climate.uvic.ca

CCAF2 Project # : S02-13-01

PROJECT TITLE: The effect of Arctic Ocean processes on global climate change

PRINCIPAL INVESTIGATOR(S): A. J. Weaver

COLLABORATOR(S): O. A. Saenko and M. Eby

REPORT AGAINST PROJECT GOALS AND DELIVERABLES (for period ending December 31, 2002):

We have further elaborated on 1) improving a representation of subgrid-scale processes in our climate model and on 2) developing diagnostics for heat uptake by the ocean in our global warming experiments. Items 1 and 2 are briefly outlined below.

1) We focused on two issues. First, we found an optimal set of parameters for our bottom boundary parameterization to more realistically simulate density-driven downsloping flows in our model. These flows arise in regions of dense water formation and, in particular, in polar and subpolar regions. Figure 1 shows spatial distribution and magnitudes of the simulated density-driven downsloping flows in our model. Second, work towards a new model configuration has been initiated. The new model will have higher resolution in both horizontal and vertical directions, including better representation of the Arctic Ocean. Figure 2 shows the global ocean elevation for the model configuration with higher resolution in zonal and vertical directions. Sensitivity experiments are underway to adjust parameters and to compare the CO2-induced climate response between the two model configurations.

2) One of the key parts of our investigation is to understand what processes control an uptake and vertical propagation of heat within the ocean under the CO2-induced global warming (Figure 3). To accomplish this, we have developed a set of heat budget diagnostics to analyze the results from the sensitivity experiments outlined in our previous report. A draft of the paper is now in preparation, where the key results from these CO2-forced sensitivity experiments will be outlined.

In addition, we have performed a study (supported in part by the CCCAF) on the sensitivity of deep water formation in the Northern Hemisphere to the surface density range (see reference below). The study shows a close link between processes determining stability of deep water formation in the Northern and Southern Hemispheres.

References:

Saenko, O. A. and Weaver, A. J., 2003: Southern Ocean upwelling and eddies: sensitivity of the global overturning to the surface density range. Tellus, 55A, 106-111.

ANY COMMENTS OR CONCERNS ON STATE OF PROGRESS: None

PREPARED BY: A. J. Weaver

DATE: February 10, 2003


Fig. 1: The vectors show a spatial distribution and magnitudes of the density-driven downsloping flow due to a simple bottom boundary parameterization.


Fig. 2: Ocean bottom topography and elevation in a model version with higher resolution in zonal and vertical directions.


Fig. 3: Zonally-averaged section of temperature difference showing heat uptake by the ocean at time of CO2 doubling in the atmosphere.


UVic / SEOS / Climate Group / Research Funding / CCAF Weaver, Saenko, Eby Last updated: Wednesday, 23-Apr-2003 10:10:47 PDT