TOCS and TRITON Buoy Project
Yoshifumi Kuroda, Kentaro Ando, Yuji Kashino, Hiroshi Matsuura, Norifumi Ushijima (JAMSTEC) and Kei Muneyama (MWJ)
1. Purpose of the project
In the global oceans, the western tropical Pacific shows the warmest sea surface temperature around 29-30 degree-C with the widest size. This warmest area is called 'warm water pool'. As atmospheric convection is very sensitive to the temperature variation at such high temperature range (around 28 degree-C) , small change of surface temperature in the warm water pool is one of factors to change atmospheric circulation pattern over the tropical Pacific ocean. Due to the El Nino phenomenon, the highest sea surface area expands eastward, and the warm water pool seems to move east. Such changes of sea surface temperature in the tropical Pacific cause tropical climate change and strongly affects to cause global climate change in interannual time scale.
The purpose of the TOCS (Tropical Ocean Climate Study) project is to clarify the role of warm water pool in the western tropical Pacific to the global climate change in the seasonal to interannual time scales. As the first step, we have been investigated the ocean circulation variability in the western tropical Pacific Ocean. In this report, we will review our activity in the past and our future plan.
2. Reviews of the project
2-1. Review of ocean current variability in the western Pacific
We have been measuring the surface current variability in the western Pacific by using the upward-looking ADCP moorings. The sites we deployed are 0N138E, 0N42E, 0N147E, 0N156E and 0N165E along the equator, and 2S142E and 2.5S142E near the New Guinea Coast. From these data, the surface New Guinea Coastal Current upper 100m is closely correlated with local monsoonal winds and change the current direction seasonally. The westward New Guinea Coastal Undercurrent of which core is at about 200m is relatively steady, although it shows seasonal variations as it is intensified in boreal summer and weaken in boreal winter. In these currents intra-seasonal variations at the period of 20-30 days are dominant (Kuroda (1999); contact to kuroday@jamstec.go.jp).
