SIMULATION OF THE JAVA SEA USING AN OCEANIC GENERAL CIRCULATION MODEL
The Hybrid Coordinate Ocean Model (HYCOM) is used to simulate the Java Sea mean sea level, surface current and volume transport. The model (JSD, Java Sea Domain) is driven by the European Remote Sensing (ERS) satellite-derived and National Center Environmental Prediction (NCEP) wind stresses. The ERS-derived and NCEP wind speeds and stresses are compared to investigate the impacts of the different wind forcing data on the estimation of the Java mean sea level. The validation results illustrate that the simulated mean sea levels agree well with the tide gauge sea levels. The NCEP wind-driven JSD (called NJSD) model has correlation coefficients from 0.53 to 0.84 and root mean square errors (RMSE) of 47 mm to 76 mm. On the other hand, the ERS wind-driven JSD (Called EJSD) model has the correlation coefficients from 0.71 to 0.89 and RMSEs of 40 mm to 61 mm against tide gauge sea level, respectively. These validation results reveal that accuracy of the EJSD model is better than the NJSD model.
The relationship between the Java Sea zonal wind and volume transport is also investigated by using HYCOM. Due to the shallowness of the Java Sea, the volume transport is dominated by the wind, which is greatly different between ERS and NCEP. The Java Sea volume transport is directed eastward and westward during the northwest (October to March) and southeast (April to September) monsoons, respectively. The westerly and easterly ERS wind stresses in December and August are 0.01 N/m2 and 0.03 N/m2 higher than NCEP wind stresses, respectively. Moreover, the NCEP mean wind speed is 1.0 m/s and 2.5 m/s lower than ERS mean wind speed, during the northwest and southeast monsoons, respectively. Consequently, the Java Sea eastward volume transport simulated by the EJSD model is found to be larger than the one simulated by the NJSD model. The EJSD model-simulated Java Sea eastward and westward volume transports in December and August are 0.23 Sv and 0.30 Sv larger than the ones simulated by the NJDS model, respectively.