Recent Trends in Oceanic Conditions in the Western Part of East/Japan Sea: An Analysis of Climate Regime Shift That Occurred after the Late 1990s

The western part of East/Japan Sea (WES) is an important area for understanding climate change processes and interactions between atmospheric and oceanic conditions. We analyzed the trends in recent oceanic conditions in the WES after the recent climate regime shift (CRS) that occurred in the late 1990s in the North Pacific. We explored the most important climate factors that affect oceanic conditions and determined their responses to changes in climate change. In the CRS that occurred in the late 1980s, changes in oceanic conditions in the WES were influenced by intensity changes in climate factors, and, in the late 1990s, it was by spatial changes in climate factors. The latitudinal shift of the Aleutian low (AL) pressure influences recent changes in oceanic and atmospheric conditions in the WES. The intensity of the Kuroshio Current and the sea level pressure in the Kuroshio extension region associated with the latitudinal shift of the AL pressure affects the volume of transport of the warm and saline water mass that flows into the WES and its atmospheric conditions. In addition, the fluctuations in the oceanic conditions of the WES affect various regions and depth layers differently, and these variations are evident even within the WES.

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Synchrony in the abundance trend of spear squid Loligo bleekeri in the Japan Sea and the Pacific Ocean with special reference to the latitudinal differences in response to the climate regime shift

ICES Journal of Marine Science ◽

10.1093/icesjms/fst015 ◽

2013 ◽

Vol 70 (5) ◽

pp. 968-979 ◽

Cited By ~ 14

Author(s):

Yongjun Tian ◽

Kazuya Nashida ◽

Hideo Sakaji

Keyword(s):

Pacific Ocean ◽

Environmental Factors ◽

Regime Shift ◽

Japan Sea ◽

Climate Regime ◽

Climate Regime Shift ◽

The Pacific ◽

The Japan Sea ◽

Abundance Trends ◽

The Pacific Ocean

Abstract Tian, Y., Nashida, K., and Sakaji, H. 2013. Synchrony in the abundance trend of spear squid Loligo bleekeri in the Japan Sea and the Pacific Ocean with special reference to the latitudinal differences in response to the climate regime shift. – ICES Journal of Marine Science, 70: 968–979. Spear squid Loligo bleekeri is widely distributed in the Japanese coastal waters. The fisheries depend largely on four stocks: the southern and northern stocks both in the Japan Sea and the coastal regions of the Pacific. The catch per unit effort (cpue) for the northern stock in the Japan Sea decreased substantially during the 1980s but increased during the 1990s, while the abundance index for the southern stock showed the opposite trend. The cpue for the southern and northern stocks in the Pacific coast showed a similar pattern to that in the Japan Sea. The synchrony in the abundance trends between the Japan Sea and the Pacific Ocean, and latitudinal differences between the northern and southern stocks indicate the impact of the climate regime shift. Generalized additive model analysis identified significant effects of environmental factors. Increased water temperature had a positive effect on the northern stock but a negative effect on the southern stock in the Japan Sea and the Pacific, whereas El Niño–southern oscillation events and the Asian monsoon had additional significant effects on the Pacific stocks. These results suggest that the abundance trends of spear squid were largely forced by environmental factors with latitudinal differences in the response to the climate regime shift.

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Response of the Kuroshio Extension to Rossby Waves Associated with the 1970s Climate Regime Shift in a High-Resolution Ocean Model*

Journal of Climate ◽

10.1175/jcli3449.1 ◽

2005 ◽

Vol 18 (15) ◽

pp. 2979-2995 ◽

Cited By ~ 52

Author(s):

Bunmei Taguchi ◽

Shang-Ping Xie ◽

Humio Mitsudera ◽

Atsushi Kubokawa

Keyword(s):

Boundary Layer ◽

High Resolution ◽

Regime Shift ◽

Rossby Waves ◽

Kuroshio Extension ◽

Ocean Model ◽

Western Boundary ◽

Climate Regime ◽

Climate Regime Shift ◽

The Kuroshio

Abstract The response of the Kuroshio Extension (KE) to large-scale Rossby waves remotely excited by wind stress changes associated with the 1970s climate regime shift is studied using a high-resolution regional ocean model. Two ensemble simulations are conducted: The control run uses monthly climatological forcing while, in the second ensemble, anomalous forcing is imposed at the model eastern boundary around 165°E derived from a hindcast of decadal changes in subsurface temperature and salinity using a coarser-resolution model of the Pacific basin. Near the KE, ocean adjustment deviates strongly from the linear Rossby wave dynamics. Most notably, the eastward acceleration of the KE is much narrower in meridional extent than that associated with the incoming Rossby waves imposed on the eastern boundary. This KE acceleration is associated with an enhanced potential vorticity (PV) gradient across the front that is consistent with the inertial western boundary layer theory: the arrival of the Rossby waves at the western boundary causes the eastward current to accelerate, leading to enhanced advection of low (high) PV water of subtropical (subarctic) origin along the western boundary layer. The meridional dipole of PV anomalies results in a pair of anomalous recirculations with a narrow eastward jet in between. A three-layer quasigeostrophic model is used to demonstrate this inertial adjustment mechanism. Finally, transient eddy activity increases significantly and the eddy momentum transport acts to strengthen the mean flow response. The result that ocean physical response to broad-scale atmospheric forcing is large near the KE front has important implications for fisheries research.

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