PICES Press, Vol. 6, No. 2, July 1998

CREAMS, PICES and the exploration of the Japan/East Sea The state of the eastern North Pacific from September 97 to February 98 The state of the western North Pacific in the second half of 1997 The status of the Bering Sea in the second half of 1997 Hyung Tack Huh Report on GOOS Living Marine Resource Panel Meeting Global connections: A report of the GLOBEC International Open Science Meeting Update on U.S. GLOBEC research projects and coordination activities in the Northeast Pacific Institutional framework for oceanographic research in Japan The Kuroshio Edge Exchange Processes (KEEP) Project Report on NPAFC Workshop on Climate Change and Salmon Production A new ocean time series station in the western subarctic Pacifi

PICES Press, Vol. 18, No. 2, Summer 2010

•The 2010 Inter-sessional Science Board Meeting: A Note from the Science Board Chairman (pp. 1-3) •2010 Symposium on “Effects of Climate Change on Fish and Fisheries” (pp. 4-11) •2009 Mechanism of North Pacific Low Frequency Variability Workshop (pp. 12-14) •The Fourth China-Japan-Korea GLOBEC/IMBER Symposium (pp. 15-17, 23) •2010 Sendai Ocean Acidification Workshop (pp. 18-19, 31) •2010 Sendai Coupled Climate-to-Fish-to-Fishers Models Workshop (pp. 20-21) •2010 Sendai Salmon Workshop on Climate Change (pp. 22-23) •2010 Sendai Zooplankton Workshop (pp. 24-25, 28) •2010 Sendai Workshop on “Networking across Global Marine Hotspots” (pp. 26-28) •The Ocean, Salmon, Ecology and Forecasting in 2010 (pp. 29, 44) •The State of the Northeast Pacific during the Winter of 2009/2010 (pp. 30-31) •The State of the Western North Pacific in the Second Half of 2009 (pp. 32-33) •The Bering Sea: Current Status and Recent Events (pp. 34-35, 39) •PICES Seafood Safety Project: Guatemala Training Program (pp. 36-39) •The Pacific Ocean Boundary Ecosystem and Climate Study (POBEX) (pp. 40-43) •PICES Calendar (p. 44

Mean transport and seasonal cycle of the Kuroshio east of Taiwan with comparison to the Florida Current

Moored observations of Kuroshio current structure and transport variability were made across the channel between northeast Taiwan and the Ryukyu Islands at 24 degreesN from September 19, 1994, to May 27, 1996. This was a cooperative, effort between the United States and Taiwan. The moored array was designated PCM-1, for the World Ocean Circulation Experiment (WOCE) transport resolving array. The dominant current and transport variability occurred on 100-day timescales and is shown by Zhang et al. [2001] to be caused by warm mesoscale eddys merging with the Kuroshio south of the array causing offshore meandering and flow splitting around the Ryukyu Islands. An annual transport cycle could not be resolved from our 20-month moored record because of abasing from the 100-day period events. Sea level difference data were used to extend the transport time series to 7 years giving a variation in the range of the annual transport cycle of 4-10 Sv, with a mean range closer to 4 Sv. The seasonal maximum of 24 Sv occurred in the summer and the seasonal minimum of 20 Sv occurred in the fall. A weaker secondary maximum also occurred in the winter. The cycle of Kuroshio transport appears to result from a combination of local along-channel wind forcing and Sverdrup forcing over the Philippine Sea. Our estimate of the mean transport of the Kuroshio at the entrance to the East China Sea from the moored array is 21.5 +/- 2.5 Sv. The mean transpacific balance of meridional flows forced by winds and thermohaline processes at this latitude requires an additional mean northward flow of 12 Sv with an annual cycle of +/-8 Sv along the eastern boundary of the Ryukyu Islands. The mean transport and annual cycle of the Kuroshio were found to be in reasonable agreement with basin-scale wind-forced models. Remarkable similarities are shown to exist between the mean western boundary currents and their seasonal cycles in the Atlantic (Florida Current and Antilles Current) and Pacific (Kuroshio and boundary current east of Ryukyu Island chain) at the same latitude. However, detailed comparison shows that the mean Kuroshio is weaker and more surface intensified than the mean Florida Current, while the Kuroshio-transport variability is significantly larger

Mean structure and variability of the Kuroshio from northeastern Taiwan to southwestern Japan

Author Posting. © The Oceanography Society, 2015. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 28, no. 4 (2015): 84-95, doi:10.5670/oceanog.2015.84.In the subtropical western North Pacific Ocean, the Kuroshio delivers heat, salt, and momentum poleward, much like its North Atlantic analog, the Gulf Stream. Though the Kuroshio generally flows along the western boundary from Taiwan to southeastern Japan as an “attached” current, the Kuroshio’s strength, vertical structure, and horizontal position undergo significant temporal and spatial variability along this entire route. Ubiquitous mesoscale eddies and complicated topography associated with a string of marginal seas combine to make the western North Pacific a region with complex circulation. Here, we synthesize results from the recent US Origins of the Kuroshio and Mindanao Currents and Taiwan Observations of Kuroshio Transport Variability observational programs with previous findings to build a comprehensive picture of the Kuroshio on its route from northeastern Taiwan to southeastern Japan, where the current finally transitions from a western boundary current into the Kuroshio Extension, a vigorously meandering free jet.ONR sponsored many of the field programs that are reported on in this study, including grant N00014-12- 1-0445 to MA and grant N00014-10-1-0468 to TBS. Additionally, MA received support from The Andrew W. Mellon Foundation Endowed Fund for Innovative Research. LC and the drifter work were supported by ONR grant N0001-10-1-0273 and NOAA grant NA10OAR4320156, “The Global Drifter Program.” SJ was sponsored by the Ministry of Science and Technology, ROC (Taiwan) grant NSC-101-2611-M- 002-018-MY3

On the dynamics of the seasonal variation in the South China Sea throughflow transport

Author Posting. © American Geophysical Union, 2013. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 118 (2013): 6854–6866, doi:10.1002/2013JC009367.The Luzon Strait transport (LST) of water mass from the Pacific Ocean to the South China Sea (SCS) varies significantly with seasons. The mechanisms for this large variability are still not well understood. The steady-state island rule, which is derived from a steady-state model, is not applicable to seasonal time scale variations in a large basin like the Pacific Ocean. In this paper, we will use a theoretical model that is based on the circulation integral around the Philippines. The model relates the LST variability to changes in the boundary currents along the east coast of the Philippines, including the North Equatorial Current (NEC) Bifurcation Latitude (NECBL), the transports of Kuroshio and Mindanao Currents (KC and MC), and to the local wind-stress forcing. Our result shows that a northward shift of the NECBL, a weakening of the KC or a strengthening of the MC would enhance the LST into the SCS. This relationship between the LST and the NEC-KC-MC is consistent with observations. The analytical result is tested by a set of idealized numerical simulations.This study has been supported by the National Science Foundation Grants (OCE 1028739, 0927017) (JY), and by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA11010103), the project of Global Change and Air-Sea interaction (GASI-03-01-01-02), the Natural Science Foundation of China (40930844, 41222037), the National Basic Research Program of China (2013CB956202), Ministry of Education’s 111 Project (B07036) of China, Yong Science Foundation of Shandong (JQ201111) and Public science and technology research funds projects of ocean (201205018) (XL and DW).2014-06-1

Eddy-Kuroshio interactions : local and remote effects

Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 122 (2017): 9744–9764, doi:10.1002/2017JC013476.Quasi-geostrophic mesoscale eddies regularly impinge on the Kuroshio in the western North Pacific, but the processes underlying the evolution of these eddy-Kuroshio interactions have not yet been thoroughly investigated in the literature. Here this interaction is examined with results from a semi-idealized three-dimensional numerical model and observations from four pressure-sensor equipped inverted echo sounders (PIESs) in a zonal section east of Taiwan and satellite altimeters. Both the observations and numerical simulations suggest that, during the interaction of a cyclonic eddy with the Kuroshio, the circular eddy is deformed into an elliptic shape with the major axis in the northwest-southeast direction, before being dissipated; the poleward velocity and associated Kuroshio transport decrease and the sea level and pycnocline slopes across the Kuroshio weaken. In contrast, for an anticyclonic eddy during the eddy-Kuroshio interaction, variations in the velocity, sea level, and isopycnal depth are reversed; the circular eddy is also deformed to an ellipse but with the major axis parallel to the Kuroshio. The model results also demonstrate that the velocity field is modified first and consequently the SSH and isopycnal depth evolve during the interaction. Furthermore, due to the combined effect of impingement latitude and realistic topography, some eddy-Kuroshio interactions east of Taiwan are found to have remote effects, both in the Luzon Strait and on the East China Sea shelf northeast of Taiwan.Ministry of Science and Technology Grant Numbers: MOST-101-2611-M-002-018-MY3, MOST 103-2611-M-002-011, MOST 105-2119-M-002-042; Office of Naval Research. Grant Numbers: N00014-15-12593, N00014-16-13069; MHC. Grant Number: MOST-101-2611-M-019-0022018-06-1

The Kuroshio and Luzon Undercurrent east of Luzon Island

Author Posting. © The Oceanography Society, 2015. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 28, no. 4 (2015): 54–63, doi:10.5670/oceanog.2015.81.Current structure, transport, and water mass properties of the northward-flowing Kuroshio and the southward-flowing Luzon Undercurrent (LU) were observed for nearly one year, June 8, 2012–June 4, 2013, across the Kuroshio path at 18.75°N. Observations were made from four platforms: an array of six subsurface ADCP moorings, two Seagliders, fivepressure inverted echo sounders (PIES), and five horizontal electric field (HEF) sensors, providing the most detailed time series of the Kuroshio and Luzon Undercurrent water properties to date. Ocean state estimates of the western boundary current system were performed using the MIT general circulation model—four-dimensional variational assimilation (MITgcm-4D-Var) system. Prominent Kuroshio features from observations are simulated well by the numerical model. Annual mean Kuroshio transport, averaged over all platforms, is ~16 Sv with a standard deviation ~4 Sv. Kuroshio and LU transports and water mass pathways east of Luzon are revealed by Seaglider measurements. In a layer above the salinity maximum associated with North Pacific Tropical Water (NPTW), Kuroshio transport is ~7 Sv and contains North Equatorial Current (NEC) and Western Philippine Sea (WPS) waters, with an insignificant amount of South China Sea water on the shallow western flank. In an intermediate layer containing the core of the NPTW, Kuroshio transport is ~10 Sv, consisting mostly of NEC water. In the lower layer of the Kuroshio, transport is ~1.5 Sv of mostly North Pacific Intermediate Water (NPIW) as a part of WPS waters. Annual mean Luzon Undercurrent southward transport integrated to 1,000 m depth is ~2.7 Sv with a standard deviation ~2 Sv, carrying solely WPS waters below the salinity minimum of the NPIW. The transport of the western boundary current integrated over the full ocean depth east of Luzon Island is ~14 ± 4.5 Sv. Sources of the water masses in the Kuroshio and Luzon Undercurrent are confirmed qualitatively by the numerical model.This work was supported by the US Office of Naval Research (N00014-10-1-0273 and N00014-15-1-2285 to BDC, N00014-10-1-0273 to GG, N00014-14-1-0065 to ALG, N00014-10-1-0468 to TBS, N0001-10-1-0273 to LRC, N00014-10-1-0308 to CML, N00014-10-1-0397 and N00014-10-1-0273 to BM, N00014-10-1-0397 to RCL, and N00014-10-1-0268 to SRJ) and the Taiwan Ministry of Science and Technology. Yang, Chang, and Mensah are supported by the Taiwan Ministry of Science and Technology

Impacts of wind forcing on sea level variations in the East China Sea: Local and remote effects

The regional sea level variation in the East China Sea (ECS) was influenced not only by local factors but also by remote wind from adjoining ocean with the oceanic connectivity influenced by upper-ocean circulation. The satellite altimeter observations showed that from 1993 to 2008, the inter-annual sea level variation in the ECS was negatively related to the strength of Kuroshio. To investigate the relative role of local and remote wind, two sensitive experiments were carried out using the POP model. Model experiments revealed that wind-induced redistributions of water played a significant role in the sea level variation of the ECS. The seasonal variations were induced by both local winds and remote Pacific wind stress with approximately equal contribution. However, on the inter-annual sea level variations, the remote wind forcing over the North Pacific could contribute substantially more than that of local wind which modulated sea level immediately. Remote wind influenced the China Sea in forms of changing of wind stress curl and ocean currents, which influenced the intensity of the Kuroshio, especially during El Nino episodes. (C) 2015 Elsevier B.V. All rights reserved

Oceanic Boundary Currents

Measurements of oceanic boundary currents for integral quantities such as heat and freshwater transports are very important for studying their long-term impacts on the global climate. There are a variety of boundary currents, including surface, intermediate and deep boundary currents on both the western and eastern sides of ocean basins. The dynamics and physics of these boundary currents are different, as are the ways of monitoring them. Here, we choose to explore the strategies adopted for observing four representative boundary current systems which have been the subject of detailed studies in recent years: the Kuroshio; the East Australian Current; the Indonesian Throughflow; and the low-latitude boundary current System of the Atlantic. The transport of the Kuroshio south of Japan has been monitored using satellite altimeter data in conjunction with an empirical relation between the transport and sea surface height difference across the stream. Monitoring the transport of the East Australian Current has been achieved by repeated high-resolution expendable bathythermograph (XBT) and/or conductivity-temperature-depth profiler transects maintained at several locations, supplemented with satellite altimeter data. Repeated XBT transects have also been used to monitor transport of the Indonesian Throughflow, in association with current meter and other instrumental estimations of transport through a few major throughflow straits. Finally, the complicated flow field of the low-latitude boundary current system of the Atlantic has been revealed using neutrally buoyant floats, moored current meters and hydrographic observations. The survey will be continued using further advanced observation technologies