scholarly journals Recent Warming in the Western North Pacific in Relation to Rapid Changes in the Atmospheric Circulation of the Siberian High and Aleutian Low Systems*

2012 ◽  
Vol 25 (10) ◽  
pp. 3476-3493 ◽  
Author(s):  
Young-Hyang Park ◽  
Jong-Hwan Yoon ◽  
Yong-Hoon Youn ◽  
Frédéric Vivier
Keyword(s):  
Wind Stress ◽  
North Pacific ◽  
Western North Pacific ◽  
Rossby Waves ◽  
Delayed Response ◽  
Aleutian Low ◽  
Wind Stress Curl ◽  
Siberian High ◽  
Sst Variability ◽  
The Kuroshio

Abstract On the basis of a new East Asian winter monsoon (EAWM) index and by analyzing the relationship between sea surface temperature (SST) anomalies and different atmospheric and oceanic factors in winter, this study investigates the causes of the recent unusual warming in the western North Pacific Ocean. Analyses presented here emphasize the dual contribution from the atmosphere and ocean to the local SST variability, with the relative importance of each contributor varying with the period and place. During the period 1970–89, the EAWM, controlled mostly by the Siberian high, is predominantly responsible for the SST variability in most of the western North Pacific, whereas in the period 1990–2005 ocean dynamics become increasingly important in most places or even dominant in the Kuroshio–Oyasio Extension (KOE) region. The delayed response of the KOE SST to basinwide wind stress curl forcing via Rossby waves is epoch dependent and is significant at lags of 1, 3, and 4 yr before 1990 but only at 1 yr afterward. This epoch dependency of the impact of Rossby waves is related to the different locations of the centers of action of wind stress curl in the midlatitude North Pacific between the two epochs. In addition, mean advection of the EAWM-driven anomalous SST from the southern East China Sea, which can be transported into the KOE region in about a year by the Kuroshio, likely affects the KOE SST lagged by 1 yr. The strongest positive SST trend observed in the western North Pacific results from the combined effects of the abrupt weakening of the EAWM due to the unprecedented decline of the Siberian high and the increasing role of the ocean. The latter is best evidenced by the 1-yr delayed response of the western North Pacific via the gyre circulation adjustment to the basinwide decadal-scale wind stress curl change associated with the northward shift of the strengthened Aleutian low.

scholarly journals Phase Synchronisation in the Kuroshio Current System

2019 ◽  
Author(s):  
Ann Kristin Klose ◽  
René M. van Westen ◽  
Henk A. Dijkstra
Keyword(s):  
Wind Stress ◽  
North Pacific ◽  
Time Scale ◽  
Rossby Waves ◽  
Model Simulation ◽  
Current System ◽  
Global Climate Model ◽  
Kuroshio Current ◽  
Study Phase ◽  
The Kuroshio

Abstract. The Kuroshio Current System in the North Pacific displays path transitions on a decadal time scale. It is known that both internal variability involving barotropic and baroclinic instabilities and remote Rossby waves induced by North Pacific wind-stress anomalies are involved in these path transitions. However, the precise coupling of both processes and its consequences for the dominant decadal transition time scale are still under discussion. Here, we analyse the output of a multi-centennial long high-resolution global climate model simulation and study phase synchronisation between Pacific zonal wind-stress anomalies and Kuroshio Current System path variability. We apply the Hilbert transform technique to determine the phase and find epochs where such phase synchronisation appears. The physics of this synchronisation is shown to occur through the effect of the vertical motion of isopycnals, as induced by the propagating Rossby waves, on the instabilities of the Kuroshio Current System.

scholarly journals Interannual to Decadal Variability of the Upper-Ocean Heat Content in the Western North Pacific and Its Relationship to Oceanic and Atmospheric Variability

2018 ◽  
Vol 31 (13) ◽  
pp. 5107-5125 ◽  
Author(s):  
Hanna Na ◽  
Kwang-Yul Kim ◽  
Shoshiro Minobe ◽  
Yoshi N. Sasaki
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Large Scale ◽  
Decadal Variability ◽  
Kuroshio Extension ◽  
Heat Content ◽  
Western Boundary ◽  
Delayed Response ◽  
Atmospheric Variability ◽  
Wind Stress Curl

Three-dimensional oceanic thermal structures and variability in the western North Pacific (NP) are examined on the interannual to decadal time scales and their relationship to oceanic and atmospheric variability is discussed by analyzing observation and reanalysis data for 45 years (1964–2008), which is much longer than the satellite-altimetry period. It is shown that the meridional shift of the Kuroshio Extension (KE) and subarctic frontal zone (SAFZ) is associated with the overall cooling/warming over the KE and SAFZ region (KE–SAFZ mode). It appears, however, that changes in KE strength induce different signs of thermal anomalies to the south and north of the KE, not extended to the SAFZ (KE mode), possibly contributing to noncoherent variability between the KE and SAFZ. Thus, the KE and SAFZ are dependent on each other in the context of the KE–SAFZ mode, while the KE is independent of the SAFZ in terms of the KE mode. This intricate relationship is associated with different linkages to atmospheric variability; the KE–SAFZ mode exhibits a relatively fast response to the large-scale wind stress curl forcing in the NP, whereas the KE mode is related to a delayed response to the atmospheric forcing via jet-trapped baroclinic Rossby wave propagation. It is suggested that further knowledge of the underlying mechanisms of the two modes would contribute to understanding ocean–atmosphere feedback as well as potential predictability over the western boundary current region in the NP.

scholarly journals Phase synchronisation in the Kuroshio Current System

Ocean Science ◽  
2020 ◽  
Vol 16 (2) ◽  
pp. 435-449
Author(s):  
Ann Kristin Klose ◽  
René M. van Westen ◽  
Henk A. Dijkstra
Keyword(s):  
Wind Stress ◽  
North Pacific ◽  
Rossby Waves ◽  
Climate Model ◽  
Model Simulation ◽  
Current System ◽  
Global Climate Model ◽  
Kuroshio Current ◽  
Study Phase ◽  
The Kuroshio

Abstract. The Kuroshio Current System in the North Pacific displays path transitions on a decadal timescale. It is known that both internal variability involving barotropic and baroclinic instabilities and remote Rossby waves induced by North Pacific wind stress anomalies are involved in these path transitions. However, the precise coupling of both processes and its consequences for the dominant decadal transition timescale are still under discussion. Here, we analyse the output of a multi-centennial high-resolution global climate model simulation and study phase synchronisation between Pacific zonal wind stress anomalies and Kuroshio Current System path variability. We apply the Hilbert transform technique to determine the phase and find epochs where such phase synchronisation appears. The physics of this synchronisation are shown to occur through the effect of the vertical motion of isopycnals, as induced by the propagating Rossby waves, on the instabilities of the Kuroshio Current System.

scholarly journals North Pacific Decadal Variability in the Community Climate System Model Version 2

2007 ◽  
Vol 20 (11) ◽  
pp. 2416-2433 ◽  
Author(s):  
Young-Oh Kwon ◽  
Clara Deser
Keyword(s):  
Heat Flux ◽  
Wind Stress ◽  
North Pacific ◽  
Decadal Variability ◽  
Kuroshio Extension ◽  
Flux Divergence ◽  
Wind Stress Curl ◽  
Climate System Model ◽  
Spectral Peaks ◽  
The Kuroshio

Abstract North Pacific decadal oceanic and atmospheric variability is examined from a 650-yr control integration of the Community Climate System Model version 2. The dominant pattern of winter sea surface temperature (SST) variability is similar to the observed “Pacific decadal oscillation,” with maximum amplitude along the Kuroshio Extension. SST anomalies in this region exhibit significant spectral peaks at approximately 16 and 40 yr. Lateral geostrophic heat flux divergence, caused by a meridional shift of the Kuroshio Extension forced by basin-scale wind stress curl anomalies 3–5 yr earlier, is responsible for the decadal SST variability; local surface heat flux and Ekman heat flux divergence act as a damping and positive feedback, respectively. A simple linear Rossby wave model is invoked to explicitly demonstrate the link between the wind stress curl forcing and decadal variability in the Kuroshio Extension. The Rossby wave model not only successfully reproduces the two decadal spectral peaks, but also illustrates that only the low-frequency (>10-yr period) portion of the approximately white noise wind stress curl forcing is relevant. This model also demonstrates that the weak and insignificant decadal spectral peaks in the wind stress curl forcing are necessary for producing the corresponding strong and significant oceanic peaks in the Kuroshio Extension. The wind stress curl response to decadal SST anomalies in the Kuroshio Extension is similar in structure but opposite in sign and somewhat weaker than the wind stress curl forcing pattern. These results suggest that the simulated North Pacific decadal variability owes its existence to two-way ocean–atmosphere coupling.

Generation of Annual Rossby Waves in the North Pacific by the Wind Stress Curl

1986 ◽  
Vol 16 (7) ◽  
pp. 1179-1189 ◽  
Author(s):  
Patrick F. Cummins ◽  
Lawrence A. Mysak ◽  
Kevin Hamilton
Keyword(s):  
Wind Stress ◽  
North Pacific ◽  
Rossby Waves ◽  
Wind Stress Curl ◽  
The North ◽  
The North Pacific

Frequency-Wavenumber Spectra of Sea Surface Temperature and Wind-Stress Curl in the Eastern North Pacific

1981 ◽  
Vol 11 (8) ◽  
pp. 1059-1077 ◽  
Author(s):  
Artemio Gallegos-Garcia ◽  
William J. Emery ◽  
Robert O. Reid ◽  
Lorenz Magaard
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Wind Stress ◽  
North Pacific ◽  
Sea Surface ◽  
Wind Stress Curl

scholarly journals An Examination of the Thermodynamic Impacts of Western North Pacific Tropical Cyclones on Their Tropical Tropospheric Environment

2015 ◽  
Vol 28 (19) ◽  
pp. 7529-7560 ◽  
Author(s):  
Benjamin A. Schenkel ◽  
Robert E. Hart
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Rossby Waves ◽  
Budget Analysis ◽  
Surface Latent Heat Flux ◽  
Static Energy ◽  
Thermodynamic Anomalies ◽  
Meridional Advection ◽  
Gas Effect ◽  
Sst Anomalies

Abstract The present study examines the tropospheric thermodynamic anomalies induced by western North Pacific tropical cyclone (TC) passage using storm-relative composites. Negative moist static energy (MSE) anomalies containing embedded westward-propagating anomalies generally occur only following larger TCs for two months following TC passage in a region extending from the domain center to ~3000 km to its west. Larger TCs force negative MSE anomalies likely because of feedbacks from stronger, broader TC-induced negative sea surface temperature (SST) anomalies and the excitation of TC-induced Rossby waves to the southeast of the TC. The negative MSE anomalies are composed of lower- and midtropospheric negative latent energy anomalies with smaller contributions from boundary layer and upper-tropospheric negative sensible heat anomalies. The lower- and midtropospheric negative MSE anomalies are forced by the TC, whereas the upper-tropospheric negative MSE anomalies are forced by the Madden–Julian oscillation. Vertically integrated MSE budgets at the domain center reveal negative MSE tendencies that are primarily forced by surface latent heat flux anomalies resulting from the TC-induced negative SST anomalies. Smaller negative MSE tendencies are due to 1) zonal and meridional advection of MSE anomalies by the Rossby waves and 2) enhanced top-of-the-atmosphere longwave radiative flux anomalies potentially associated with a reduction in the greenhouse gas effect of water vapor. The budget analysis in the west region is generally similar except that all terms are comparable in magnitude and relatively weaker. These results conservatively suggest that larger TCs can anomalously cool and dry their synoptic-scale environment for ~40 days following TC passage.

Geographical shift of zooplankton communities and decadal dynamics of the Kuroshio-Oyashio currents in the western North Pacific

2009 ◽  
Vol 15 (7) ◽  
pp. 1846-1858 ◽  
Author(s):  
SANAE CHIBA ◽  
HIROYA SUGISAKI ◽  
MASAMI NONAKA ◽  
TOSHIRO SAINO
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Zooplankton Communities ◽  
The Kuroshio
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