TRANSIENT TRACERS IN A GLOBAL OGCM - SOURCE FUNCTIONS AND SIMULATED DISTRIBUTIONS

The global oceanic distributions of the transient tracers tritium, tri tiogenic He-3, and the chlorofluorocarbon CFC-11 (CFCl3) are modeled b y using the velocity field of the Hamburg Large Scale Geostrophic (LSG ) model. Source functions for these tracers are presented including th e extension of the global tritium source function from 1975 to 1995. T he tracer distributions are compared with observations. The sensitivit y of the tritium and CFC-11 simulations tb the variation of adjustable parameters in the source functions is determined. The adjustable sour ce function parameters cannot be varied to simultaneously achieve both a proper reproduction of the overall tracer inventories and the obser ved patterns of the tracer distributions. Further improvements are onl y possible through a change in the velocity field itself. Therefore an thropogenic tracers indeed provide a firm reality check for model ocea n velocity fields. The model is used to simulate the. future evolution of transient tracer fields for different oceanic regions until the ye ar 2050.