IUGG 2003 Abstract

P02 Marginal and Semi-Enclosed Seas and their Exchange with the Open Ocean  Monday, June 30 AM Location: Site C, Room 25 Presiding Chair:J. Johnson

TIME [ 1000 ] [ P02/30A/C25-005 ]

OBSERVATIONS OF THE JAPAN/EAST SEA BOTTOM WATER VENTILATION

Vyacheslav B. LOBANOV(V.I. Ilichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences)

Vladimir I. PONOMAREV(V.I. Ilichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences) Anatoly N. SALYUK ( V.I. Ilichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences ) Lynne D. TALLEY ( Scripps Institution of Oceanography, University of California, San Diego ) Pavel Y. TISHCHENKO ( V.I. Ilichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences ) Kuh KIM ( OCEAN Lab., School of Earth & Environmental Sciences, Seoul National University ) Kyung-Ryul KIM ( OCEAN Lab., School of Earth & Environmental Sciences, Seoul National University ) Dong-Jin KANG ( OCEAN Lab., School of Earth & Environmental Sciences, Seoul National University ) Guebuem KIM ( OCEAN Lab., School of Earth & Environmental Sciences, Seoul National University )

A series of cruises with CTD and chemical observations implemented during 1999-2003 has provided an evidence of deep convection and water mass formation processes in the northwestern Japan/East Sea. While an open sea convection was observed to penetrate down to 1100-1900 m in severe winters and ventilate high salinity intermediate layer, a renewal of bottom water was caused by slope convection at the area around Peter the Great Bay. As a result of extremely cold winter of 2000-2001 large amount of new bottom water (NBW) was observed in late February at a few stations located close to continental slope. It was a layer of 200-800 m thick overlaying the bottom (2700-3200 m) with water of high oxygen content (235-245 um/kg) and negative potential temperature anomaly of 0.02-0.18 C. The following cruises in April and May-June have revealed distribution of NBW by bottom currents over the whole western part of the deep Japan Basin down south to 40-15 N. An estimation of NBW layer thickness gives that around 14% of bottom water was renewed and its oxygen content had increased by 0.8%. One year later, in April 2002 the NBW was still observed at 18 stations in the western Japan Basin and found to be advected further southward down to 38 N toward Ulleung Basin. In spite of much weaker T, S and chemical signals it was still recognizable in a 100-400 m layer over the bottom. Prominent spatial variation of NBW characteristics suggests different locations or time of its formation. Another direct observations of small injections of shelf water down into the deep basin in 1999 and 2000 suggest that week ventilation by slope convection process might took place in other years. However even an intense ventilation event of 2001 does not seem to be strong enough to create low temperature and high oxygen conditions of the Japan/East Sea interior observed in the middle of last century