Oceanographic Characteristics Along 137E in the Western Tropical Pacific - Comparison between two cruises of December 1992 and April 1994
Moon-Sik Suk, Gi-Hoon Hong, Soo Yong Nam, and Dong-Jin Kang
Korea Ocean Research and Development Institute
Seoul 425-600, Korea
An oceanographic survey section along 137E in the western tropical Pacific, that is located in the edge of the Warm-Pool, has been designed and conducted in December 1992 and April 1994. Since minor variability of the Warm-Pool, i.e., the changes in its position and the sea surface temperature, can influence the global climate system significantly, the section is important and essential for better understanding of global climate changes. Even though our country is located in the mid latitude, it is appropriate to view such anomalous variability in tropical regions as our own problem. Hence it is necessary to establish a foundation for tropical ocean research by obtaining available ocean data.
During the Onnuri cruise in December 1992, which was the first ocean-going cruise ever tried in Korea for purely scientific purposes, physical, chemical, and biological observations were made at every 1 degree in latitude between 1ON and 5N, and 30" between 5N and the Equator, along the 13'1E meridional line. At all stations, the CTD castings were made at all depths to the bottom, recording data during both downcast and upcast, and taking water samples during upcast. As well as, at the station at 2N, which is close to where our ATLAS buoy was moored, 24-hour continuous CTD measurements were made in the upper 500m. Another similar survey was conducted in April 1994, again.
The observed data are clearly distinct between tropical and extratropical regions. The Equatorial Undercurrent is detected in terms of hydrographic characteristics and currents observed by vessel-mounted acoustic doppler current profiler (ADCP). Dissolved oxygen and nutrients data are also useful to determine water mass characteristics. Using 24-hour observed data, we have remarked that the variation of the current in a day is quite significant and rapid. The variations of heat content and stability in the water column are also studied.
Internationally, the weight of open-ocean-related research in the field of oceanography is large. However, no systematic research has been conducted in Korea. Hence for successful conduction of open ocean research, it is necessary for experts in universities and other organizations nationwide to join the project. Since ocean cruise basically requires a great amount of fund for ship charges, it is advised to create an atmosphere so that as many experts from various organizations as possible can join the cruise.
