Climate Modelling Group
School of Earth and Ocean Sciences
TECHNICAL PROGRESS REPORT
to Scripps Institution of Oceanography
for NOAA OFFICE OF GLOBAL PROGRAMS

Subcontractor: University of Victoria

SEMI-ANNUAL REPORT PERIOD: September 1, 1996 through August 31, 1997

Agency: National Oceanic and Atmospheric Administration, Office of Global Programs

Project Title: The Lamont/Scripps Consortium for Climate Research - Dynamical Modeling of Climate Change.

NOAA Award No: NA47GP0188

Principal Investigator: Andrew Weaver

Project Period: May 1, 1994 through August 31, 1997

Budget Period: September 1, 1996 through August 31, 1997

Performance Report Completed: October 22, 1997


Below I summarize the progress on the research funded through the NOAA Lamont/Scripps Consortium for Climate Research. In the 1997 calendar year the NOAA research grant funded, either wholly or partially, 11 papers (submitted, in press or appeared). I have strayed from my usual format of a progress report and will briefly describe the results from each paper.

1. Myers, P.G. and A.J. Weaver, 1997: On the circulation of the North Pacific Ocean: Climatology, seasonal cycle and interpentadal variability, Progress in Oceanography, 38, 1-49.
In this paper we developed and used a diagnostic model to examine the climatology and interpentadal variability of the barotropic circulation in the Pacific Ocean.

2. Murdock, T.Q., A.J. Weaver and A.F. Fanning, 1997: Paleoclimatic response of the closing of the Isthmus of Panama in a coupled ocean-atmosphere model. Geophysical Research Letters, 24, 253-256.
In this paper we used a locally-developed coupled atmosphere-ocean model to examine climatic response of the coupled climate system to the closure of the Isthmus of Panama.

3. Weaver, A.J. and M. Eby, 1997: On the numerical implementation of advection schemes for use in conjunction with various mixing parameterizations in the GFDL ocean model. Journal of Physical Oceanography, 27, 369-377.
In this paper we demonstrated some numerical problems which arose when the Gent and McWilliams parameterization for subgrid-scale mixing associated with mesoscale eddies was used in the GFDL MOM ocean model. We also showed how the flux-corrected transport advection scheme alleviated these problems.

4. Fanning, A.F. and A.J. Weaver, 1997: Temporal-geographical meltwater influences on the North Atlantic conveyor: Implications for the Younger Dryas, Paleoceanography, 12, 307-320.
In this paper we used a locally-developed coupled atmosphere-ocean model to examine the role of freshwater forcing (via continental ice sheet runoff) and the atmospheric wind feedback on the ocean's thermohaline circulation. This analysis was aimed at understanding the global response of the Younger Dryas event ~ 11 KBP.

5. Fanning, A.F. and A.J. Weaver, 1997: A horizontal resolution and parameter sensitivity study of heat transport in an idealized coupled climate model, Journal of Climate, in press.
In this paper we conducted a series of experiments to investigate the effect of horizontal resolution on poleward ocean heat transport (using both coupled and uncoupled ocean models). We found increasing poleward heat transport with increasing resolution up to 1/4deg. by 1/4deg.. We did not see a convergence of heat transport to this resolution. The increased heat transport with increasing resolution was due to a better resolution of the western boundary current.

6. Fanning, A.F. and A.J. Weaver, 1997: On the role of flux adjustments in an idealized coupled model. Climate Dynamics, in press.
In this paper we showed how global warming experiments which use flux adjustments tend to overestimate the climatic response in both transient and equilibrium cases.

7. Weaver, A.J. and S. Valcke, 1997. On the variability of the thermohaline circulation in the GFDL coupled model. Journal of Climate, in press.
In this paper we showed that the variability found by Delworth et al. in the GFDL coupled model was not an ocean mode and deduced that it was a mode of the full coupled system.

8. Fanning, A.F. and A.J. Weaver, 1997: Thermohaline variability: The effects of horizontal resolution and diffusion. Journal of Climate, in press.
In this paper we showed that as the resolution increased in ocean models decadal thermohaline variability could arise. We also showed that the horizontal diffusion parameter was the most important for suppressing the variability. The existence of decadal variability at high resolution was due to the ability of the numerical model to allow for smaller values of the horizontal diffusion to be used.

9. Huck, T., A.J. Weaver and A. Colin de Verdière, 1997: The effect of different parameterizations and boundary conditions applied to the momentum equation in coarse-resolution thermohaline circulation models. Journal of Physical Oceanography, submitted.
In this paper we examined the sensitivity of the thermohaline circulation to various boundary layer closures and boundary conditions.

10. Huck, T., A. Colin de Verdière and A.J. Weaver, 1997: Decadal variability of the thermohaline circulation in ocean models. Journal of Physical Oceanography, submitted.
In this paper we undertook a systematic and detailed parameter sensitivity analysis of the decadal variability found in coarse resolution ocean models. A simple box model was developed to explain the results.

11. Weaver, A.J., M. Eby, A.F. Fanning and E.C. Wiebe, 1997: The climate of the last glacial maximum in a coupled atmosphere-ocean model. Nature, submitted.
In this paper, a full coupled atmosphere-ocean-ice model was developed and used to examine the climate of the last glacial maximum. We found tropical SSTs which were significantly lower than those of CLIMAP.


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