Dennis McGillicuddy, Daniel Lynch, Peter Wiebe, Jeff Runge, Wendy Gentleman and Cabell DavisA set of observational system simulation experiments (OSSEs) have been designed to quantitatively measure the ability to reconstruct spatial and temporal variations of populations on Georges Bank and its environs with the broad-scale mapping strategy used in the GLOBEC program. The approach makes use of a model simulation which contains realistic spatial and temporal fluctuations of adult Calanus females observed during February and March 1995. The simulation is constructed with an adjoint data assimilation procedure which is used to dynamically interpolate between the two broad-scale surveys taken one month apart. This simulation is then subsampled in space and time along a typical cruise track. These simulated data are then objectively analyzed and the resulting maps compared with "reality" as represented in the original simulation. Results from this particular example indicate total error on the order of 20% which is comprised of roughly equal contributions from simple mapping error and spatio-temporal smearing.