Real-Time Data Assimilative Modeling on Georges Bank

Abstract

Real-time oceanic forecasts were constructed at sea on Georges Bank during Spring 1999. Ship-and shorebased computations were combined to deliver daily 3day forecasts to shipboard scientists for interpreting observations and planning operations. Data assimilated included acoustic Doppler current profiler velocities, drifter trajectories, and taxa-specific plankton observations from a Video Plankton Recorder (VPR) system. Services provided included basic 3-D circulation forecasts, forecast positions of drifters, dye and zooplankton, and the advective adjustment of observations to produce synoptic maps. The results indicate that real-time, at-sea data assimilative modeling can provide valuable information services and can be deployed routinely, provided that networking among ships, instruments, and shore continues to improve. This paper summarizes the real-time modeling experience. Results of the larger effort including scientific data interpretation are being reported separately.

Model simulations of the Bay of Fundy Gyre: 2. Hindcasts for 2005–2007 reveal interannual variability in retentiveness

“…The skill of the hindcast simulations (Table 2, separation rate between simulated and observed drifters of 5.36 km d −1 ) was larger than previous estimates for other regions (Georges Bank, 3.4 km d −1 [ Lynch et al , 2001] and 2.4 km d −1 [ Aretxabaleta et al , 2005]; Maine Coastal Current, 1.8 km d −1 [ He et al , 2005]). An important factor to consider is the fact that each region has a significantly different circulation regime.…”

“…The data assimilative model structure, developed by the Dartmouth Numerical Methods Laboratory, followed the schematic flowchart given by Lynch et al [2001] as revised and completed by Lynch and Naimie [2002]. It has been successfully used for several studies of the Gulf of Maine [ Lynch and Naimie , 2002; Aretxabaleta et al , 2005; He et al , 2005].…”

Barotropic tides in the South Atlantic Bight

“…Numerical solutions in the western North Atlantic Ocean are computed using ADCIRC‐2DDI [ Luettich et al , 1992] which solves the vertically integrated, fully nonlinear shallow‐water wave equations on linear triangular finite elements. This model is used in tidal simulations, storm surge calculations, and sediment transport studies, as well as in the operational oceanographic context [ Lynch et al , 2001; Blanton , 2003]. We use a standard quadratic bottom friction formulation with a drag coefficient of C d = 0.003 and a minimum depth of 4.0 m. The model domain (Figure 2) extends westward from the only open boundary (60°W) and includes the Gulf of Mexico as well as a high‐resolution representation of the ETIC along the coasts of Georgia, South Carolina, and North Carolina.…”

Model simulations of the Bay of Fundy Gyre: 1. Climatological results

“…[9] The Quoddy model [Lynch and Werner, 1991] used in these simulations has been widely applied in the Gulf of Maine and adjacent areas [Lynch et al, 1996[Lynch et al, , 1997[Lynch et al, , 2001Naimie, 1996;Proehl et al, 2005;He et al, 2005]. Quoddy is a three-dimensional, fully nonlinear, prognostic, tideresolving, finite element model.…”