2006년 여름에 하와이~서태평양 사이에서 관측된 해수물성과 해류 특성

Abstract

Hydrographic survey and current measurements were carried out by KORDI team during the Hawaii to western Pacific Cruise between August 25 and September 30, 2006. The total study area can be classified into three regions by the overall temperature-salinity characteristics: 1) central N. Pacific (CP) region from Hawaii to Micronesia, 2) island region near Chuuk, Micronesia (CM), and 3) northwestern Pacific (WP) region between 130oE and 135oE. Salinity maximum core is the highest (S~35.2) at the subsurface depths and the lowest (S~34.1) below the thermocline depths in CP. The range of salinity is reduced in the western Pacific; salinity maximum is up to 35.1 and the minimum is about 34.2 or higher, respectively. Near islands around Chuuk, Micronesia (CM), the upper maximum is even more reduced down to 34.8 and the lower minimum is about 34.5 and there is another salinity maximum core (S~34.65) invading into the middle of the broad depths of salinity minimum layer by the North Pacific Intermediate Water (NPIW). Consistent westward flows were measured in the upper layer by ADCP, which primarily represented the North Equatorial Currents (NEC) across the longitudes 135oE and 130oE, except near the northern tip from 18oN to 20oN at 130oE, where the currents flow in the opposite direction (eastward). The vertical structures of current profiles were also examined and compared one another, which were obtained by the lowered ADCP at the CTD stations along the cruise track in the study area. During the cruise, the SST positive anomalies at Nino 3.4 region were in a rising phase (beginning of El Nino), which had been persistently strengthening for the next winter (and still going on). The currents and hydrographic structure from the central to western Pacific regions are considered with respect to the ENSO phases in the North Pacific Ocean.