Local Advective Mechanism for Interdecadal Variability in Circulations Driven by Constant Surface Heat Fluxes in Idealized Basins SCIE SCOPUS

Cited 1 time in WEB OF SCIENCE Cited 1 time in Scopus
Title
Local Advective Mechanism for Interdecadal Variability in Circulations Driven by Constant Surface Heat Fluxes in Idealized Basins
Author(s)
Park, Young-Gyu; Hwang, Jin Hwan
KIOST Author(s)
Park, Young Gyu(박영규)
Publication Year
2009-08
Abstract
Idealized numerical experiments with a depth level coordinate ocean circulation model (GFDL MOM3) have been conducted to investigate the structure of interdecadal variability from thermally driven circulations. The model oceans are driven by steady surface heat fluxes in the absence of surface wind stresses. Interdecadal variability is observed, with characteristics similar to those reported in many previous studies. To explain the nature of the variability we propose a new mechanism based on two local horizontal advective processes. This overcomes the limitations in previous theories based on the interplay between global properties such as zonal and meridional temperature gradients and overturning. One of the two advective processes is a zonal flow anomaly induced by a temperature anomaly along the northern wall through geostrophy southward of the temperature anomaly. A cold (warm) anomaly along the northern wall produces a positive (negative) zonal flow anomaly that induces a warm (cold) temperature anomaly by enhancing (weakening) warm advection from the western boundary along the path of the zonal flow anomaly. The temperature and flow anomalies are transported toward the eastern boundary by the mean eastward zonal flow. When the positive (negative) zonal flow anomaly that accompanies the warm (cold) temperature anomaly encounters the eastern wall, a downwelling (upwelling) anomaly is produced. To dissipate the vorticity due to this downwelling (upwelling) anomaly, a northward (southward) flow anomaly, which is another advective process governing the variability, is generated within a frictional boundary layer next to the eastern wall. The northward (southward) flow anomaly circulates cyclonically along the perimeter of the basin while enhancing (reducing) warm advection. So does the warm (cold) temperature anomaly carried to the eastern wall by the mean zonal flow while pushing the cold (warm) anomaly that produced the positive (negative) zonal flow anomaly westward and initiating the other half cycle of the variability. During the anomalous downwelling or upwelling, the available potential energy stored in the anomalous density field is released to maintain the variability. Thus, neither barotropic nor baroclinic instability supplies energy for the variability. The anomalous vertical velocity is stronger along the northern boundary and the northern part of the eastern boundary. A shallow continental slope added along those boundaries prohibits the anomalous vertical motion and weakens variability very effectively, while one along the western boundary does not.
ISSN
0916-8370
URI
https://sciwatch.kiost.ac.kr/handle/2020.kiost/4274
DOI
10.1007/s10872-009-0047-3
Bibliographic Citation
JOURNAL OF OCEANOGRAPHY, v.65, no.4, pp.549 - 566, 2009
Publisher
SPRINGER
Subject
DEPTH-COORDINATE MODEL; ISOPYCNIC-LAYER MODEL; NORTH-ATLANTIC OCEAN; THERMOHALINE CIRCULATION; PARAMETER SENSITIVITY; OSCILLATIONS; INSTABILITY; ATMOSPHERE
Keywords
Thermohaline variability; interdecadal variability; ocean modeling
Type
Article
Language
English
Document Type
Article
Publisher
SPRINGER
Related Researcher
Research Interests

ocean circulation,ocean mixing,marine debris,해양순환,해양혼합,해양부유물

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