THE ROLE OF ALTERED INITIAL AND BOUNDARY CONDITIONS IN COUPLED GCM SIMULATIONS OF THE PLIOCENE CLIMATE

Simulations of the middle Pliocene climate are used to examine the effects of altered initial and surficial boundary conditions on the transient and equilibrium state of the warmer climates. The simulations employ a coupled dynamic ocean/atmosphere version of the GISS GCM at 4 x 5 degree horizontal resolution. Sensitivity tests are used to analyze the impact of changing boundary conditions including, ocean surface temperatures and sea ice cover, sea level and topographic relief, vegetation distribution, and land ice paleogeography. Additionally, we examine the role played by changing the initial state of the vertical and horizontal temperature profiles in the ocean in order to determine the effect of the ocean model's initiation state. Finally, 3-dimensional gridded data sets of paleo-ocean temperatures are used to initiate full Pliocene paleoclimate simulations in an attempt to simulate the middle Pliocene warm period using methods as near to the techniques used for simulating future global warming.