A5002096795- Oceanographic and Atmospheric Processes
- Marine and coastal ecosystems
- Climate variability and models
- Geology and Paleoclimatology Research
- Arctic and Antarctic ice dynamics
- Radioactive contamination and transfer
- Methane Hydrates and Related Phenomena
- Ocean Acidification Effects and Responses
- Tropical and Extratropical Cyclones Research
- Radioactive element chemistry and processing
- Marine and fisheries research
- Ocean Waves and Remote Sensing
- Isotope Analysis in Ecology
- Geological and Geophysical Studies
- Atmospheric and Environmental Gas Dynamics
- Marine Biology and Ecology Research
- Radiation Detection and Scintillator Technologies
- Geological Studies and Exploration
- Underwater Acoustics Research
- Radioactivity and Radon Measurements
- Meteorological Phenomena and Simulations
- Arctic and Russian Policy Studies
- Marine and environmental studies
- earthquake and tectonic studies
- Water Quality Monitoring Technologies
The University of Tokyo
2015-2024
Sphere Institute
2013-2023
Tokyo University of Science
2019
Japan Agency for Marine-Earth Science and Technology
2003-2012
Institute for Global Environmental Strategies
2003-2004
In the past two decades, Argo Program has collected, processed and distributed over million vertical profiles of temperature salinity from upper kilometers global ocean. A similar number subsurface velocity observations near 1000 dbar have also been collected. This paper recounts history Program, its aspiration arising out World Ocean Circulation Experiment, to development implementation instrumentation telecommunication systems, various technical problems encountered. We describe data...
Abstract The Kuroshio south of Japan is known to vacillate between a straight and large meander (LM) path. Since 1950, eight LM events have been observed with different durations. most recent/on‐going started in August 2017 has become the longest event record. By analyzing eddy‐resolving sea surface height data by adopting wind‐forced linear vorticity model, we demonstrate that on‐going maintained an exceptionally stable dynamic state Extension (KE) forced wind stresses across Pacific basin....
Abstract Formation and subduction of the North Pacific Tropical Water (NPTW), its interannual variability, associated mechanisms were investigated by using gridded Argo-profiling float data various surface flux in 2003–11. The NPTW has two formation sites center subtropical gyre, corresponding to regional sea salinity maxima. Mixed layer variations these found be significantly different. While seasonal variation was prominent eastern site, dominant western site. mixed site controlled mainly...
The 137°E repeat hydrographic section of the Japan Meteorological Agency across western North Pacific was initiated in 1967 as part Cooperative Study Kuroshio and Adjacent Regions has been continued biannually winter summer. publicly available data from have widely used to reveal seasonal decadal variations long-term changes currents water masses, biogeochemical biological properties, marine pollutants relation climate variability such El Niño-Southern Oscillation Decadal Oscillation. In...
Surface flow jets and associated sea surface temperature (SST) distribution are investigated in the northwestern North Pacific, using satellite‐derived currents SST data that can resolve fine spatial scale structure. The combined use of these reveals warm tongue phenomena driven by geostrophic jets, which extend northeastward Kuroshio‐Oyashio transition area. They roughly coincide with Subarctic Front (SAF) defined as 4°C isotherm at 100 m depth. appear throughout year seasonal cycles, do...
Abstract Temperature and salinity data from Argo profiling floats in the North Pacific during 2003–08 have been analyzed to study structure of winter mixed layer north Kuroshio Extension subsurface potential vorticity distribution subtropical gyre relation formation subduction central mode water (CMW). In late winter, two zonally elongated bands deep extend at 33°–39° 39°–43°N, east coast Japan 160°W. These correspond region lighter variety CMW (L-CMW) that denser (D-CMW) recently identified...
Abstract Half‐century‐long observations at the 137°E repeat hydrographic section across western North Pacific have been analyzed to demonstrate remotely forced decadal physical and biogeochemical variability of Subtropical Mode Water (STMW) over last 40 years. During unstable periods Kuroshio Extension (KE) that lagged warm phase Decadal Oscillation by 3–4 years, high regional eddy activity reduced formation rate salinity STMW in its main region south KE. At Japan, decreasing southwestward...
Abstract Decadal modulations of the Kuroshio Extension (KE) system between a stable and an unstable dynamic state in western North Pacific have prevailed past three decades. This dominance decadal variations is controlled by negative feedback loop involving wind-forced KE variability its onto overlying extratropical storm tracks basin-scale surface wind field. The were disrupted August 2017 due to development large meander south Japan. By forcing inflow paths northward avoiding overriding...
Abstract Hydrographic data obtained by high-resolution shipboard observations and Argo profiling floats have been analyzed to study the mesoscale structure circulation of North Pacific Subtropical Mode Water (STMW). The float show that in late winter 2008, STMW having a temperature approximately 18.8°, 17.7°, 16.6°C formed west 140°E, at 140°–150°E, east 150°E, respectively, recirculation gyre south Kuroshio Extension. After spring, newly gradually shift southward, decreasing thickness....
Abstract Airborne bacteria have been shown to act as condensation and ice nuclei in mixed‐phase clouds are consequently hypothesized significant effects on atmospheric processes even the global climate. However, few data available regarding their concentration variation air over open ocean. Aerosol samples were collected during three cruises early summers of 2013, 2014, 2016 Kuroshio Extension region northwest Pacific Ocean. The concentrations viable nonviable bacterial cells marine surface...
In 2014, we measured activity concentration of radiocesium in the western North Pacific Ocean. north Kuroshio Front high Fukushima-derived surface mixed layer 2012 had been transported eastward by 2014. south front found a subsurface maximum 200-600 m depth, which was similar to that observed 2012. The spread southward from 18°N 15°N between and suggests spreading into whole subtropical area 2014 due formation subduction mode water.
Abstract A repeat hydrographic section along 165°E was analyzed to verify a westward extension of the formation region North Pacific Ocean Central Mode Water (CMW) suggested by previous synoptic observations, and investigate relation between thermohaline fronts. The CMW extends at least as far west 155°E, much farther than recognized in study based on climatology. It is located two interfrontal regions Kuroshio Extension front Bifurcation (KBF), KBF subarctic front, where types CMW—namely,...
The 137°E repeat hydrographic section for 50 winters during 1967–2016 has been analyzed to examine interannual interdecadal variations and long-term changes of salinity temperature in the surface intermediate layers western North Pacific, with a particular focus on freshening subtropical gyre. Rapid both isobars isopycnals began mid-1990s persisted last 20 years upper main thermocline/halocline In addition, significant decadal variability existed mode water (STMW), as previously reported...
Abstract Decadal variability of the North Pacific subtropical mode water (STMW) and its influence on upper thermocline mixed layer are examined in a four-dimensional variational ocean re-analysis for Western over 30 years (FORA–WNP30). The STMW that forms south Kuroshio Extension becomes thick/cold thin/warm decadal timescales. These variations subducted advected to south, where thick (thin) causes heave up (down) above STMW, producing cold (warm) temperature anomalies at subsurface depths,...
Abstract Deep understanding of contemporary trends, variability and their controlling mechanisms ocean CO 2 chemistry are crucial in projecting the uptake acidification. In surface layers 137°E high‐frequency repeat hydrographic section Kuroshio recirculation (KR) region western North Pacific, salinity‐normalized total dissolved inorganic carbon (nDIC) summer exhibited a significant interannual to decadal ranging ±15 μmol kg −1 for years 1994–2018. It was positively correlated with thickness...