Title: Subtropical Mode Water Variability in a Climatologically Forced Model in the Northwestern Pacific Ocean

Abstract

A climatologically forced high-resolution model is used to examine variability of subtropical mode water (STMW) in the northwestern Pacific Ocean. Despite the use of annually repeating atmospheric forcing, significant interannual to decadal variability is evident in the volume, temperature, and age of STMW formed in the region. This long time-scale variability is intrinsic to the ocean. The formation and characteristics of STMW are comparable to those observed in nature. STMW is found to be cooler, denser, and shallower in the east than in the west, but time variations in these properties are generally correlated across the full water mass. Formation is found to occur south of the Kuroshio Extension, and after formation STMW is advected westward, as shown by the transport streamfunction. The ideal age and chlorofluorocarbon tracers are used to analyze the life cycle of STMW. Over the full model run, the average age of STMW is found to be 4.1 yr, but there is strong geographical variation in this, from an average age of 3.0 yr in the east to 4.9 yr in the west. This is further evidence that STMW is formed in the east and travels to the west. This is qualitatively confirmed through simulated dyemore » experiments known as transit-time distributions. Changes in STMW formation are correlated with a large meander in the path of the Kuroshio south of Japan. In the model, the large meander inhibits STMW formation just south of Japan, but the export of water with low potential vorticity leads to formation of STMW in the east and an overall increase in volume. This is correlated with an increase in the outcrop area of STMW. Mixed layer depth, on the other hand, is found to be uncorrelated with the volume of STMW.« less

Authors:

Douglass, Elizabeth M. ^[1]; Jayne, Steven R. ^[1]; Peacock, Synte ^[2]; Bryan, Frank O. ^[2]; Maltrud, Mathew E. ^[3]

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+ Show Author Affiliations

1. Woods Hole Oceanographic Inst., Woods Hole, MA
2. National Center for Atmospheric Research, Boulder, CO (United States)
3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Publication Date:

Wed Jan 25 00:00:00 EST 2012

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1564907

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Physical Oceanography

Additional Journal Information:

Journal Volume: 42; Journal Issue: 1; Journal ID: ISSN 0022-3670

Publisher:

American Meteorological Society

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; Oceanography