Analysis of a Simulation of the Seasonal Cycle in the Tropical Pacific Ocean in an Eddy-Resolving Global Ocean Model.

摘要

This paper examines the multi-level, primitive equation, global ocean circulation model of Semtner and Chervin for its ability to simulate the seasonal cycle in the tropical Pacific Ocean. The result of a 20-year integration of this model using annual mean wind forcing was reported in Semtner and Chervin (1988). This was the first global eddy-resolving ocean calculation and it showed many realistic features of ocean circulation. The phase of the simulation analyzed in this report incorporates seasonally varying wind forcing from the Hellerman and Rosenstein (1983) global data set. These wind stress values were defined on a grid with 2 deg. spacing which have been interpolated to the one-half degree grid points of the Semtner and Chervin model. There is no interannual variability in the wind fields of this data set. The results presented here are from the fourth year of a 10-year seasonal cycle run. The upper oceanic circulation of the equatorial Pacific Ocean consists of alternating westward and eastward flows that vary seasonally in strength and extent. The eastward flows investigated in this study are the Equatorial Undercurrent and North Equatorial Countercurrent; the westward currents are the North and South Equatorial Currents. The Equatorial Undercurrent is most intense late in the Northern Hemisphere spring and is weak in the late fall at which time the North Equatorial Countercurrent and the South Equatorial Current are most intense. This result is in agreement with observations and other model studies.... Oceanographic Numerical Modeling, Pacific Ocean, Ocean General Circulation Model, Eddy-Resolving, Tropical, Equatorial Currents.