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1.
Following our previous study (Sugimoto and Hanawa, 2005b), we further investigate the reason why reemergence of winter sea
surface temperature anomalies does not occur in the North Pacific eastern subtropical mode water (NPESTMW) area, despite its
occurrence in the North Pacific subtropical mode water and North Pacific central mode water areas. We use vertical temperature
and salinity profiles of the World Ocean Circulation Experiment Hydrographic Program and Argo floats with high vertical and
temporal resolution, together with heat flux data through the sea surface. We point out first that one of the causes for non-occurrence
of reemergence is that the thickness of NPESTMW is very thin. In addition to this basic cause, two major reasons are found:
a vigorous mixing in the lower portion of NPESTMW and less heat input from the atmosphere in the warming season. Since, in
the lower portion of NPESTMW and deeper, the stratification is favorable for salt-finger type convection to occur compared
with the other mode water areas, vigorous mixing takes place. This is confirmed by both a large Turner Angle there and the
existence of staircase structures in vertical temperature and salinity profiles. From the viewpoint of heat input, the NPESTMW
area gradually gains heat in the warming season compared with other mode water areas. As a result, NPESTMW cannot be capped
so quickly by the shallow summer mixed layer, and water properties of NPESTMW are to be gradually modified, even in the upper
portion. 相似文献
2.
Makoto Yamano Masataka Kinoshita Shusaku Goto 《International Journal of Earth Sciences》2008,97(2):345-352
Thirty-three new measurements on the seaward slope and outer rise of the Japan Trench along a parallel of 38°45′N revealed
the existence of high heat flow anomalies on the subducting Pacific plate, where the seafloor age is about 135 m.y.. The most
prominent anomaly with the highest value of 114 mW/m2 is associated with a small mound on the outer rise, which was reported to be a kind of mud volcano. On the seaward slope
of the trench, heat flow is variable: high (70–90 mW/m2) at some locations and normal for the seafloor age (about 50 mW/m2) at others. The spatial variation of heat flow may be related to development of normal faults and horst/graben structures
due to bending of the Pacific plate before subduction, with fluid flow along the fault zones enhancing the vertical heat transfer.
Possible heat sources of the high heat flow anomalies are intra-plate volcanism in the last several million years like that
discovered recently on the Pacific plate east of the Japan Trench. 相似文献
3.
Jule Xiao Yoshio Inouchi Hisao Kumai Shusaku Yoshikawa Yoichi Kondo Tungsheng Liu Zhisheng An 《Quaternary Research》1997,47(3):277-283
The record of the biogenic silica flux (BSF, g cm−2(103yr)−1) in Lake Biwa reflects changes in diatom productivity in the lake and provides information regarding changes in paleoclimatic conditions. The BSF record of Lake Biwa demonstrates five periods over the past ca. 145,000 yr when the BSF values were significantly greater than 7.5 g cm−2(103yr)−1, and five intervals when they were lower. The data imply that paleoclimatic conditions were warmer and wetter from ca. 123,000 to 115,000, 103,000 to 95,000, 88,000 to 72,000, 57,000 to 32,000 yr B.P., and around ca. 6000 yr B.P. when the BSF values were greater, and relatively dry and cold from ca. 141,000 to 123,000 yr B.P. and during intervals between two of the five warm and wet episodes when the BSF values were lower. Time series of the BSF record can be correlated with the record of biogenic silica content in Lake Baikal and the marine oxygen isotope stages 1 through 6. Furthermore, the BSF values varied with much higher amplitude during the last interglaciation than during the last glaciation, probably implying that the diatom productivity in Lake Biwa was likewise more variable and had a larger range under interglacial conditions than under glacial conditions. 相似文献
4.
5.
Rachmat Fajar Lubis Makoto Yamano Robert Delinom Sudaryanto Martosuparno Yasuo Sakura Shusaku Goto Akinobu Miyakoshi Makoto Taniguchi 《Environmental Earth Sciences》2013,70(5):2033-2038
Urbanization has become one of the domain processes for city development in Indonesia. The results of the extremely high densities of fast growing population have led to negative subsurface environmental impact. Jakarta, as one of the rapidly developed and urbanized cities in Southeast Asia, has become one of the interesting urbanization city to analyze its effects. In Jakarta, the use of groundwater has greatly accelerated conforming to the rise in its population and the development of the industrial sector, which consume a relatively large amount of water. The increase of groundwater exploitation in Jakarta city has already caused a negative impact on these resources. Therefore, an assessment of groundwater trends in the urban area, including their hazard and risk management, is a necessary action. This paper describes the assessment of urban groundwater loading caused by human concentration in Jakarta city. Subsurface heat contamination under the condition of surface warming shows significant effects of urban groundwater loading during the past century in Jakarta city. 相似文献
6.
Shusaku Goto Masataka Kinoshita Kyohiko Mitsuzawa 《Marine Geophysical Researches》2003,24(3-4):345-357
A low-temperature diffuse flow site associated with abundant vent fauna was found by submersible observations on the southern East Pacific Rise at 17°25′ S in 1997. This site was characterized by thin sediment covered pillow and sheet lavas with collapsed pits up to ∼15 m in diameter. There were three warm water vents (temperature: 6.5 to 10.5 °C) within the site above which the vented fluids rise as plumes. To estimate heat flux of the warm water vents, a temperature logger array was deployed and the vertical temperature distribution in the water column up to 38 m above the seafloor was monitored. A stationary deep seafloor observatory system was also deployed to monitor hydrothermal activity in this site. The temperature logger array measured temperature anomalies, while the plumes from the vents passed through the array. Because the temperature anomalies were measured in only specific current directions, we identified one of the vents as the source. Heat flux from the vent was estimated by applying a plume model in crossflow in a density-stratified environment. The average heat flux from September 13 to October 18, 1997 was 39 MW. This heat flux is as same order as those of high-temperature black smokers, indicating that a large volume flux was discharged from the vent (1.9 m3/s). Previous observations found many similar warm water flow vents along the spreading axis between 17°20′ S–30′ S. The total heat flux was estimated to be at least a few hundred mega-watts. This venting style would contribute to form effluent hydrothermal plumes extended above the spreading axis. 相似文献
7.
In the 1974 eclipse of Zeta Aurigae the satellite line of the Cai intercombination line at 6572 Å appeared in all the phases observed, i.e., near the mid-eclipse and egress, although its equivalent width, 100–200 mÅ, and velocity deviation, –20 im s–1, from the principal line were considerably less than those for the satellite line found just after the fourth contact of the 1971–72 eclipse. 31 Cygni also showed a similar satellite line to Zeta Aurigae's in the 1974 eclipse, not only in the 1972 eclipse but also outside the eclipse. These satellite lines should be due to the circumstellar gas expanding from the binary systems. 相似文献
8.
Shusaku Inoue Anil C. Wijeyewickrema Hiroyuki Matsumoto Hiroyuki Miura Priyantha Gunaratna Manoj Madurapperuma Toru Sekiguchi 《Pure and Applied Geophysics》2007,164(2-3):395-411
The December 26, 2004 Sumatra-Andaman earthquake that registered a moment magnitude (Mw) of 9.1 was one of the largest earthquakes in the world since 1900. The devastating tsunami that resulted from this earthquake
caused more casualties than any previously reported tsunami. The number of fatalities and missing persons in the most seriously
affected countries were Indonesia - 167,736, Sri Lanka - 35,322, India - 18,045 and Thailand - 8,212. This paper describes
two field visits to assess tsunami effects in Sri Lanka by a combined team of Japanese and Sri Lankan researchers. The first
field visit from December 30, 2004 – January 04, 2005 covered the western and southern coasts of Sri Lanka including the cities
of Moratuwa, Beruwala, Bentota, Pereliya, Hikkaduwa, Galle, Talpe, Matara, Tangalla and Hambantota. The objectives of the
first field visit were to investigate the damage caused by the tsunami and to obtain eyewitness information about wave arrival
times. The second field visit from March 10–18, 2005 covered the eastern and southern coasts of Sri Lanka and included Trincomalee,
Batticaloa, Arugam Bay, Yala National Park and Kirinda. The objectives of the second visit were mainly to obtain eyewitness
information about wave arrival times and inundation data, and to take relevant measurements using GPS instruments. 相似文献
9.
Temporal variations of area of the North Pacific Intermediate Water (NPIW), in the repeat hydrographic section along 137°E
meridian conducted by the Japan Meteorological Agency, are investigated using the de-trended variables from 1972 to 2008.
Variations of NPIW area show a clear quasi-decadal (about 10 years) modulation and it is caused by the vertical displacement
of isopycnal surfaces in the lower portion of NPIW around the northern boundary of its distribution (30–32°N): The downward
(upward) movement of isopycnal surfaces in the lower portion of NPIW as a result of the first-mode baroclinic ocean response
stretches (shrinks) the density layer equivalent of NPIW and causes strengthening (weakening) of westward flows associated
with the Kuroshio Counter Current, and then it can induce an increase (decrease) of volume transport of NPIW from the east.
Consequently, the NPIW northern boundary shifts northward (southward) and an increase (decrease) of the NPIW area is induced.
Large-scale atmospheric forcing controlling the vertical displacements of isopycnal surfaces is explored using a wind-driven
hindcast ocean model. The vertical displacements stem from the first-mode baroclinic ocean response to the two types of Aleutian
Low (AL) activities: in particular, the meridional movement of the AL imparts more potential influence on them than the AL
intensity variation does. 相似文献
10.
Temporal variations of the net Kuroshio transport and its relation to atmospheric variations 总被引：1，自引：0，他引：1
Shusaku Sugimoto Kimio Hanawa Kumiko Narikiyo Megumi Fujimori Toshio Suga 《Journal of Oceanography》2010,66(5):611-619
Temporal variations of the net Kuroshio transport are investigated using long-term hydrographic data from repeat section of
the 137°E meridian from the south of Japan (34°N) to New Guinea (1°S) conducted by the Japan Meteorological Agency. In this
study, boundaries of the Kuroshio and the Kuroshio Counter Current (KCC) are defined based on the sea surface dynamic height
distribution. Westward flows associated with the KCC and cold-core eddy north of the Kuroshio are removed from the eastward
flow associated with the Kuroshio in order to estimate the net Kuroshio transport strictly. The net Kuroshio transport reveals
low-frequency variations: significant signals on a decadal (about 10-year) timescale. The variations of net Kuroshio transport
are predominantly caused by changes in the magnitude of oceanic current speed fields associated with a vertical movement of
the main pycnocline depth around the southern boundary of the Kuroshio: deepening of the main pycnocline around the southern
boundary of the Kuroshio forms a sharp northern upward-tilting slope of the isopycnal surfaces at the Kuroshio region, and
eventually the net Kuroshio transport increases together with the Kuroshio eastward transport. By using a wind-driven hindcast
model, it is found that the main pycnocline depth variation results from the first-mode baroclinic Rossby waves attributable
to two types of Aleutian Low (AL) changes: a change in the magnitude of AL and meridional movement of AL. 相似文献