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  • 1
    Online Resource
    Online Resource
    Image_1.PDF
    Frontiers Media SA ; 2021
    In:  Frontiers in Marine Science Vol. 8 ( 2021-9-8)
    Details
    In: Frontiers in Marine Science, Frontiers Media SA, Vol. 8 ( 2021-9-8)
    Abstract: The water mass structure in Suruga Bay is strongly influenced by open-ocean water. In particular, it is suggested that intermittent intrusions of the Kuroshio water generate characteristic circulations in the surface layer of the bay. In this study, we investigated the processes of the intrusions of open-ocean water into the bay and related generation of bay-scale cyclonic and anti-cyclonic circulation patterns. In doing so, we used an ocean simulation product with observational data constraint on meso and larger scales and with a resolution fine enough to resolve the smaller-scale intrusion structure. Cyclonic and anti-cyclonic circulation patterns as suggested by previous observational studies were detected as positive and negative first leading empirical orthogonal function (EOF) modes of the velocity field in Suruga Bay. The time scale of occurrences of these patterns was estimated as about 1 month, which was consistent with short-term Kuroshio fluctuations as reported in previous studies. Conditions favorable for generating these patterns were analyzed for three typical Kuroshio path periods individually. As suggested by previous studies, relatively strong northward flow to the west of Zeni-su generally promoted the open-ocean water intrusions into the eastern bay mouth, leading the cyclonic circulation in Suruga Bay. Our results showed that the correlation of this relation was significant for each Kuroshio path period. The open-ocean water intrusion increased the surface-layer temperature in Suruga Bay by about 0.7°C on average. On the other hand, the anti-cyclonic circulation pattern in Suruga Bay tended to be generated with relatively weak northward flow to the west of Zeni-su during the large meander Kuroshio path period, whereas this relation was rather weak during other periods. These results were mostly supported by available observations and would be useful for integrating our understanding of the influences of the western boundary current fluctuations on the circulation and temperature variations in proximal bays.
    Type of Medium: Online Resource
    ISSN: 2296-7745
    URL: Article
    URL: Article
    DOI: 10.3389/fmars.2021.721500
    DOI: 10.3389/fmars.2021.721500.s001
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2021
    detail.hit.zdb_id: 2757748-X
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  • 2
    Online Resource
    Online Resource
    Energy Flow Diagnosis of ENSO from an Ocean Reanalysis
    American Meteorological Society ; 2021
    In:  Journal of Climate Vol. 34, No. 10 ( 2021-05), p. 4023-4042
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 34, No. 10 ( 2021-05), p. 4023-4042
    Abstract: A method is introduced for diagnosing the time evolution of wave energy associated with ENSO from an ocean reanalysis. In the diagnosis, time changes of kinetic and available potential energy are mainly represented by energy inputs caused by surface wind stress and horizontal energy fluxes for each vertically decomposed normal mode. The resulting time evolutions of the wave energy and vertical thermocline displacements in the 1997/98 and 2014–16 El Niño events are consistent with our previous knowledge of these events. Further, our result indicated that representation of several vertical modes is necessary to reproduce the broadly distributed downward thermocline displacements in the central to eastern equatorial Pacific, generated by a westerly wind event in the western equatorial Pacific (e.g., in March 1997), that are preconditioning for El Niño development. In addition, we investigated the wave energy budget, including the influence of data assimilation, on the complicated time evolution of equatorial thermocline displacements caused by repeated westerly and easterly wind events during the 2014–16 El Niño event. Our result suggests that noise from a momentum imbalance near the equator associated with data assimilation, which possibly affected the El Niño prediction failure in 2014, was much reduced by our developed ocean data assimilation system and reanalysis. This study, which provides a new connection between the theoretical works and reanalysis products that use sophisticated systems for synthesizing OGCMs and observations, should be useful for climate research and operational communities interested in ENSO.
    Type of Medium: Online Resource
    ISSN: 0894-8755 , 1520-0442
    URL: Article
    DOI: 10.1175/JCLI-D-20-0704.1
    RVK:
    UA 4548
    Language: Unknown
    Publisher: American Meteorological Society
    Publication Date: 2021
    detail.hit.zdb_id: 246750-1
    detail.hit.zdb_id: 2021723-7
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  • 3
    Online Resource
    Online Resource
    Effects of Inclusion of Adjoint Sea Ice Rheology on Backward Sensitivity Evolution Examined Using an Adjoint Ocean–Sea Ice Model
    American Meteorological Society ; 2019
    In:  Monthly Weather Review Vol. 147, No. 6 ( 2019-06), p. 2145-2162
    Details
    In: Monthly Weather Review, American Meteorological Society, Vol. 147, No. 6 ( 2019-06), p. 2145-2162
    Abstract: As part of the ongoing development of an ocean data assimilation system for operational ocean monitoring and seasonal prediction, an adjoint sea ice model was developed that incorporates sea ice rheology, which was omitted from previously developed adjoint models to avoid model instability. The newly developed adjoint model was merged with the existing system to construct a global ocean–sea ice adjoint model. A series of sensitivity experiments, in which idealized initial values were given for the adjoint sea ice area fraction and thickness, were conducted, with particular attention to the differences between the cases with free-drift approximation in the adjoint sea ice model as in previous studies and with full sea ice dynamics including rheology. The internal stress effects represented in the adjoint rheology induced remarkable differences in the evolution of the initialized and generated adjoint variables, such as for the sea ice velocity by O (10 2 ) in magnitude, which highlighted the importance of the adjoint rheology in the central Arctic Ocean. In addition, sensitivities with respect to the nonprognostic variables associated with the sea ice dynamics were obtained only through the adjoint rheology. These results suggested a potential for providing an improved global atmosphere–ocean–sea ice state estimation through a four-dimensional variational approach with the adjoint sea ice model as developed in this study.
    Type of Medium: Online Resource
    ISSN: 0027-0644 , 1520-0493
    URL: Article
    DOI: 10.1175/MWR-D-18-0198.1
    RVK:
    RA 1000
    Language: Unknown
    Publisher: American Meteorological Society
    Publication Date: 2019
    detail.hit.zdb_id: 2033056-X
    detail.hit.zdb_id: 202616-8
    SSG: 14
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  • 4
    Online Resource
    Online Resource
    Construction of 714 MHz HOM-free accelerating cavities
    International Union of Crystallography (IUCr) ; 1998
    In:  Journal of Synchrotron Radiation Vol. 5, No. 3 ( 1998-05-01), p. 386-388
    Details
    In: Journal of Synchrotron Radiation, International Union of Crystallography (IUCr), Vol. 5, No. 3 ( 1998-05-01), p. 386-388
    Abstract: A new `higher-order-mode (HOM)-free' accelerating cavity has been developed which can provide an accelerating voltage of more than 400 kV per cavity at a frequency of 714 MHz. The harmful HOMs in the cavities, which can induce beam instabilities at high beam currents, were heavily damped by using four special waveguide ports and broadband microwave loads. Two cavities of this design were installed in the 1.54 GeV accelerator test facility (ATF) damping ring at KEK, and successfully stored beams. This cavity will also be very useful for synchrotron light sources. The basic design, characteristics of HOMs and construction of this cavity are reported.
    Type of Medium: Online Resource
    ISSN: 0909-0495
    URL: Article
    DOI: 10.1107/S0909049597015343
    Language: Unknown
    Publisher: International Union of Crystallography (IUCr)
    Publication Date: 1998
    detail.hit.zdb_id: 2021413-3
    SSG: 13
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  • 5
    Online Resource
    Online Resource
    Beam Test of Multi-Bunch Energy Compensation System in the Accelerator Test Facility at KEK
    IOP Publishing ; 2004
    In:  Japanese Journal of Applied Physics Vol. 43, No. 8R ( 2004-08-01), p. 5617-
    Details
    In: Japanese Journal of Applied Physics, IOP Publishing, Vol. 43, No. 8R ( 2004-08-01), p. 5617-
    Abstract: A beam test of the multi-bunch energy compensation system (ECS) was performed using the Δ F method with the 2856±4.327 MHz accelerating structures in the accelerator test facility (ATF) at KEK. The 1.54 GeV S-band linac of the ATF was designed to accelerate a multi-bunch beam that consists of 20 bunches with 2.8 ns spacing. The multi-bunch beam with 2.0×10 10 electrons/bunch has an energy deviation of about 8.5% at the end of the linac due to transient beam loading without ECS. The ATF linac is the injector of the ATF damping ring (DR), whose energy acceptance is ±0.5%. The beam loading compensation system is necessary in the ATF linac for the successful injection of multi-bunch into DR. The rf system of the linac consists of 8 regular rf units with the SLED system and 2 ECS rf units without the SLED system. The accelerating structures of the regular units are driven at 2856 MHz and the 2 ECS structures are operated with slightly different rf frequencies of 2856±4.327 MHz. In the beam test, we have succeeded in compressing the multi-bunch energy spread within the energy acceptance of the DR using Δ F ECS. The principle of the beam loading compensation system of KEK-ATF and the experimental results are described in this paper.
    Type of Medium: Online Resource
    ISSN: 0021-4922 , 1347-4065
    URL: Article
    DOI: 10.1143/JJAP.43.5617
    RVK:
    UA 4210.1
    RVK:
    UA 4210.2
    RVK:
    UA 4210
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2004
    detail.hit.zdb_id: 218223-3
    detail.hit.zdb_id: 797294-5
    detail.hit.zdb_id: 2006801-3
    detail.hit.zdb_id: 797295-7
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  • 6
    Online Resource
    Online Resource
    Miscibility Control of Polystyrene and 4-Pentyl-4'-Cyanobiphenyl by Partial p-Hydroxymethylation
    Society of Materials Science, Japan ; 2009
    In:  Journal of the Society of Materials Science, Japan Vol. 58, No. 1 ( 2009), p. 47-52
    Details
    In: Journal of the Society of Materials Science, Japan, Society of Materials Science, Japan, Vol. 58, No. 1 ( 2009), p. 47-52
    Type of Medium: Online Resource
    ISSN: 1880-7488 , 0514-5163
    URL: Article
    DOI: 10.2472/jsms.58.47
    Language: Unknown
    Publisher: Society of Materials Science, Japan
    Publication Date: 2009
    detail.hit.zdb_id: 2269568-0
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  • 7
    Online Resource
    Online Resource
    Evaluation of a global ocean reanalysis generated by a global ocean data assimilation system based on a four-dimensional variational (4DVAR) method
    Frontiers Media SA ; 2023
    In:  Frontiers in Climate Vol. 4 ( 2023-1-10)
    Details
    In: Frontiers in Climate, Frontiers Media SA, Vol. 4 ( 2023-1-10)
    Abstract: Japan Meteorological Agency (JMA) started to use a new global ocean data assimilation system for the operational seasonal predictions in February 2022. The system is composed of two subsystems with non-eddy-permitting (lower) and eddy-permitting (higher) resolutions. The lower-resolution subsystem adopts a four-dimensional variational (4DVAR) method to optimize the temperature and salinity fields, and the data-assimilated fields are downscaled into the higher-resolution subsystem using incremental analysis updates. The impact of introducing the 4DVAR method in the new ocean data assimilation system is investigated through the comparison of a regular reanalysis run of the system using the 4DVAR method with another run using a three-dimensional variational (3DVAR) method. A comparison of the temperature fields before the downscaling between the two reanalysis runs indicates that the 4DVAR method can more effectively reduce the misfits between the model field and assimilated observation data. However, the increase of the temperature root mean square difference (RMSD) relative to independent Argo float data, along with the larger variance, for the run with the 4DVAR method reveals that the 4DVAR method adjusts the temperature field more significantly but the adjustments are inconsistent with the independent data due to insufficient model physics and resolution. The increase of the RMSD is mitigated after the assimilated fields are downscaled into the higher-resolution subsystem. The 4DVAR method reduces the bias and RMSD of temperature relative to the independent data along the thermocline, as well as near the surface, in the equatorial vertical section, which is expected to affect the prediction of El Niño-Southern Oscillation (ENSO).
    Type of Medium: Online Resource
    ISSN: 2624-9553
    URL: Article
    DOI: 10.3389/fclim.2022.1019673
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2023
    detail.hit.zdb_id: 2986708-3
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