Prediction of the Gulf Stream path from upstream parameters

A linear Wiener (least squares optimal) filter is used to predict the path of the Gulf Stream in the region between Cape Hatteras and 70°W using upstream (“Inlet”) conditions as filter inputs. Although position, angle, curvature, geostrophic velocity, and curvature vorticity (κυ) measured at 73°W were tested as multiple Inlet parameters, it was found that Inlet position alone was the best predictor. With Inlet position as the predictor, this filter is equivalent to propagating meanders downstream with a typical phase speed and growth rate. Forecasts of the downstream path position are produced, more accurate than persistence, 12 days in advance at 140 km from the Inlet, 24 days in advance at 240 km from the Inlet, and 28 days in advance at 340 km from the Inlet.