Ocean, Ice, Atmosphere Seminar

Equatorial upwelling inferred from Helium isotope distributions

by
Prof. Monika Rhein
Department of Oceanography
Institute of Environmental Physics
University of Bremen

Upwelling is one of the key processes to maintain the Tropical Atlantic cold tongue. This feature is of special interest to climate research, since its SST variability is significantly correlated with the West African Monsoon. Direct measurements of the upwelling have been hampered by the small speeds involved. Instead, vertical motion has to be estimated by indirect methods. Here we propose a novel approach to infer equatorial upwelling velocities by exploiting the helium isotope disequilibrium between atmosphere and equatorial oceanic mixed layer. The data were collected during WOCE cruises A13 and A14. Although the vertical and horizontal resolution of the helium data in the upper tropical oceans was too poor to support a detailed study, it was sufficient to show the potential of the method.

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