Evolution and decay of a warm-core ring within the western subarctic gyre of the North Pacific,as observed by profiling floats |
| |
| Authors: | Sachihiko Itoh Yugo Shimizu Shin-ichi Ito Ichiro Yasuda |
| |
| Institution: | (1) Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa Chiba, 277-8564, Japan;(2) Tohoku National Fisheries Research Institute, Fisheries Research Agency, 3-27-5 Shinhama-cho, Shiogama Miyagi, 985-0001, Japan |
| |
| Abstract: | This study investigated temporal variations in the vertical structure and water properties of a warm-core ring that migrated
into the western subarctic gyre of the North Pacific, based on analyses of temperature and salinity data derived from two
profiling floats, together with shipboard and satellite observation data. The floats were initially deployed into cold and
fresh Oyashio water in September 2003, and were entrained into a warm-core ring in October 2003, remaining within the ring
until detrainment in December 2004. Drastic cooling and freshening of the upper core water of the ring were observed during
the above entrainment of the floats with cold and fresh water into the ring, whereas moderate variations in structure and
water properties were observed during a quasi-isolated phase from November 2003 to November 2004 when the ring did not experience
major interactions with ambient hydrographic features. The upper part of the core water (upper core), with relatively warm/saline
water above 26.6 σ
θ
, was under the influence of the atmosphere in winter via the formation of a deep mixed layer exceeding 300 dB, and had a
prominent pycnostad below the seasonal pycnocline from spring to autumn. In contrast, the lower core, with relatively cold
and fresh water below 26.6 σ
θ
, was not ventilated throughout the observation period. Isopycnal surfaces showed a shoaling trend of about 50 dB/year during
the quasi-isolated phase, suggesting viscous decay over a timescale of several years. Markedly cold and thick water was also
frequently observed within the ring, indicating the intrusion of water from the Sea of Okhotsk. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
