in ocean GCMs under mixed boundary conditions. It is evident from these new surface boundary condition parameterizations that much of the variability is either damped or modified when more realistic surface boundary conditions are used. One should therefore continue to view early results with some caution until they are verified with fully-coupled ocean-ice-atmosphere models. This is currently a very active area of research which is being investigated by many groups internationally.

It is evident from the preceding discussion that in order to obtain a better understanding of natural climate variability on the decadal to interdecadal timescale, more realistic coupled atmosphere-ocean-ice models must be used. The knowledge gained from the uncoupled ocean models under a variety of boundary conditions of increasing sophistication, and using increasing resolution, will be crucial to understanding the variability found in the coupled system.

1.6. Summary

The development of a quantitative understanding of the thermohaline circulation, and its decadal variability, is in its early stages. Observations and simple models together are needed to map the water masses and their exchange rates, and also identify the important dynamical controls on the overall circulation. Numerical models, after development and validation, will provide a means of reconstructing past changes, and ultimately predicting future changes, in ocean climate on regional to global scales.

The Canadian contribution to WOCE will focus on the North Atlantic, arguably the best-observed ocean and certainly one of the most active parts of the thermohaline circulation. The team will comprise many of Canada's best ocean scientists drawn from both Canadian Universities and the Department of Fisheries and Oceans. It will bring together observationalists, theoreticians and numerical modellers in a highly-intensive and focused research programme. The following approaches will be adopted:

1)- Collection of key observations, taking advantage of the new generation of ocean instrumentation including satellite altimeters and autonomous, Lagrangian, subsurface observing platforms.
2)- Synthesis of observations and simple dynamical constraints to identify the factors controlling the thermohaline circulation and its variability.
3)- Development and validation of a hierarchy of models aimed at providing quantitative understanding of the thermohaline circulation and decadal-interdecadal climate variability in the North Atlantic.
4)- Development and operation of two community models: A regional North Atlantic high-resolution model and a global ocean model.
The focus on the North Atlantic and the development of the community models will facilitate strong interactions among team members. It will also ensure that Canada makes a unified contribution to the international WOCE program, involving both observations and models, thereby enhancing our understanding of the ocean's physical role in climate change.

1.7. References

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Lazier, J.R.N. and D.G. Wright, 1993. Annual Velocity Variations in the Labrador Current. J. Phys. Oceanogr. 23, 659-678.
Levitus, S., 1989a: Interpentadal variability of temperature and salinity at intermediate depths of the North Atlantic Ocean, 1970-74 versus 1955-59. J. Geophys. Res., 94, 6,091-6,131.
Levitus, S., 1989b: Interpentadal variability of salinity in the upper 150m of the North Atlantic Ocean, 1970-74 versus 1955-59. J. Geophys. Res., 94, 9,679-9,685.
Levitus, S., 1989c: Interpentadal variability of temperature and salinity in the deep North Atlantic, 1970-74 versus 1955-59. J. Geophys. Res., 94, 16,125-16,131.
Levitus, S., 1990: Interpentadal variability of steric sea level and geopotential thickness of the North Atlantic Ocean, 1970-74 versus 1955-59. J. Geophys. Res., 95, 5,233-5,238.
McCartney, M.S., 1992. Recirculating components to the deep boundary current of the northern North Atlantic. Prog. Oceanogr., 29, 283-383.
Manabe, S., and R.J. Stouffer, 1993: Century-scale effects of increased atmospheric CO2 on the ocean-atmosphere system. Nature, 364, 215-218.
Marotzke, J., 1991: Influence of convective adjustment on the stability of the thermohaline circulation. J. Phys. Oceanogr., 21, 903-907.
Mikolajewicz, U., and E. Maier-Reimer, 1994: Mixed boundary conditions in ocean general circulation models and their influence on the stability of the model's conveyor belt, J. Geophys. Res., 89, 22,633-22,644.
Myers, P.G., A.F. Fanning and A.J. Weaver, 1995: JEBAR, bottom pressure torque and Gulf Stream separation. J. Phys. Oceanogr., submitted.
Mysak, L.A., and D.K. Manak, 1989: Arctic sea-ice extent and anomalies, 1953–1984. Atmos.-Ocean, 27, 376-405.
Mysak, L.A., D.K. Manak, and R.F. Marsden, 1990: Sea-ice anomalies in the Greenland and Labrador Seas during 1901-1984 and their relation to an interdecadal Arctic climate cycle. Climate Dyn., 5, 111-133.
Rahmstorf, S., and J. Willebrand, 1994: The role of temperature feedback in stabilising the thermohaline circulation. J. Phys. Oceanogr., in press.
Reynaud, T.H., Weaver, A.J. and Greatbatch, R.J. 1995: Summer mean circulation in the western North Atlantic. J. Geophys. Res., 100, 779-816.
Roemmich, D., and C. Wunsch, 1984: Apparent changes in the climatic state of the deep North Atlantic Ocean. Nature, 307, 447-450.
Schlosser, P., G. B. Anisch, M. Rhein, and R. Bayer, 1991: Reduction of deepwater formation in the Greenland Sea during the 1980s: Evidence from tracer data. Science, 251, 1,054-1,056.
Schmitz, W.J., Jr. and M.S. McCartney, 1993: On the North Atlantic circulation. Rev. Geophys., 31, 29-49.
Seager, R., Y. Kushnir and M.A. Cane, 1994: A note on heat flux boundary conditions for ocean models. J. Phys. Oceanogr., submitted.
Smith, E.M., F.M. Soule and O. Mossby, 1937. The Marion and General Green Expeditions to Davis Strait and Labrador Sea. Bull. U.S. Coast Guard, 19, 259 pp.
Speer, K. and E. Tziperman, 1992: Rates of water mass formation in the North Atlantic Ocean. J. Phys. Oceanogr., 22, 93-104.
Stommel, H., 1961: Thermohaline convection with two stable regimes of flow. Tellus, 13, 224-230.
Stommel, H., and A.B. Arons, 1960: On the abyssal circulation of the world ocean—II. An idealized model of the circulation pattern and amplitude in oceanic basins. Deep-Sea Res., 6, 217-233.
Thompson, K.A., and M.G. Hazen, 1983: Interseasonal changes of wind stress and Ekman upwelling: North Atlantic, 1950-1980. Can. Fish. Aquat. Sci. Tech. Rep. No. 1214, 175pp.
Thompson, K.R., J.R.N. Lazier and B. Taylor, 1986: Wind forced changes in the Labrador Current transport. J. Geophys. Res., 91, 14,261-14,268.
Trenberth, K.E., and J.W. Hurrell, 1994: Decadal coupled atmosphere-ocean variations in the North Pacific Ocean. Can. J. Fish. Aquat. Sci., 51, in press.
Walin, G., 1982: On the relation between sea-surface heat flow and thermal circulation in the ocean. Tellus, 34, 187-195.
Weaver, A.J., and E.S. Sarachik, 1991: Evidence for decadal variability in an ocean general circulation model: An advective mechanism. Atmos.-Ocean, 29, 197-231.
Weaver, A.J., and T.M.C. Hughes, 1992: Stability and variability of the thermohaline circulation and its link to climate. Trends in Physical Oceanography, Research Trends Series, Council of Scientific Research Integration, Trivandrum, India, 1, 1-570.
Weaver, A.J., E.S. Sarachik and J. Marotzke, 1991: Freshwater flux forcing of decadal and interdecadal oceanic variability. Nature, 353, 836-838.
Winton, M., 1995: On the role of horizontal boundaries in parameter sensitivity and decadal-scale variability of coarse-resolution ocean general circulation models. J. Phys. Oceanogr., submitted.
Wright, D.G., C.B. Vreugdenhil and T.M.C. Hughes, 1995: Vorticity dynamics and zonally averaged ocean circulation models. J. Phys. Oceanogr., in press.
Zhang, S., R.J. Greatbatch and C.A. Lin, 1993: A reexamination of the polar halocline catastrophe and implications for coupled ocean-atmosphere modelling. J. Phys. Oceanogr., 23, 287-299.

2. Canadian Community Modelling Efforts

In order to facilitate and foster the collaborations between University, DFO and AES researchers initiated during WOCE-I and WOCE-II, a number of community models will be developed or made available during WOCE-III. In addition, all data collected under the WOCE umbrella by Canadian oceanographers has and will continue to be submitted to the appropriate WOCE Data Acquisition Centre where it is subjected to various data quality control procedures before being placed in the WOCE data set. Under the international WOCE data sharing policy, all WOCE data is to be freely exchanged within two years of the data being collected. The status and location of various WOCE data sets is electronically available from the WOCE Data Information Unit. Canadian oceanographic groups have been working during the first 5 years of WOCE to improve our data processing procedures in order to meet these WOCE data delivery schedules. Most data can now be delivered to the WOCE data centres within the prescribed times. Historic data sets are also being reprocessed to the WOCE standards. During the third phase of WOCE, there will be a greater effort made to create data products from the WOCE and earlier data sets and these products as well as the data that goes into them will be advertised and freely exchanged within the Canadian community.

The Community Modelling efforts will focus around the high-resolution regional North Atlantic model which will be developed by Drs. D. Wright and A. Clarke at BIO, D. Kelley and B. Ruddick at Dalhousie University and A. Weaver at the University of Victoria (section 2.1). In addition, Dr. A. Weaver will provide and maintain a global ocean model developed in collaboration with the Atmospheric Environment Service (see section 2.2). Funding for the support of these two community modelling efforts is requested from AES (see section 5).

The low-order climate model developed by Drs. D. Wright (at BIO) and T. Stocker (now at the University of Bern) will also be made available to all participants in WOCE-III. The model is quite general and can be configured with various degrees of complexity, ranging from a very simple Stommel-style ocean-only model to a fully coupled global ocean-atmosphere-sea-ice model. The ocean component allows for either the simple approach taken by Wright and Stocker (1991) or the more dynamically consistent approach of Wright, Vreugdenhil and Hughes (1995). The atmospheric component is presently a 1-dimensional (north-south) Energy Balance Model (see Stocker et al., 1992) but it is being extended to account for longitudinal variations that are consistent with the basin scale resolution of the ocean component. The model also includes a thermodynamic sea-ice component and a full suite of tracers, including colour tracers, ideal age tracers, radioactively decaying tracers and an inorganic carbon component.

The availability of the computationally efficient low-order climate model will be extremely useful for the examination of climate processes and feedbacks on timescales of a decade or greater. Furthermore, parallel experiments conducted with the low-order climate model will aid in the understanding of the results obtained from the more complicated coupled models detailed in the attached proposals.

Continued development of this low-order model is already funded under the NSERC/AES Collaborative Special Project "Climate System History and Dynamics" and no additional funding is being requested under the present project. A preliminary user manual is available as an introduction to the model and will be provided, along with the code, to WOCE-III researchers.

2.1. A Canadian Community High-Resolution Regional North Atlantic Model (CCME1)

As part of this proposal, it is planned to develop a high resolution model of the North Atlantic Ocean for climate studies. Funding for this part of the proposal is being sought from the Canadian Climate Research Network, through the Canadian Institute for Climate Studies (see section 5). The model will be developed at BIO under the direction of Drs. D. Wright, A. Clarke, D. Kelley, B. Ruddick and A. Weaver. This modelling effort will eventually form a resource for the Canadian oceanographic/climate community, although in the first few years, considerable development work will be required. The need to trace the deep water pathways from their source regions in the Labrador and GIN Seas was emphasized in section 1. Recent observations have found deep water in the Irminger Sea, on the other side of the North Atlantic, only a few years after its formation in the Labrador Sea (Lazier, personal communication), yet the pathway by which the new water moves to the Irminger Sea is not known. A high resolution model is required to answer questions such as this, and also to study mechanisms by which changes in deep water properties, and interdecadal variability, take place in the North Atlantic climate system (see section 1.5).

2.2. A Canadian Community Global Model (CCME2)

During the last funding period of the NSERC/WOCE Collaborative Special Project (CSP), Dr. A. Weaver at the University of Victoria, in collaboration with the Canadian Climate Centre (CCC) of the Atmospheric Environment Service (AES), developed a global ocean model. Two versions of this model now exist: The first version is a high resolution model (1.8 deg x 1.8 deg x 29 levels) and is being coupled to the CCC Atmospheric General Circulation Model (AGCM) for use in climate prediction studies. The second version of the model is at slightly coarser resolution (3.6 deg x 1.8 deg x 19 levels) and is being used to understand the structure, stability and variability of the global ocean thermohaline circulation (see Weaver and Hughes, 1995).

The North Atlantic thermohaline circulation is thought to be integrally connected to all the world oceans (Fig. 3). The coarse version of the global model will therefore be used as an experimental laboratory to examine the global consequences of processes operating in the North Atlantic. This global modelling facility will be offered by Dr. Weaver as a CNC WOCE community model in order to avoid the unnecessary duplication of effort in creating additional models by other WOCE Principal Investigators. Dr. Weaver will operate this facility at the University of Victoria and will ask a Scientific Computing Research Associate to undertake the global model simulations for CNC WOCE users. This global ocean model has recently been given to Prof. Bill Gough at the University of Toronto (a prospective WOCE-III PI), to initiate a collaboration on the influence of spurious cross-isopycnal mixing due to lateral diffusivity in regions of sloping isopycnals (the "Veronis effect"). Funding for this part of the proposal is being sought from the Canadian Climate Research Network, through the Canadian Institute for Climate Studies (see section 5).

2.3. References

Stocker, T.F., D.G. Wright and L.A. Mysak, 1992: A zonally averaged, coupled ocean-atmosphere model for paleoclimate studies. J. Climate, 5, 773-797.
Weaver, A.J., and T.M.C Hughes, 1995: Flux corrections in coupled ocean-atmosphere models. Climate Dynamics, submitted.
Wright, D.G., and T.F. Stocker, 1991: A zonally averaged ocean model for the thermohaline circulation. Part I: Model development and flow dynamics. J. Phys. Oceanogr., 21, 1713-1724.
Wright, D.G., C.B. Vreugdenhil and T.M.C. Hughes, 1995: Vorticity dynamics and zonally averaged ocean circulation models. J. Phys. Oceanogr., in press.

3. Relationship to International Programs

3.1. Introduction

In a recent Report of the National Advisory Board on Science and Technology, Committee on Oceans and Coasts, presented to the Prime Minister of Canada (May, 1994) four reasons were provided as to why the Government of Canada should act to implement an oceans management strategy that includes the enactment of a Canada Oceans Act. One of these reasons is:
"to focus science research on understanding the complex interrelationships of climate change and ocean ecosystem behaviour so that we can make informed decisions about resource management" (page 46)
The Report further notes that Canadian scientists are major contributors to programs such as the WCRP (WOCE and CLIVAR) (page 36) and recommends the continuation of Canadian participation in international science activities (page 51).

3.2. International Links and Participation

The Canadian contribution to WOCE is intimately linked in with international (see Boxes 1–3 which were taken from Ocean Studies Board, 1994) WOCE Core Projects 1 and 3 for a global survey and gyre dynamics study, respectively. Our project is also central to the goals of the United States WOCE and NOAA Atlantic Climate Change Programs. In these programs three key scientific goals were identified:
1)- To synthesize existing and new, oceanic and atmospheric data from the North Atlantic to:
a)- develop a quantitative understanding of ocean circulation consistent with the data.
b)- Improve understanding of the relationships between the rates and variability of meridional overturning and the variability of the overlying atmosphere.
2)- To provide a quantitative, three-dimensional description of the pathways and transports of the meridional circulation within the North Atlantic Ocean. This will include a one-time basin-wide snapshot and time-dependent measurements during an intensive field program.
3)- To identify and initiate procedures that can be continued beyond the intensive observational period to monitor those processes expected to control the meridional circulation’s role in climate change.
The scientific goals of our present WOCE CSP (detailed in section 1.1) blend with the US WOCE and NOAA ACCP goals and allow us to build upon the expertise of the Canadian oceanographic community.

A number of WOCE-III researchers are already involved in the above international programs. Dr. Allyn Clarke is a member and vice-chair of the Joint Scientific Committee of the World Climate Research Programme (WCRP) and is past chair of the Scientific Steering Group for WOCE. Dr. J. Lazier was a member of WOCE Core Project 3 working group on the North Atlantic, while Dr. F. Dobson is a member and co-chair of the WOCE/CLIVAR XBT planning committee. Dr. Lazier, is also a co-PI (with. Dr. P. Rhines at the University of Washington) of a project funded by the NOAA ACCP, while Drs. Greatbatch and Weaver are also involved with the NOAA ACCP program as invited speakers at the annual NOAA ACCP PI meetings. In addition, Dr. B. Ruddick and N. Oakey were co-PIs on NATRE, one of the main process experiments carried out in the North Atlantic. Dr. N. Oakey was also a PI (with Dr. D. Hebert at the University of Rhode Island) in a US GLOBEC study on ocean mixing on Georges Bank.

The University Corporation for Atmospheric Research (UCAR) has recently developed a Climate System Modeling Program (CSMP) Project on Decadal-Centennial Variability of the Oceanic Thermohaline Circulation, through funding from the US National Science Foundation and the Department of Energy. Dr. Weaver is a member of this project and is actively involved in its progress. As part of this CSMP, Dr. Weaver is acting as a co-host (with Drs. I. Fung and C. Garrett) of a UCAR CSMP funded postdoctoral fellow (Dr. A. Tandon).

The US Office of Naval Research has recently developed an Accelerated Research Initiative (ARI) on Convective Overturning Processes. This program was designed to investigate how dense water, formed at the surface through surface buoyancy loss to the atmosphere, penetrates the interior of the ocean and reestablishes a stable stratification. Dr. K. Moore is a PI on the Deep Convection in the Labrador Sea Experiment of this ARI. He will be able to provide important linkages between WOCE-III and the ARI.

The World Climate Research Program recently approved the establishment of a major new fifteen year international program on Climate Variability (CLIVAR). This program is designed to study climate variability and predictability and the response of the climate system to anthropogenic forcing. Our WOCE-III project is well linked in with the following specific objective taken from the CLIVAR Science Plan:

The CLIVAR programme has initially been organized into three component programmes:
1)- CLIVAR-GOALS: A study of seasonal-to-interannual global climate variability and predictability;
2)- CLIVAR-Dec-Cen: A study of decadal-century global climate variability and predictability;
3)- CLIVAR-ACC: A study of the response of the climate system to the addition of radiatively active gases and aerosols to the atmosphere.
The goals and objectives of WOCE-III, outlined in section 1.1, are closely related to the specific scientific goals of CLIVAR-DecCen: Dr. A. Weaver was a member of the WCRP Steering Group on Global Climate Modelling which held its last meeting in San Diego in late 1994. This WCRP committee has since been disbanded in light of the development of CLIVAR within the WCRP. Dr. Weaver has since been invited to sit on the CLIVAR-DecCen Numerical Experimentation Group. He is also a lead author for both Chapters 5 and 6 of the United Nations Intergovernmental Panel for Climate Change (IPCC) 1995 Second Scientific Assessment and is a principal investigator in the NOAA Consortium on the Ocean's Role in Climate.

Internationally, WOCE will phase out by the turn of the century and be replaced by the CLIVAR initiative. WOCE-III has recognized this international thrust and hence this will be the last Collaborative Special Project proposal submitted to NSERC for the support of Canadian Participation in WOCE.

Within Canada, Dr. C. Lin sits on the Canadian Committee for Land Ocean Interaction in the Coastal Zone, an IGBP program, Dr. Ruddick sits on the DFO National Climate Committee while Dr. A. Weaver sits on the Canadian National Committee for Climate Research. In addition, Dr. Weaver is a member of the North Pacific Marine Sciences Organization (PICES) - Working Group 7: Modelling the Subarctic North Pacific Circulation.


Box 1 - Focus and Goals of the Major Research Programs



Focus: Studies of the surface and subsurface circulation of the global ocean.

Goal: To understand ocean circulation well enough to model its present state, predict its future state, and predict feedback between climate change and ocean circulation.


Focus: Observations needed for prediction of El Niño-Southern Oscillation and detection of global change due to greenhouse warming.

Goal: To provide the oceanic component of the Global Climate Observing System.


Focus: Studies describing the interactions between the tropical oceans and the global atmosphere, especially the El Nino-Southern Oscillation.

Goal: To model the ocean-atmosphere system for the purpose of predicting its variations.


Focus: Studies investigating the role of marine organisms and chemistry in modulating global climate change.

Goal: To gain a better understanding of how carbon dioxide is exchanged between the atmosphere and the surface ocean and how carbon is transferred to the deep sea.


Focus: Studies elucidating how changing climate alters the physical environment of the ocean and how this in turn affects marine animals, especially zooplankton and fish.

Goal: To predict the effects of changes in the global environment on the abundance, variation in abundance, and production of marine animals.


Focus: A combination of studies utilizing historical data, modeling, and direct observation and monitoring of middle and high latitudes of the North Atlantic.

Goal: To understand air-sea interactions between the Atlantic Ocean and the global atmosphere.


Focus: Acoustic propagation studies measuring the speed of sound along long distance undersea paths.

Goal: To characterize warming trends in the ocean on global scales.


Focus: Studies investigating the variations in sea-surface temperature, soil moisture, sea ice, and snow and the processes that control these conditions.

Goal: To gain a better understanding of global climate change variability on seasonal to interannual time scales for the purpose of predicting this variability.


Focus: Studies of fluxes in the coastal zone, how changes in the coastal zone alter the fluxes, and how they will affect the global carbon cycle and trace gas composition of the atmosphere.

Goal: To understand the impacts from changes in climate, sea level, land use, and ecosystem functioning for use in the creation of long-term, sustainable policies for coastal management.


Focus: Paleoenvironmental multidisciplinary studies to address the physical, chemical, biological, and social processes of the Arctic system.

Goal: To understand the processes of the Arctic system in order to predict environmental change on decade-to-century time scales.



Focus: Collection and analysis of deep-sea cores from around the world to help reconstruct the paleoceanographic record of past climatic and oceanic conditions.

Goal: To reconstruct the Earth's paleoceanography and more importantly to begin to understand the mechanisms that drive changes in climate and oceanic conditions.


Focus: Integrated observational, experimental and theoretical studies to determine the primary processes that have shaped the evolution of our planet, and the long-term temporal variations that may have modified the past climate of Earth.

Goal: To understand the causes and predict the consequences of physical, chemical, and biological fluxes within the global spreading center system.


Focus: Paleoclimate and current climate processes research addressing environmental change related to increasing human activities.

Goal: To provide relevant information on global climate change to the government and the research communities.


Focus: Studies of the paleoceanographic record to address numerous research themes including ocean geochemical and climate change and climate sensitivity and variability.

Goal: To determine the sensitivity of the climate system to natural changes in solar radiation.


Box 2 - Major WOCE Accomplishments

1)- Initiation of global-scale in situ measurements of mid-depth circulation following the successful development and testing of free-drifting ALACE floats and advances in float technology

2)- Determination of full-depth currents in the equatorial Pacific region by use of lowered Acoustic Doppler Current Profilers (ADCPs).

3)- Direct long-term measurements of the variability in formation rate and transport of North Atlantic Deep Water in the North Atlantic Ocean.

4)- The most complete and accurate description of water masses in the Pacific and South Atlantic oceans as a result of the WOCE Hydrographic Program.

5)- Initiation of measurements to provide the first global inventories of chlorofluorocarbons, helium, tritium, and carbon dioxide.

6)- New estimates of the vertical diapycnal diffusivity during both summer and winter in the central North Atlantic.

7)- An intensive study of the process of subduction in the upper ocean thermocline.

8)- Improved air-sea flux estimates in models resulting from, for example, the inclusion of satellite surface wind-speed data and real-time ice cover data, better stratus cloud parameterization, and the use of an improved spectral statistical interpolation objective analysis system.

9)- New estimates of the meridional heat flux across mid-latitudes in the South Pacific and North and South Atlantic, suggesting an imbalance in heat transport between the northern and southern hemispheres.

10)- Improved fine-scale global ocean models with more realistic physics and bathymetry, driven by real data rather than climatology.

11)- Establishment of data assembly centers and their associated quality control methods as a basis for better data management and data sharing.

12)- Contributions to the analysis of satellite-altimeter data from the Ocean Topography Experiment (TOPEX/Poseidon) and the European Remote Sensing (ERS-1) satellite missions, leading to an estimated orbit uncertainty of 8-9 cm with a geographically correlated component of better than 3 cm and to an improved surface wind field from scatterometer measurements.

13)- Establishment of a facility for measuring radiocarbon in small volumes of sea water and other matrices using Accelerator Mass Spectrometry.

14)- Development of a multiple XBT launcher for high-resolution XBT deployments on Voluntary Observing Ships.


Box 3 - Future Plans for WOCE

1)- Completion of an integrated study of the Indian Ocean beginning in late 1994.

2)- Enlargement of global drifter and float data sets and improved measurements of deep flow from current meter deployments.

3)- Complete process studies in the Atlantic Ocean.

4)- Launching of the advanced Earth Observing Satellite (NSCATT/ADEOS) plus other satellites to improve global wind field determination.

5)- Continued improvements in modeling, including methods for data assimilation.

6)- Implementation of a major synthesis phase from 1998 through about 2005 to extract the maximum information from the WOCE data sets.

7)- Transfer of pertinent information to those planning of the ocean component of the GCOS.

8)- Transfer of selected long-term measurements (e.g., upper ocean temperature and salinity from VOSs) to a follow-on global change research program or to the GOOS.


3.3. Reference

Ocean Studies Board, 1994: The Ocean's Role in Global Change: Progress of Major Research Programs. Prepared by the Ocean Studies Board, Commission on Geosciences, Environment and Resources, National Research Council. National Academy Press, Washington, D.C.

4. Department of Fisheries and Oceans Funding Request

This Collaborative Special Project proposal contains both individual and team proposals from university- and DFO-based researchers (see Fig. 9). All the proposals focus around the central theme of WOCE-III, namely:
To model and describe the thermohaline circulation and climate variability of the North Atlantic on the decadal to interdecadal timescale.
[Figure 9]
Figure 9: Schematic diagram illustrating the different proposals (team, individual, DFO, DFO/University) which are submitted as part of this Collaborative Special Project. All proposals are fundamentally linked about the central theme of WOCE-III. AES collaboration, through the global ocean modelling, regional ocean modelling and climate variability (CLIVAR) aspects of this proposal are also illustrated.
The requested DFO contribution towards this Collaborative Special Project is through salary, infrastructure and operating support of DFO-based researchers and through ship time granted to DFO researchers.

5. Atmospheric Environment Service (Canadian Institute for Climate Studies) Funding Request

Direct funding is requested from the Atmospheric Environment Service via the Canadian Institute for Climate Studies for the community modelling efforts outlined in sections 2.1 and 2.2. The regional climate modelling project (CCME1) will provide important information on the role of eddies in transporting heat and salt. It will allow for better resolution of important boundary layer processes and the coastal wave guide (see section 1.5). Furthermore, it will allow for the development of improved parameterizations of sub-grid scale mixing processes for use in the coarser resolution global ocean models. CCME1 will also yield a quantitative understanding of the circulation of the western North Atlantic, a region of particular importance to both global and Canadian climate.

The direct funding request for CCME1 is detailed in Table 1 below. For the 1995-96, 1996-97 and 1997-98 fiscal years we request a total of $270,000, $120,000 and $120,000, respectively. These funds would be directly transferred to Dr. D. Wright, an adjunct professor at Dalhousie University.

Fiscal	Funding  Justification
Year	Request	

1995-96	$170,000 Purchase of a high speed IBM SP2 parallel
	         processor or equivalent machine
	$50,000  Full Support for one Scientific Computing 
	 	 Research Associate
        $40,000  Full Support for one Postdoctoral Research 
	$10,000	 Operating and media costs and travel

1996-97	$50,000  Full Support for one Scientific Computing
		 Research Associate
        $40,000  Full Support for one Postdoctoral Research
        $20,000  Partial Support for one Postdoctoral Research
	$10,000	 Operating and media costs and travel costs

1997-98	$50,000	 Full Support for one Scientific Computing
		 Research Associate
        $40,000  Full Support for one Postdoctoral Research
        $20,000  Partial Support for one Postdoctoral Research
	$10,000	 Operating and media costs and travel costs

Table 1: Itemized funding request to the Atmospheric Environment Service/Canadian Institute for Climate Studies for support of the regional ocean Canadian community modelling effort (CCME1).
The global ocean modelling work of Dr. A. Weaver at the University of Victoria is also central to the goals of the Canadian Climate Research Network. As discussed in section 2.2, a global model has now been coupled to the Canadian Climate Centre Atmospheric GCM. In order to benefit from the wide range of expertise within the Canadian oceanographic community, Dr. Weaver will offer the global ocean model as a community model which will be run on his local work station cluster. The knowledge gained from this community modelling effort will assist in the development of the next generation of global ocean models for coupling to future generations of the CCC atmospheric model.

The direct funding request for CCME2 is detailed in Table 2 below. Dr. Weaver currently receives $25,000 per year in infrastructure support (#11 CICS - Global Oceans) which assists him in actively collaborating with the AES to develop and run coupled atmosphere-ocean-ice general circulation models. We are applying for an extension of this contract (#11 CICS - Global Oceans) and an additional $40,000 in each of the 1995-96, 1996-97 and 1997-98 fiscal years. These funds would be directly transferred to Dr. A. Weaver at the University of Victoria and are independent of his attached research grant proposal.

Fiscal	Funding	Justification
Year	Request	

1995-96	$30,000	Partial support for one Scientific Computing 
		Research Associate
	$10,000	Operating and media costs
	$25,000	Continuation of #11 CICS — Global Oceans
		contract for infrastructure support

1996-97	$30,000	Partial support for one Scientific Computing
		Research Associate
	$10,000	Operating and media costs
	$25,000	Continuation of #11 CICS — Global Oceans
		contract for infrastructure support

1997-98	$30,000	Partial support for one Scientific Computing
		Research Associate
	$10,000	Operating and media costs
	$25,000	Continuation of #11 CICS — Global Oceans
		contract for infrastructure support

Table 2: Itemized funding request to the Atmospheric Environment Service/Canadian Institute for Climate Studies for support of the global ocean Canadian community modelling effort (CCME2).

6. Management Structure

As a large scientific study composed of teams of interdisciplinary scientists, WOCE requires active project management. Our philosophy is to minimize this management function, yet maximize the effectiveness of the entire program. The management of our project began with the call for Letters of Intent in December, 1993, and will continue through to the end of the funding cycle.

The present CNC WOCE committee will steer the formation of the next proposal but will then reform to be composed primarily of Principal Investigators (PIs). A small independent Screening Committee will be formed to conduct the scientific reviews of the proposals. This Screening Committee will only exist through the summer of 1995. Their primary task will be to generate scientific reviews of the proposals. At their dissolution, they will prepare a report summarising the reviews and suggest names for international experts to sit on the Scientific Advisory Committee (discussed below). The PIs will also be asked to suggest names of scientists who should sit on the Scientific Advisory Committee.

The Scientific Advisory Committee (SAC) will be made up of international scientists to provide input and reviews on the state and progress of the Canadian WOCE science program. The SAC will be particularly helpful in assessing the progress of the science throughout the life of the project. Members of the SAC will be invited to the annual workshops of WOCE which will be held for all investigators in the program. The first annual report of WOCE will not be peer reviewed, but will be sent from CNC WOCE to NSERC, the Canadian National Committee for Climate Research (CNCRC) and the Canadian Institute for Climate Studies (CICS). It is felt that there would not be enough progress made to warrant an international peer review at the end of the first year. Reports in following years will be sent to the Scientific Advisory Committee whose reviews will be attached and sent to NSERC, CNCRC and CICS together with the annual reports themselves.

After the initial cycle of proposal peer review and funding authorization, CNC WOCE will be restructured to represent the PIs. The role of the revised CNC WOCE will be to: a)- organize an annual workshop for all investigators; b)- request and organize annual reports on the progress of science; c)- determine the funding levels of projects. From the perspective of the funding agencies (NSERC, DFO, AES/CICS), CNC WOCE serves to make sure the program stays on track. Thus the committee is expected to respond to any major problems that come up and to adjust the program and funding levels appropriately. From the perspective of the scientists, the committee serves to organize the workshops, stimulate communication and to assure the funding agencies that excellent and timely science is being accomplished.

CNC-WOCE is also the governing body for the WOCE secretariat, which reports annually to the WOCE International Project Office, and to the various overview bodies and committees (DFO National Climate Committee, NSERC, the Research Committee of the Canadian Climate Board, CNC-SCOR, CNC-WCRP, CGCP).

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