Hydrography along the POSEIDON tracks in 2006~2009

Abstract

Water masses were analyzed by using CTD data surveyed in POSEIDON project during 4 years from 2006 to 2009. Total number of CTD stations was 115 and the numbers of station were 32, 24, 39 and 20 with years. Observation area was from the south sea of Korea to the tropical west Pacific, 33~11°N in latitude, 125~135°E in longitude. Observed water masses were the tropical surface which has high temperature (>28℃) and moderate salinity (~34 psu), the North Pacific Subtropical Water (T~25℃. S>35 psu), the North Pacific Intermediate Water (NPIW) which was characterized by a salinity minimum layer less than 34.5 psu below thermocline between 26 and 27.5 sigma-theta in potential density, the deep and bottom waters, and the continental shelf water of East China Sea which has low salinity less than 33 psu. The NPIW was divided by three groups with latitude. The first group appeared from south of Kuroshio to 19°N, the second one appeared 19~13°N, and the last one appeared south of 13°N. Salinity of the salinity minimum was increased with decreasing latitude. This classification of the NPIW was related to the circulation of the North Pacific.