Title: The relation between the Mindanao Current and Mindanao Undercurrent on seasonal scale

Journal: Acta Oceanologica Sinica, 35(5): 1-8

Authors: WANG Y., J. Lan*, and L. Li

Abstract:The ocean general circulation model for the earth simulator (OFES) products is applied to estimate the transports of the Mindanao Current (MC) and the Mindanao undercurrent (MUC) and explore the relation between them on seasonal scale. In general, the MUC is composed of the lower part of the Southern Pacific Tropical Water (SPTW) and Antarctic Intermediate Water (AAIW). While the deep northward core below 1 500 m is regarded as a portion of MUC. Both salinity and potential density restrictions become more reasonable to estimate the transports of MC/MUC as the properties of water mass having been taken into consideration. The climatological annual mean transport of MC is (37.4±5.81)×106 m3/s while that of MUC is (23.92±6.47)×106 m3/s integrated between 26.5σ θ and 27.7 σ θ, and (17.53±5.45)×106 m3/s integrated between 26.5 σ θ and 27.5 σ θ in the OFES. The variations of MC and MUC have good positive correlation with each other on the seasonal scale: The MC is stronger in spring and weaker in fall, which corresponds well with the MUC, and the correlation coefficient of them is 0.67 in the OFES. The same variations are also appeared in hybrid coordinate ocean model (HYCOM) results. Two sensitive experiments based on HYCOM are conducted to explore the relation between MC and MUC. The MUC (26.5< σθ <27.7) is strengthening as the MC increases with the enhancement of zonal wind field. It is shown, however, that the main part of the increasement is the deeper northward high potential density water (HPDW), while the AAIW almost remains stable, SPTW decreases, and vice versa.