A Study of the Distribution of 14 C in the Ocean Using a Two Dimensional Thermohaline Circulation Model
Xu Yongfu and Wang Mingxing (LAPC, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029) Jin Xiangze (LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences,Beijing 100080)
Oceanic carbon models often use radiocarbon to test the performance of the physical model for the large scale processes in the oceans. The physical model used in this work is a two dimensional thermohaline circulation model, including the Pacific, the Atlantic and the Southern Ocean. Under the forcing of given yearly mean temperature and salinity at the surface, the model is integrated over 4000 years to reach a quasi steady state. A constant flow field is used to drive tracer radiocarbon for the integration of over 5000 years until a steady state is reached. Seven numerical experiments are conducted by altering the values of vertical turbulent diffusivity and of the exchange coefficient of carbon dioxide between the atmosphere and the ocean. Using an exchange coefficient from Broecker et al.'s equation and the depth dependent vertical turbulent diffusivity which varies from 0.6 cm 2 ·s 1 at the surface to 1.45 cm 2·s 1 at the bottom layer, the modelled results are better. Using the observed time history of atmospheric radiocarbon content, the penetration of radiocarbon in the ocean is futher studied after industrialization and the test of nuclear weapons. The modelled results are compared with some observations, providing a reasonable agreement.
【CateGory Index】： P434