IMPLICATIONS FOR THE CREATION OF WARM SALINE DEEP-WATER - LATE PALEOCENE RECONSTRUCTIONS AND GLOBAL CLIMATE MODEL SIMULATIONS

A global warming trend began during the late Paleocene that culminated in the early Eocene with the highest global temperatures of the Cenoz oic, We have reconstructed late Paleocene surficial boundary condition s and modeled atmospheric conditions using the Goddard Institute for S pate Studies general circulation model version II (GISS GCM II). These experiments were conducted to test the hypothesis that warm saline de ep water formed during the late Paleocene and to understand atmospheri c circulation near the beginning of a period of global warming. The wa rming is attributed primarily to increased sea surface temperatures at high latitudes. The sensitivity of the climate to ocean temperature w as tested using two sea surface temperature distributions, each delimi ted latitudinally by oxygen isotope values, but with different east-we st gradients. The simulations discussed here contain several features unique among warm climate experiments. The first experiment (P-1) used latitudinally constant (zonal) sea surface temperatures, The zonally distributed sea surface temperatures strengthen the general circulatio n of the atmosphere. In particular, Hadley Cell circulation is intensi fied, leading to extremes of precipitation in the equatorial region an d extreme evaporation across subtropical oceans, The unusual results p rompted a second experiment with modern east-west sea surface temperat ure gradients superimposed and referred to as P-Gradient (P-Grad). The east-west gradients in the sea surface temperature field exert a stro ng influence on the general atmospheric circulation, but the extreme z onality prevails, Under extreme zonal conditions it is possible to cre ate a model where evaporation is in excess of precipitation by as much as 3 mm/day. If this occurred in restricted areas in a generally warm er ocean, such as the late Paleocene eastern Tethys Ocean and parts of the South Atlantic Ocean, it should be possible to create very saline water, which could become a component in warm saline deep water forma tion.