Late-1980s Regime Shift in the Formation of the North Pacific Subtropical Mode Water SCIE SCOPUS

Cited 4 time in WEB OF SCIENCE Cited 3 time in Scopus
Title
Late-1980s Regime Shift in the Formation of the North Pacific Subtropical Mode Water
Author(s)
Kim, Sang-Yeob; Pak, Gyundo; Lee, Ho Jin; Kwon, Young-Oh; Kim, Young Ho
KIOST Author(s)
Pak, Gyundo(박균도)
Publication Year
2020-02
Abstract
The formation mechanism as well as its temporal change of the North Pacific subtropical mode water (NPSTMW) is investigated using a 50-year (1960-2009) ocean general circulation model hindcast. The volume budget analysis suggests that the formation of the NPSTMW is mainly controlled by the air-sea interaction and ocean dynamics, but there is a regime shift of the relative importance between the two around late-1980s. While the local air-sea interaction process is a main driver of the NPSTMW formation prior to late-1980s, ocean dynamics including the vertical entrainment become dominant since then. The NPSTMW formation is affected by the North Pacific Oscillation simultaneously in the early period, but with a few years lag in the later period. The interdecadal change of the driving mechanism of the interannual variability of the NPSTMW is probably due to the stronger (weaker) influence of local atmospheric forcing in the western North Pacific and unfavorable (favorable) wind stress curl condition for the remote oceanic forcing from the central North Pacific during the former (later) period. This regime shift may be related to the change of centers of the actions of the wind stress curl since the late-1980s. Plain Language Summary Using a three-dimensional ocean model, we conduct a numerical simulation for 1960-2009. The ocean model reproduces well the feature of the North Pacific subtropical mode water (NPSTMW), which is characterized by a thick subsurface layer of the relatively uniform temperature and potential density, to the east and south of Japan. During cooling seasons (from December to following March), the NPSTMW is formed by the atmospheric cooling and the oceanic processes, such as the deepening of the mixed layer depth and advective flux. Our study found that the relative contributions from the two factors differ in two different epochs, before and after late-1980s. Before late-1980s, the atmospheric cooling mainly controls the NPSTMW formation, while the oceanic processes driven by remote forcing significantly contribute the NPSTMW formation after late-1980s. The variability of the NPSTMW formation is related to the basin-scale climate variability, particularly the North Pacific Oscillation.
ISSN
2169-9275
URI
https://sciwatch.kiost.ac.kr/handle/2020.kiost/38744
DOI
10.1029/2019JC015700
Bibliographic Citation
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, v.125, no.2, 2020
Publisher
AMER GEOPHYSICAL UNION
Subject
MIXED-LAYER CLIMATOLOGY; DECADAL VARIABILITY; ATMOSPHERIC CIRCULATION; REPRESENTATION; REEMERGENCE; TEMPERATURE; TOPOGRAPHY; AREA; GYRE
Keywords
Kuroshio Extension; North Pacific Oscillation; North Pacific subtropical mode water; ocean general circulation model; regime shift; volume budget
Type
Article
Language
English
Document Type
Article
Publisher
AMER GEOPHYSICAL UNION
Related Researcher
Research Interests

Ocean modeling,Data assimilation,Air-sea interaction,해양모델링,자료동화,해양대기 상호작용

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