The progress report below has been partitioned into subcategories representing the research done by MSc and PhD students and Research Associates working under my supervision. In addition, I have also outlined my own research projects. I have chosen to write this year's progress report in this format as it emphasizes the Training of Highly Qualified Personnel. This progress report and the original WOCE proposal may be viewed on the world wide web at:
In her thesis Ms. Wohlleben examined the statistical relationships between various components of the subpolar North Atlantic air-sea-ice climate system in order to investigate potential processes involved in interdecadal climate variability. It was found that sea surface temperature anomalies concentrated in the Labrador Sea region have a strong impact upon atmospheric sea level pressure anomalies over Greenland, which in turn influence the transport of freshwater and ice anomalies out of the Arctic Ocean, via Fram Strait. These freshwater and ice anomalies are advected around the subpolar gyre into the Labrador Sea affecting convection and the formation of Labrador Sea Water. This has an impact upon the transport of North Atlantic Current water into the subpolar gyre and thus, also upon sea surface temperatures in the region.
An interdecadal climate feedback loop was therefore proposed as an internal source of climate variability within the subpolar North Atlantic. Through the lags associated with the correlations between different climatic components, observed horizontal advection timescales, and the use of Boolean Delay Equation models, the timescale for one cycle of this feedback loop was determined to have a period of about 21 years.
The results of this work ( Wohlleben and Weaver, 1995 ) have recently been accepted for publication in Climate Dynamics. While NSERC/WOCE funds were not explicitly used to pay the salary of Ms. Wohlleben they were used to provide operating support in the form of: publication charges, telephone, fax, xeroxing, computer hardware and software support (both via direct hardware/software acquisition costs and through indirect costs via the salaries to computer systems managers and maintenance contract charges). Ms. Wohlleben will also be presenting the results of this work at the upcoming 29th annual CMOS Congress.
Dr. Reynaud's PhD research involved the use of archived temperature and salinity data from the Labrador Sea region of the North Atlantic. He developed a new method of objective analysis to yield a high resolution (1/3 degree x 1/3 degree) data set for use in diagnostic studies. The data set was then partitioned into seasons and diagnostic studies were done using a variety of techniques (Bernoulli method - Killworth, 1986; Depth of no motion method; Mellor et al. method - Mellor et al., 1982). Through this research we obtained a high resolution analysis of the circulation of the Labrador Sea.
Two articles have been written from this thesis. In the first of these (Reynaud et al. 1995a) we analysed the climatological mean summer circulation and water mass properties (CWMP) in the Labrador Sea. In the second paper (Reynaud et al. 1995b - written but not yet submitted as Dr. Reynaud is on a WOCE cruise in the South Atlantic), we have extended this analysis to examine interdecadal changes in the CWMP. A final manuscript is being written concerning the seasonal variability of the CWMP.
Results from the first chapter of her thesis were published last year (Hughes and Weaver, 1994) and discussed in last year's NSERC/WOCE annual report. A second chapter explored the role of the sea surface temperature - evaporation feedback for the ocean's thermohaline circulation; this work has recently been submitted ( Hughes and Weaver, 1995 ). Briefly, a positive feedback is found whereby the overturning circulation warms the high latitudes through advection, increasing the latent heat loss and raising the sea surface salinity, which then feeds back on to the overturning. The magnitude of the time-dependent component of the evaporation is quite small however, which tends to support the use of fixed freshwater fluxes as a good first approximation to air-sea interaction. In agreement with this, two examples with internal variability of the thermohaline circulation on decadal and millennial timescales were studied. The variability was not fundamentally altered under the new feedback compared to control runs under "mixed boundary conditions", although both the period and the duration of the variability were shortened in some cases. Early results from this project were presented at an invited lecture at the Spring Meeting of the AGU in Baltimore, and the completed research will be presented at the CMOS Annual Congress this spring.
The remainder of Dr. Hughes' thesis described the development of a global ocean model with realistic geography and topography. The climatology of the model under annual mean forcing (observed winds, restoring to Levitus surface temperature and salinity) was assessed as the basis for a comparison with the equilibrium circulation under diagnosed heat, freshwater and momentum fluxes from the Canadian Climate Centre 2nd generation atmospheric general circulation model. The pronounced drift of this equilibrium away from the observed global ocean circulation led to the suggestion of a new method of flux correction for use in coupled atmosphere-ocean GCMs. This research will be discussed further in section 4.4 below.
Finally, Dr. Hughes was involved in a collaboration with D. Wright (Bedford Institute) and C. Vreugdenhil (Netherlands) to compare the dynamics of zonally-averaged and three-dimensional ocean circulation models, with the goal of improving the parameterisation of zonal pressure gradients necessary in the former. This work will appear in print shortly (Wright et al., 1995)
P. Myers' PhD research has been in the area of finite element modelling/model development. The finite element method possesses many advantages over more traditional numerical techniques used to solve systems of differential equations. These advantages include a number of conservation properties and a natural treatment of boundary conditions. The method's piecewise nature makes it useful when dealing with irregular domains, and similarly when using variable horizontal resolution. To take advantage of these properties, a finite element representation of the linearized, steady-state, barotropic potential vorticity equation has been developed. A working version of the barotropic model now exists in both Cartesian and spherical coordinates. Both versions have been rigorously tested against analytic solutions and against existing finite difference models. In all cases, the comparisons are extremely favourable. The description of this model will appear in the June issue of Journal of Atmospheric and Oceanic Technology ( Myers and Weaver, 1995 ).
The model was then used to study the separation of the Gulf Stream in the North Atlantic. The model's ability to incorporate variable spatial resolution allowed the simulation of the correct latitude of separation for the Gulf Stream with the inclusion of the JEBAR term (Joint Effect of Baroclinicity And Relief). Results suggest that the JEBAR term in three key regions (offshore of the separation point in the path of the main jet, along the slope region of the North Atlantic Bight and in the central Irminger Sea) is crucial in determining the separation point. The transport driven by the bottom pressure torque component of JEBAR dominates the solution, except in the subpolar gyre, and hence is responsible for the separation of the Gulf Stream. Excluding high latitudes (in the deep water formation regions) density variations in the upper 1000 m (thermocline region) of the water column govern the generation of the necessary bottom pressure torque in our model ( Myers et al., 1995 ).
Examination of results from the World Ocean Circulation Experiment Community Modelling Effort (WOCE-CME) indicates that the bottom pressure torque component of JEBAR is underestimated by almost an order of magnitude, when compared to our diagnostic results. The reason for this is unclear, but may be associated with the diffuse nature of the modelled thermocline in the CME as suggested by our model's sensitivity to the density field above 1000 m. In addition, Claus Boening at Kiel University is going to provide us with temperature and salinity fields from the WOCE CME to allow us to analyse their results more deeply.
A global version of this model is now operational. The model correctly handles the cyclical boundary conditions associated with the Antarctic Circumpolar Current. Work is presently ongoing to attempt to determine the barotropic circulation, including the JEBAR term, for the global ocean. The next step will then be to look at the effects of interpentadal changes in the density field on the overall circulation.
A time-dependent version of the model has also been developed. This model includes the nonlinear terms and an iterative solver. It is also in the process of being converted to run in spherical coordinates. As a quick test, the model will be applied to the North Atlantic, in an attempt to see what effect the non-linear terms have on the full circulation, including the JEBAR term. It is then hoped to use this model to examine the barotropic circulation in the North Pacific Ocean.
The development of a fully-prognostic, baroclinic, primitive equation ocean model is beyond the scope of Paul Myers' PhD. However, research will continue towards meeting this goal in collaboration with Dr. Rodolfo Bermejo at the Department of Applied Mathematics, University of Madrid, and Dr. Owen Walsh at CERCA, University of Montreal.
The resultant energy-moisture balance model (EMBM) has been run in a global 2 degree x 2 degree domain with fixed sea surface temperatures ( Fanning and Weaver, 1995 ). Under climatological oceanic conditions, the surface air temperatures, specific humidities and surface fluxes are comparable to direct estimates. As an extension to the climatological forcing case, a simple perturbation experiment was considered in which the 1955-59 pentad was compared to the 1970-74 pentad by driving the model under the respective sea surface temperatures. The model exhibits global, as well as basin-mean temperature changes in the latter pentad comparable to direct estimates (Jones, 1988).
The interpentadal modelled differences are quite robust. This effect was demonstrated by rerunning the model with parameters representative of several different unrealistic climatologies. The resulting interpentadal difference fields change remarkably little even when the background state has changed dramatically. Such a result appears to add convincing support for the use of flux corrections in coupled ocean-atmosphere modeling studies.
A version of the fully coupled ocean-atmosphere model (EMBM coupled to the GFDL-MOM) has been run in a single-hemisphere (60 degree x 60 degree) basin, driven by zonally uniform wind stress and solar insolation forcing. A series of several experiments of varying horizontal resolution (ranging from 4 degree x 4 degree to 1/4 degree x 1/4 degree) and viscosity have been conducted to assess the effect on the components of the net poleward heat transport. The model integrations are now complete, and we are currently analyzing the relative contributions of the mean and time variant components of the heat transport. These include the effects of the barotropic gyre transport (in the horizontal plane), the meridional overturning transport (in the zonal plane), the baroclinic gyre transport, as well as the eddy and diffusive heat transport components. An article on this work will be written up and submitted to Nature shortly.
In another project, A. Fanning is developing a double-hemisphere model representative of the Atlantic basin. This model incorporates a thermodynamic ice model (Semtner, 1976) (which includes heat insulation as well as brine rejection) into the coupled ocean-atmosphere model. This model will form the basis for a number of future studies. The first concerns whether multiple equilibria exist in an idealized coupled ocean-atmosphere model. Next we will investigate the causes for rapid climate variability during glacial-interglacial transitions, examining the roles of deglacial meltwater forcing as opposed to change in the solar insolation distribution.
In the first study ( Robitaille and Weaver, 1995 ), three sub-grid scale mixing parameterizations (lateral/vertical; isopycnal/diapycnal; Gent and McWilliams, 1990) were used in a global ocean model in an attempt to determine which yields the best ocean climate. Observations and model Freon 11 distributions in both the North and South Atlantic were used in the model validation. While the isopycnal/diapycnal mixing scheme does improve the deep ocean potential temperature and salinity distributions, when compared to results from the traditional lateral/vertical mixing scheme, the Freon 11 distribution is significantly worse due to too much mixing in the southern ocean. The Gent and McWilliams (1990) parameterization, on the other hand, significantly improves the deep ocean potential temperature, salinity and Freon 11 distributions when compared to both of the other schemes. The main improvement comes from a reduction of Freon uptake in the southern ocean where the "bolus" transport cancels the mean advection of tracers and hence causes the Deacon Cell to disappear. These results suggest that the asymmetric response found in CO2 increase experiments, whereby the climate over the southern ocean does not warm as much as in the northern hemisphere, may be an artifact of the particular mixing schemes used.
Dr. Jim McWilliams at UCLA recently visited us to discuss these results. We will continue to interact with him as the work progresses. In addition, Dr. Ray Weiss at Scripps Institute of Oceanography will collaborate on the Freon/model intercomparison as the research progresses.
D. Robitaille is following up this work with a detailed parameter sensitivity study using the three sub-grid scale mixing schemes mentioned above. He will compare the ocean general circulation model results with results from simple scaling analyses of the thermocline equations (in collaboration with Dr. Amit Tandon - see 4.4.4).
Another project has been to use apparent salinities as a restoring surface boundary condition on salinity in ocean general circulation models instead of climatological values. The usefulness of this method is under study using an ocean model of the North Atlantic.
D. Robitaille has also participated in the DFO CRV Ricker Cruise in September, 1994. The cruise was run by Dr. David Welch (Pacific Biological Station, Nanaimo, BC) and was designed to collect CTD, and plankton samples in the North Pacific Ocean.
In his research T. Huck is investigating the effect of various momentum dissipation parameterizations in thermohaline circulation models using the planetary geostrophic equations. The traditional Laplacian momentum dissipation used presently in most ocean general circulation models is based on a conservation law appropriate for small scale viscous processes. For the large scales considered by ocean general circulation models, it parameterizes the process of barotropic instability better than the process of baroclinic instability. We are trying to determine what the consequences of this choice of momentum parameterization are in terms of the boundary layer structure of the ocean circulation. To this end comparisons will be done with other parameterizations of dissipation (e.g. Rayleigh friction) in both hydrostatic primitive equation models and non-hydrostatic planetary geostrophic models.
A new three-dimensional ocean circulation model has been developed using diagnostic planetary geostrophic dynamics and fully prognostic equations for potential temperature and salinity. Horizontal momentum dissipation is parameterized by linear Rayleigh friction, and different methods are used to solve for the non-hydrostatic boundary layers. The results in idealised geometry are being compared to those obtained using traditional Laplacian dissipation and also using fully prognostic dynamical equations. The comparison is based on identical atmospheric forcing, in order to analyse the effect of only the parameterization change in each run. The structure of the boundary layers and the large-scale circulation will be compared, as well as the thermohaline variability, in order to improve the understanding of the mechanisms involved.
T. Huck, along with D. Robitaille, A. Fanning and A. Tandon attended the recent NATO Advanced Study Institute, Les Houches, France, February 13-24 on decadal climate variability.
To determine the extent to which the accuracy and efficiency of the calculations depended on the numerical integration scheme, the test problem was solved independently using an explicit finite difference (leap-frog in time, centered difference in space) method and three implicit methods: a finite difference, a finite element and an upwind scheme. Integrations of the model to several equilibria were performed to determine the accuracy, efficiency and stability of each integration scheme as a function of time step. For the same level of accuracy the time step used in the semi-Lagrangian scheme was found to be at least five times greater than that employed in the case of the implicit methods. The time step used in the implicit methods in turn were at least six times greater than those needed in the explicit integration of the governing equations. It was further shown that Dirichlet, Neumann and mixed boundary conditions could be handled efficiently with the semi-Lagrangian method. The semi-Lagrangian method was also applied in the usual three-time level and two-time level interpolating versions as well as in a non-interpolating, three-time level version. The two-time level scheme further doubled the speed of the time integration step for the same level of accuracy, beyond that which was achieved using the three-time level scheme. The non-interpolating scheme did not eliminate the damping introduced by the interpolation. Hence we concluded that the two-time level semi-Lagrangian advection method was best suited for ocean climate studies. These results are detailed in Das and Weaver (1995) .
An interesting phenomenon which I observed in Weaver (1993) was that for different equilibria obtained under normal, 2xCO2, 4xCO2 and 8xCO2 forcing in coupled GCMS (and indeed in the uncoupled Canadian Climate Centre atmospheric GCM), the total planetary heat transport was fairly constant (in a global warming or cooling scenario there was net heat loss or gain by the planetary system but at equilibrium, the radiation balance at the top of the atmosphere was similar). This phenomenon was exploited in the coupled atmosphere-ocean box model developed by Tang and Weaver (1995a) . The results of this simple coupled model suggest, as did the uncoupled ocean experiments of Weaver and Hughes (1994) , that if the earth were to warm by a few degrees then we might expect rapid climate variability as seen in the last interglacial period.
In the past year, Dr. Tang has also been working on a two-dimensional model. He is using the model to study the stability of equatorially symmetric circulations. Symmetric circulations were found to be unconditionally unstable by Marotzke et al (1988), but were found to be stable in Saravanan and McWilliams (1995). In an effort to sort out this confusion, Dr. Tang has found that two parameters - the horizontal diffusivity and the relative importance of haline and thermal forcing - determine the stability of the symmetric circulations. Dr. Tang has worked out stability threshold diagrams for both the thermally dominant and the haline dominant symmetric circulations, both of which have distinct stability properties. It was also found that at low resolution, the stability of symmetric circulations depends on whether the number of meridional grid points is odd or even; unconditional instability of a thermally dominant circulation occurs when a grid point is on the equator and horizontal diffusion is absent. The stability of the pole-to-pole circulation in the model is also being studied. These results will be submitted for publication shortly (Tang and Weaver, 1995b).
This global ocean model has also been given to Prof. Bill Gough at the University of Toronto, to initiate a collaboration on the influence of spurious cross-isopycnal mixing due to lateral diffusivity in regions of sloping isopycnals (the "Veronis effect"). T. Hughes visited Toronto in March, 1995 for this purpose.
Over the last 2 years I have been working on a detailed scaling analysis of the thermohaline circulation under both Neumann and Dirichlet boundary conditions. This scaling analysis is being compared with the results of a "converted GFDL general circulation model". That is, the normal GFDL code has been stripped to be purely baroclinic (the barotropic mode is zero as there is no wind forcing, nonlinear terms in the momentum equation, bottom friction or topography. Hence all this code has been removed). Furthermore, the tracer and salinity equations have been combined into one "conservation of potential density" equation so that there is no equation of state. Finally, Dirichlet boundary conditions have been implemented directly instead of using the more normal relaxation boundary condition.
Dr. Tandon is extending this research by more closely analysing boundary layer processes and in particular the importance of the "Veronis effect" mentioned earlier.
In late 1994 I got together with Ed Boyle (a geochemist) at MIT to write a short piece for Nature (Boyle and Weaver, 1994) concerning multiple equilibria of the North Atlantic thermohaline circulation and paleoclimatic data from the last glacial maximum.
In a paper submitted to Climate Dynamics in January ( Weaver and Hughes, 1995 ), we showed that the magnitude of the mismatch between ocean general circulation model (OGCM) and atmospheric general circulation model (AGCM) fluxes is not as important for climate drift as the difference between OGCM and implied AGCM heat and freshwater transports. Hence a "Minimum Flux Correction" was proposed which is zonally-uniform in each basin and of small magnitude compared to present flux corrections. This minimum flux correction acts only to correct the AGCM implied oceanic transports of heat and freshwater. A slight extension was also proposed to overcome the drift in the surface waters when the minimum flux correction is used. Finally, we showed that the current methods used to determine flux corrections are all essentially equivalent leading to correction fields which are significantly larger than both AGCM and climatological fields over large regions.
Inspired by the success of the Minimum Flux Correction mentioned above, a separate experiment is underway. In this experiment we force the global ocean model with the newly-derived observed heat and freshwater fluxes over the ocean compiled by Da Silva et al. (1994). This fluxes have been tuned to constrain the zonally-integrated transports of both heat and freshwater toward observed estimates. The purpose of this project is to investigate new ways of spinning up OGCMs prior to coupling them with AGCMs.
Another project which is underway is an investigation of the importance of the seasonal cycle for the global thermohaline circulation. Preliminary results under seasonal sea surface temperatures and salinities show an intensification of the North Atlantic overturning circulation by > 3 Sv, which is accompanied by a cooling of the upper ocean and warming of the deep ocean in all three basins of the world ocean (Atlantic, Indian, Pacific). The Antarctic Circumpolar Current also warms significantly, although these changes appear (upon cursory inspection) to be driven by the Mediterranean. A next step will be to permit the winds to also vary seasonally.
I also worked collaboratively with Warren Lee in the Canadian Climate Centre (CCC) to develop a high-resolution global ocean model which has now been coupled to the CCC AGCM for the purpose of undertaking climate change/variability forecasts. I have a strong collaboration with the CCC and am the Scientific Leader of their Ocean Modelling effort. We now have a fully coupled atmosphere/ocean/ice model available and we are presently examining ways of reducing the flux correction which must be incorporated.
da Silva, A. M., C. C. Young and S. Levitus, 1995: Atlas of Surface Marine Data 1994, Volume 1: Algorithms and Procedures. NOAA Atlas NESDIS 7. In press.
Gent, P. R. and J.C. McWilliams, 1990: Isopycnal mixing in ocean circulation models. J. Phys. Oceanogr., 20, 150-155.
Jones, P.D., 1988: Hemispheric surface air temperature variations: Recent trends and an update to 1987. J. Climate, 1, 654-660.
Killworth, P.D., 1986: A Bernoulli inverse method for determining the ocean circulation. J. Phys. Oceanogr., 16, 2031-2051.
Lenderink, G., and R.J. Haarsma, 1994: Variability and multiple equilibria of the thermohaline circulation associated with deep-water formation. J. Phys. Oceanogr., 24, 1480-1493.
Marotzke, J., P. Welander, and J. Willebrand, 1988: Instability and multiple steady states in a meridional-plane model of the thermohaline circulation. Tellus, 40A, 162-172.
Mellor, G.L., C.R. Mechoso and E. Keto, 1982: A diagnostic calculation of the general circulation of the Atlantic Ocean. Deep-Sea Res., 29, 1171-1192.
North, G.R., 1975: Theory of energy balance climate models. J. Atmos. Sci. 32, 2033-2043.
Pacanowski, R., K. Dixon and A. Rosati, 1993: The GFDL Modular Ocean Model Users Guide, GFDL Ocean Group Technical Report #2, 46pp.
Saravanan, R. and J. C. McWilliams, 1995: Multiple equilibria, natural variability, and climate transitions in an idealized ocean-atmosphere model. J. Climate, submitted.
Sellers, W.D., 1969: A global climatic model based on the energy balance of the earth-atmosphere system. J. Appl. Meteorol. 8, 392-400.
Semtner, A.J., 1976: A model for the thermodynamic growth of sea ice in numerical investigations of climate. J. Phys. Oceanogr., 6, 379-389.
Weaver, A.J., 1993: The oceans and global warming. Nature, 364, 192-193.
Weaver, A.J., J. Marotzke, P.F. Cummins and E.S. Sarachik, 1993: Stability and variability of the thermohaline circulation. J. Phys. Oceanogr., 23, 39-60.
2 This project was indirectly completed through a collaboration between Tertia Hughes and Dan Wright (Wright et al., 1995). We are extending this work as outlined in section 4.4.4.
3 As outlined in the last progress report we have decided not to include the semi-Lagrangian advection algorithms in the Bryan-Cox OGCM. Instead a non-hydrostatic thermocline equation model has been developed with frictional boundary layers (see section 4.3.2). We are currently investigating the implementation of semi-Lagrangian advection algorithms in this model. We must first examine methods for parameterizing convection which occurs on much faster timescales than the timestep in the semi-Lagrangian algorithms.
4 This project has been replaced by the ocean model validation project using WOCE Freon data (see section 4.2.5). This new project is more central to the goals of international WOCE.
5 A global, barotropic model has been developed as outlined in section 4.2.3. This project will continue in collaboration with O. Walsh and R. Bermejo once Paul Myers has received his PhD (see the end of section 4.2.3).
6 We have coupled a simple thermodynamic ice model to the OGCM as outlined in section 4.2.4. In addition, a thermodynamic ice model has been used in the coupled AOGCM used in the CCC (see section 4.5). Since there were problems in specifying boundary conditions above ice, we decided it was best to proceed with the fully coupled models.
2. Hughes, T.M.C. and A.J. Weaver, 1994: Sea surface temperature - evaporation feedback in an uncoupled model of the ocean's thermohaline circulation. Lecture presented at the 1994 Spring Meeting of the American Geophysical Union, Baltimore, Maryland, May 23-27.
3. Hughes, T.M.C. and A.J. Weaver, 1995: On the importance of the sea surface temperature-evaporation feedback for the ocean's thermohaline circulation. Lecture to be presented at 29th Annual Congress of the Canadian Meteorological and Oceanographic Society, Kelowna, British Columbia, May 30-June 2.
4. Fanning, A.F. 1994: An atmospheric energy-moisture balance model: Climatology and interpentadal climate change. Lecture presented at the University of Victoria, Victoria, B.C., Canada, December 2.
5. Fanning, A.F. 1994: An atmospheric energy-moisture balance model: Climatology and interpentadal climate change. Lecture presented at the Memorial University of Newfoundland, St. John's, Newfoundland, Canada, December 22.
6. Fanning, A.F., and A.J. Weaver, 1995: An atmospheric energy-moisture balance model: Formulation and Climatology. Lecture presented at the NATO Advanced Study Institute, Les Houches, France, February 13-24.
7. Fanning, A.F., and A.J. Weaver, 1995: A coupled ocean-atmosphere model for climate studies. Lecture to be presented at the 29th Annual Congress of the Canadian Meteorological and Oceanographic Society, Kelowna, British Columbia, May 29-June 2.
8. Myers, P.G., 1994: On the cause of Gulf Stream separation in ocean models. Lecture presented at the Institute of Ocean Sciences, Sidney, British Columbia, November.
9. Myers, P.G., 1994: On the cause of Gulf Stream separation in ocean models. Lecture presented at the School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia, November.
10. Myers, P.G., and A.J. Weaver, 1995: JEBAR, bottom pressure torque and Gulf Stream separation. Lecture to be presented at the 29th Annual Congress of the Canadian Meteorological and Oceanographic Society, Kelowna, British Columbia, May 29-June 2.
11. Robitaille, D.Y., 1995: Comparison of different mixing schemes in a general ocean circulation model. Lecture presented at the School of Earth and Ocean Sciences, University of Victoria, BC, Canada, February.
12. Robitaille, D.Y., 1995: Comparison of different mixing schemes in a general ocean circulation model with some Freon-11 data. Lecture presented at the NATO Advanced Study Institute, Les Houches, France, February 13-24.
13. Robitaille, D.Y., 1995: On the use of chlorofluorocarbons in ocean modelling. Lecture presented at the School of Earth and Ocean Sciences, University of Victoria, BC, Canada, March.
14. Robitaille, D.Y., and A.J. Weaver, 1995: Sensitivity of an ocean model to sub-grid mixing schemes. Lecture to be presented at the 29th Annual Congress of the Canadian Meteorological and Oceanographic Society, Kelowna, British Columbia, May 29-June 2.
15. Lee, W.G. and A.J. Weaver, 1995: An OGCM for coupling to the CCCMA AGCM. Lecture to be presented at the 29th Annual Congress of the Canadian Meteorological and Oceanographic Society, Kelowna, British Columbia, May 29-June 2.
16. LeBlond, P.H., A.J. Weaver and J.R.N. Lazier, 1995: Can runoff regulation in Hudson Bay really affect the climate of the North Atlantic? Lecture to be presented at the 29th Annual Congress of the Canadian Meteorological and Oceanographic Society, Kelowna, British Columbia, May 29-June 2.
17. Huck, T., A. Colin de Verdière and A.J. Weaver, 1995: The effect of momentum dissipation parameterizations in thermohaline circulation models using the planetary geostrophic equation. Lecture to be presented at the 29th Annual Congress of the Canadian Meteorological and Oceanographic Society, Kelowna, British Columbia, May 29-June 2.
18. Huck, T., 1995: On a thermohaline circulation model using planetary geostrophic equations with Rayleigh friction. Lecture presented at the School of Earth and Ocean Sciences, University of Victoria, British Columbia, Canada, March.
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2. Hughes, T.M.C. and A.J. Weaver, 1994: Multiple equilibria of an asymmetric two-basin ocean model. Journal of Physical Oceanography, 24, 619-637.
3. Weaver, A.J., Aura, S.M., and P.G. Myers, 1994: Interdecadal variability in a coarse resolution North Atlantic model. Journal of Geophysical Research, North Atlantic Deep Water Formation: Observation and Modeling Special Edition, 99, 12,423-12,441.
4. Boyle, E and A.J. Weaver, 1994: Conveying past climates. Nature, 372, 41-42.
5. Reynaud, T.H., Weaver, A.J. and Greatbatch, R.J. 1995a: Summer mean circulation in the western North Atlantic. Journal of Geophysical Research., 100, 779-816.
6. Myers, P.G. and A.J. Weaver, 1995: A diagnostic barotropic finite element ocean circulation model. Journal of Atmospheric & Oceanic Technology, 12, 511-526.
7. Weaver, A.J., 1994: Decadal-millennial internal oceanic variability in coarse resolution ocean general circulation models. In: The Natural Variability of the Climate System on the 10-100 Year Time-Scales, National Academy Press, in press.
8. Tang, B., and A. J. Weaver, 1995a: Climate stability as deduced from an idealized coupled atmosphere-ocean model. Climate Dynamics, in press.
9. Das, S.K. and A.J. Weaver, 1995: Semi-Lagrangian advection algorithms for ocean circulation models. Journal of Atmospheric & Oceanic Technology, in press.
10. Wohlleben, T., and A.J. Weaver, 1995: Interdecadal climate variability in the subpolar North Atlantic. Climate Dynamics, in press.
11. Grassl, H., F. Giorgi, A. Kattenberg, G.A. Meehl, J.F.B. Mitchell, R.J. Stouffer, T. Tokioka, and A.J. Weaver, 1996: Climate models - Projections of future climate. Chapter 6 of the 1995 Second IPCC Scientific Assessment. Ed. Sir J. Houghton, in press.
12. Gates, L., A. Henderson-Sellers, G. Boer, C. Folland, A. Kitoh, B. McAvaney, F. Semazzi, N. Smith, A.J. Weaver and Q.-C. Zeng, 1996: Climate models - validation. Chapter 5 of the 1995 Second IPCC Scientific Assessment. Ed. Sir J. Houghton, in press.
13. Weaver, A.J., and C. Green, 1995: Global climate change/variability: Action or adaptation to increasing greenhouse gases? - Lessons from the past. Science and Public Policy, submitted.
14. Myers, P.G., A.F. Fanning and A.J. Weaver, 1995: JEBAR, bottom pressure torque and Gulf Stream separation. Journal of Physical Oceanography, submitted.
15. Fanning, A.F., and A.J. Weaver, 1995: An atmospheric energy moisture-balance model for use in climate studies. Journal of Geophysical Research, submitted.
16. Weaver, A.J., and T.M.C Hughes, 1995: Flux corrections in coupled ocean-atmosphere models. Climate Dynamics, submitted.
17. Hughes, T.M.C. and A.J. Weaver, 1995: Sea surface temperature - evaporation feedback and the oceanÕs thermohaline circulation. Journal of Physical Oceanography, submitted.
18. Robitaille, D.Y. and A.J. Weaver, 1995: Validation of sub-grid scale mixing schemes using CFCs in a global ocean model. Geophysical Research Letters, submitted.
2. Tang, B. and A.J. Weaver, 1995b: Stability and variability of the thermohaline circulation in two-hemisphere ocean models. To be submitted to Journal of Geophysical Research.
2. Wright, D.G., C.B. Vreugdenhil and T.M.C. Hughes , 1994: Vorticity dynamics and zonally averaged ocean circulation models. J. Phys. Oceanogr. in press.
3. Reynaud, T. , 1994: Dynamics of the Northwestern Atlantic Ocean. PhD Thesis, Department of Atmospheric and Oceanic Sciences, McGill University, Montreal, Canada, 267 pp.
4. Wohlleben, T.M.H. , 1995: Decadal Climate Variability in the Subpolar North Atlantic. MSc Thesis, School of Earth and Ocean Sciences, University of Victoria, 168pp.
5. Robitaille, D.Y. , L.A. Mysak, and M.S. Darby, 1995: A box model study of the Greenland Sea, Norwegian Sea, and Arctic Ocean. Clim. Dyn., 11, 51-70.
2. Lardner, R.W. and S.K. Das , 1994: Optimal estimation of eddy viscosity for a quasi-three-dimensional numerical tidal and storm surge model. Int. J. Num. Meth. Fluid., 18, 295-312.
3. Tang, B. , 1995: Periods of linear development of the ENSO cycle and POP forecast experiments. J. Clim., 8, 682-691.
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Operating: $120,000 NSERC Category 07/93-03/94 04/94-05/94 Carryover/use Proposed new funds a) Salaries 30,000 0 0 40,000 b) Tech. & Prof. Assistants 4,000 1000 0 5,000 c) Postdocs 6,000 5,000 0 35,000 d) Grad. students 20,000 4,000 0 30,500 e) Other 0 0 0 0 f) Equipment Purchase 25,000 0 0 0 Equipment Maintenance 9,000 0 0 6,000 g) Materials and Supplies 1,000 0 0 2,500 h) Computing and stats cost 0 0 0 0 i) Travel 5,000 0 0 4,000 j) Res. Manag. 0 0 0 0 k) Others (Page Charges) 10,000 0 0 5,000 --------------------------------------------------------------------------------------------------- TOTAL 110,000 10,000 0 128,000