--> ABSTRACT: The Late Paleocene (Thanetian) Hydrological Cycle and Implications for the Creation of Warm-Saline Bottom Water: GISS GCM Simulations, by Suzanne O'Connell, Mark A. Chandler; #91020 (1995).

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The Late Paleocene (Thanetian) Hydrological Cycle and Implications for the Creation of Warm-Saline Bottom Water: GISS GCM Simulations

Suzanne O'Connell, Mark A. Chandler

During the late Paleocene (Thanetian) a global warming trend began which culminated during the early Eocene in the warmest global temperatures of the Cenozoic. We have modeled Thanetian atmospheric conditions using the Goddard Institute for Space Studies (GISS) GCM II.

Two different experiments were conducted, T-1, with latitudinally constant sea-surface temperatures (SST's) and T-2 with modern latitudinal SST gradients superimposed, suggesting modern oceanic circulation. Most striking was the strong zonality of all aspects of climate in T-1. All precipitation > 4 mm/day fell within 10°'s of the equator. The increase in precipitation was largest over land (7-13%), but the greatest amount of rain per unit area fell on the oceans. Nevertheless, over the ocean there was only a slight increase in precipitation in T-1 (3%), and a slight decrease in T-2 (-1%). The slight decrease over the oceans is surprising because supersaturated clouds and moist convective clouds both increased over modern values. Hence we attribute the decrease, at least in pa t, to lower storm activity because of the reduced meridional temperature gradient.

Evaporation rates were also higher, especially over land. Evaporation exceeded precipitation for many areas between 10° and 30° N and S latitude, including the Tethyan Basins in the restricted area between Africa and Asia. There evaporation exceeded precipitation by 4 mm/day making it an excellent location for the production of warm-saline bottom water.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995