SUBMESOSCALE ANOMALIES IN THE NORTH PACIFIC SUB-ARCTIC FRONT

Citation
N. Maximenko et T. Yamagata, SUBMESOSCALE ANOMALIES IN THE NORTH PACIFIC SUB-ARCTIC FRONT, J GEO RES-O, 100(C9), 1995, pp. 18459-18469
Citations number
32
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Oceanografhy
Journal title
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
ISSN journal
2169-9275 → ACNP
Volume
100
Issue
C9
Year of publication
1995
Pages
18459 - 18469
Database
ISI
SICI code
2169-9275(1995)100:C9<18459:SAITNP>2.0.ZU;2-A
Abstract
Data analysis of the experiment ''Megapolygon-87'', targeted at large- scale and mesoscale currents, revealed a submesoscale coherent eddy wi th a core of anomalously cold water south of the North Pacific Subarct ic Front (SF). TS characteristics of the core water are similar to the ones of the Subarctic water mass north of SF. The core occupies a dep th range from 950 through at least 1500 m and has an outer diameter of 40 km. The maximum value of thermal anomaly of -0.5 degrees C is loca ted at 1000 m depth. Anticyclonic orbital velocity reaches 30 cm/s at 10-km radius at the edge of the internal core, rotating nearly as a so lid body. The 7 cm/s translating eddy is governed by the larger-scale currents. Significant seawater density anomalies above the lens are ex plained by the interaction of the lens with a mean horizontal flow wit h strong vertical shear. The lens was probably formed either by upper layer cooling during the previous winter-spring season, able to genera te deep convection processes and move surface water to the middle and lower part of the main thermocline, or by instability of the countercu rrent existing below SF. No direct observations of those processes in the northwestern Pacific are available at present. Other similar subme soscale anomalies have been found in the area south of SF.