동해남서부 Ulleung Interplain Gap을 통한 심층수 플럭스

Abstract

The East/Japan Sea (East Sea hereafter) is divided into three basins by submarine plateau and bank. For the climate of the East Sea, interbasin water exchanges are of fundamental importance due to the associated fluxes of heat and salt, which then determine the density of seawater and hence act as driving forces for the overturning circulation. Deep water formation takes place in the Japan Basin (JB) in the northern East Sea. Water masses below about 300 m in the JB consist of the Central Water, Deep Water (DW), and the Bottom Water (Kim et al., 1996). The DW lying between the CW and vertically homogeneous BW occupies a layer between 1800∼2500 m depths in the JB and its potential temperature is lower than 0.1℃ (Kim et al., 1999). The DW is also found in the Ulleung Basin in the southwestern East Sea below about 1500 m (Chang et al., 2002), which must originate from the JB since no source of deep cold water exists in the UB. The UB has no connection with the JB below 1500 m depth except through the Ulleung Interplain Gap (UIG), a deep (ca. 2,500 m deep and 75 km wide) passage between the UB and JB (Fig. 1). Attempts have been made to estimate the flux of the DW through the UIG because it is thought to be an important constraint on the circulation and diapycnal mixing in the UB. Chang et al. (2002) conjectured a net inflow of about 0.5 Sv into the UB through the UIG using data from a single mooring in the UIG, and Teague et al. (2004) estimated a net inflow of 0.38 Sv by analyzing the numerical model result of Hogan and Hurlburt (2000). Reliable flux estimates of the DW through the UIG, however, have not been available because of the lack of appropriate data. This paper presents results from the deployment of a current meter array from November 2002 through April 2004 whose central goal is to quantify the mean and temporal variability of the transport of the DW through the UIG.