An operational modeling implementation for the Trinidad-Venezuela region using feature models

Southeast of the Trinidad-Venezuela region, the North Brazil Current (NBC) retroflects and forms about 5-8 rings annually. In addition to the NBC rings being the most prominent dynamic feature after the retroflection, the shelf flow plays an important role in the regional circulation. We present a recent implementation of an operational modeling system for this region using the feature oriented regional modeling system (FORMS) methodology for the NBC rings and shelf flow. A new formulation of the ring is presented in which the synoptic structures of temperature and salinity profiles are placed at the core and the climatological profiles are placed around the edge. The shelf-break front is feature modeled by interpolating between a representative temperature profile on the shelf and the monthly climatology 200 km offshore of the coastline. The feature oriented scheme is used to initialize an operational forecasting system using the Harvard Ocean Prediction System (HOPS) framework. Three case studies between 2011 and 2012 are presented, wherein real drifter's trajectories within several NBC rings and the shelf are compared with those of the model drifters. These examples highlight the advantages of using feature models for short-term operational forecasting, in that, changing ring size and center location, changing level of no motion (LNM) and using drifter data for shelf flow verification allow for better predictability for the 4-5 days forecasts. These capabilities could be extended operationally to provide 2-3 week outlooks to offshore industry in the future.