Marine Technology Society Publication 	
Title: 
	Modeling and Forecasting the Gulf Stream
Journal Title: 
	Oceanic and Atmospheric Nowcasting and Forecasting
Journal Issue: 
	Volume 25, Number 2, 1992
Author: 
	Tal Ezer, Dong-Shan Ko, and George L. Mellor
Guest Editor: 
	Don L. Durham, James K. Lewis
Abstract: 
	
Numerical simulations are performed to evaluate the forecast skill of a model of the 
Gulf Stream system.  The model is a high-resolution (eddy resolving) coastal ocean model, 
which includes thermohaline dynamics and a turbulence scheme to provide vertical mixing 
coefficients. In a series of forecast experiments, the model is initialized with synoptic 
temperature and salinity fields obtained form satellite and salinity fields obtained from 
satellite observations and the U.S. Navy’s Optimum observations and the U.S. Navy’s Optimum 
Thermal Interpolation System (OTIS). It then calculates the forecast fields (e.g., temperature, 
salinity, and sea surface height) for the next two weeks. In the three cases presented here, 
the model forecasts gave a better estimate of the model forecast of the ocean than did 
pesistence (i.e., the assumption of no change), showing a forecast skill for at least two 
weeks. Sensitivity studies demonstrate the effects of vertical grid resolution, horizontal 
diffusion, and smoothing on the forecast skill is improved with the vertical grid is 
refined and when smoothing or horizontal diffusion is large enough to remove small-scale 
spatial variations from the forecast fields; such variations are missing from the smoothed 
OTIS fields but may exist in the real ocean. The study shows that numerical models can be 
used to aid commercial and navy operations in forecasting oceanic fields; nevertheless, 
there are sill deficiencies in numerical models and difficulties in quantitative evaluation 
of the forecast skill of ocean models due to the sparse coverage of oceanic measurements.