A new census of North Brazil Current (NBC) rings for the period 1993-1998 has been
performed using the 1/16° global NRL Layered Ocean Model (NLOM) with data assimilation.
With assimilation of satellite altimeter data and high-frequency, interannual atmospheric
forcing, the 1/16° global NLOM is effectively a dynamic space and time interpolater of
the remotely-sensed data. TOPEX/POSEIDON altimeter data was assimilated into the model
from 1993 through May 1995. During the remainder of the time period of this study (June
1995 through 1998) both TOPEX/POSEIDON and ERS-2 altimeter data were assimilated.
The results were compared to the incongruous estimates of upper Atlantic meridional overturning cell (MOC) transport attributable to NBC eddies from two previous studies. Fratantoni et al. (1995) showed that a realistic, non-data-assimilating, climatologically- forced 1/4° North Atlantic version of NLOM realistically simulates NBC rings. They concluded that these rings carry approximately 20-25% of the upper Atlantic MOC transport. Goni and Johns (2001) in their analysis of TOPEX/POSEIDON satellite altimeter data from late 1992 through 1998 determined that these features may instead be responsible for more than 1/3 of the northward MOC transport.