Fujii Yosuke

Fujii Yosuke
Meteorological Research Institute, Japan Meteorological Agency · Department of Atmosphere Ocean and Earth System Modeling Research

Ph. D.

About

90
Publications
15,056
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Introduction
Fujii Yosuke currently works at the Oceanographic Research Dep., Meteorological Research Institute, Japan Meteorological Agency. Fujii does research in Oceanography. Their most recent publication is 'Coupled Data Assimilation for Integrated Earth System Analysis and Prediction: Goals, Challenges, and Recommendations'.
Additional affiliations
April 2000 - present
Meteorological Research Institute, Japan Meteorological Agency
Position
  • Senior Research Official

Publications

Publications (90)
Article
Full-text available
To evaluate the atmosphere–ocean coupled data assimilation system developed at the Meteorological Research Institute, the lead-lag relation between the intraseasonal variations (with a time scale of 20–100 days) in precipitation and sea surface temperature (SST) is examined in the tropics. It is shown that the relationship over the tropical western...
Article
A coupled atmosphere‐ocean data assimilation system, the Meteorological Research Institute‐Coupled Data Assimilation System Version 1 (MRI‐CDA1), was developed based on the coupled atmosphere‐ocean general circulation model and separated atmosphere and ocean analysis routines operated by the Japan Meteorological Agency (JMA). To implement coupled a...
Article
One effective data assimilation/inversion method is the four‐dimensional variational method (4D‐Var). However, it is a non‐trivial task for a conventional 4D‐Var to estimate a posterior error covariance matrix. This study proposes a method to estimate a posterior error covariance matrix applied to the linear inverse problem of an atmospheric consti...
Poster
JMA operates global ocean data assimilation system in order to monitor the ocean state especially in the equatorial region and to provide ocean initial conditions for seasonal forecasting system. This talk will show a current status of development of the next-generation global ocean data assimilation system (MOVE-G3) in JMA/MRI. MOVE-G3 adopts a f...
Article
We developed a new system to monitor and forecast coastal and open-ocean states around Japan for operational use by the Japan Meteorological Agency. The system consists of an eddy-resolving analysis model based on four-dimensional variational assimilation and a high (2-km) resolution forecast model covering Japanese coastal areas that incorporates...
Article
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Subseasonal-to-seasonal (S2S) forecasts have the potential to provide advance information about weather and climate events. The high heat capacity of water means that the subsurface ocean stores and re-releases heat (and other properties) and is an important source of information for S2S forecasts. However, the subsurface ocean is challenging to ob...
Article
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This paper summarizes recent efforts on Observing System Evaluation (OS-Eval) by the Ocean Data Assimilation and Prediction (ODAP) communities such as GODAE OceanView and CLIVAR-GSOP. It provides some examples of existing OS-Eval methodologies, and attempts to discuss the potential and limitation of the existing approaches. Observing System Experim...
Article
Full-text available
Developments in observing system technologies and ocean data assimilation (DA) are symbiotic. New observation types lead to new DA methods and new DA methods, such as coupled DA, can change the value of existing observations or indicate where new observations can have greater utility for monitoring and prediction. Practitioners of DA are encouraged...
Poster
This talk will show a current status of development of next-generation global ocean data assimilation system (MOVE-G3) in JMA/MRI. MOVE-G3 adopts a four-dimensional variational (4DVAR) scheme, rather than current operational three-dimensional variational (3DVAR) scheme, and a sea-ice assimilation component is newly introduced into the system. The...
Article
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 exis...
Poster
A global ocean data assimilation system based on a 4DVAR method is developed for improving coupled predictions in Japan Meteorological Agency (JMA). The 4DVAR analysis field with a coarse horizontal resolution (1° zonal and 0.3-0.5° meridional) is used for IAU initialization with a higher eddy-permitting resolution (0.25° zonal and meridional). Tem...
Poster
In this talk, the current development status of next seasonal ensemble prediction system (JMA/MRI-CPS3: Japan Meteorological Agency/Meteorological Research Institute-Coupled Prediction System version 3) will be presented. As a new version of the JMA/MRI-CPS2, currently operated for the purpose of three-month, warm/cold season, and El Niño predictio...
Poster
Since the first implementation of ENSO forecast system in late 1990s, continuous effort has been made to improve its accuracy and reliability at JMA. For the next version to be released in 2021-2022, we plan to introduce ocean four-dimensional variational data assimilation method (4DVAR) in search for reducing large forecast bust as such happened f...
Article
Full-text available
This paper describes the Japan Meteorological Agency/Meteorological Research Institute-Coupled Prediction System version 2 (JMA/MRI-CPS2), which was put into operation in June 2015 for the purpose of performing seasonal predictions. JMA/MRI-CPS2 has various upgrades from its predecessor, JMA/MRI-CPS1, including improved resolution and physics in it...
Article
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An ensemble of nine operational ocean reanalyses (ORAs) is now routinely collected, and is used to monitor the consistency across the tropical Pacific temperature analyses in real-time in support of ENSO monitoring, diagnostics, and prediction. The ensemble approach allows a more reliable estimate of the signal as well as an estimation of the noise...
Article
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The mean and variability of the Atlantic meridional overturning circulation (AMOC), as represented in six ocean reanalysis products, are analyzed over the period 1960–2007. Particular focus is on multi-decadal trends and interannual variability at 26.5°N and 45°N. For four of the six reanalysis products, corresponding reference simulations obtained...
Article
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Sixteen monthly air–sea heat flux products from global ocean/coupled reanalyses are compared over 1993–2009 as part of the Ocean Reanalysis Intercomparison Project (ORA-IP). Objectives include assessing the global heat closure, the consistency of temporal variability, comparison with other flux products, and documenting errors against in situ flux...
Article
Full-text available
Many institutions worldwide have developed ocean reanalyses systems (ORAs) utilizing a variety of ocean models and assimilation techniques. However, the quality of salinity reanalyses arising from the various ORAs has not yet been comprehensively assessed. In this study, we assess the upper ocean salinity content (depth-averaged over 0–700 m) from...
Article
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Ocean–sea ice reanalyses are crucial for assessing the variability and recent trends in the Arctic sea ice cover. This is especially true for sea ice volume, as long-term and large scale sea ice thickness observations are inexistent. Results from the Ocean ReAnalyses Intercomparison Project (ORA-IP) are presented, with a focus on Arctic sea ice fie...
Article
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In the original publication of the article, Fig. 11 was published incorrectly. The correct version of Fig. 11 is provided here
Article
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A four-dimensional variational method (4D-Var) is a popular technique for source/sink inversions of atmospheric constituents, but it is not without problems. Using an icosahedral grid transport model and the 4D-Var method, a new atmospheric greenhouse gas (GHG) inversion system has been developed. The system combines offline forward and adjoint mod...
Article
Full-text available
In 1995, the World Meteorological Organization (WMO) Second International Symposium on Assimilation of Observation in Meteorology and Oceanography was held in Tokyo, which initiated the Japanese Summer School on Data Assimilation. Over the past 20 years, the ocean data assimilation research community in Japan has accomplished remarkable achievement...
Article
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The Triangle Trans‐Ocean Buoy Network (TRITON) project by the Japan Agency for Marine-Earth Science and Technology began with deployment in the western tropical Pacific Ocean in 1998 and has shifted to steady, long-term observations since 1999. After on-site inter-comparison with the Autonomous Temperature Line Acquisition System mooring system of...
Article
Full-text available
This paper describes the operational seasonal prediction system of the Japan Meteorological Agency (JMA), the Japan Meteorological Agency/Meteorological Research Institute-Coupled Prediction System version 1 (JMA/MRI-CPS1), which was in operation at JMA during the period between February 2010 and May 2015. The predictive skill of the system was ass...
Article
Full-text available
A 4-dimensional variational method (4D-Var) is a popular technique for inverse modeling of atmospheric constituents, but it is not without problems. Using an icosahedral grid transport model and the 4D-Var method, a new atmospheric greenhouse gas (GHG) inversion system has been developed. The system combines off-line forward and adjoint models with...
Article
Full-text available
We produced a four-dimensional variational ocean re-analysis for the Western North Pacific over 30 years (FORA-WNP30). It is the first-ever dataset covering the western North Pacific over 3 decades at eddy-resolving resolution. The four-dimensional variational analysis scheme version of the Meteorological Research Institute Multivariate Ocean Varia...
Article
We evaluate the mean circulation patterns, water mass distributions, and tropical dynamics of the North and Equatorial Pacific Ocean based on a suite of global ocean-sea ice simulations driven by the CORE-II atmospheric forcing from 1963-2007. The first three moments (mean, standard deviation and skewness) of sea surface height and surface temperat...
Article
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In this paper we compare the simulated Arctic Ocean in 15 global ocean–sea ice models in the framework of the Coordinated Ocean-ice Reference Experiments, phase II (CORE-II). Most of these models are the ocean and sea-ice components of the coupled climate models used in the Coupled Model Intercomparison Project Phase 5 (CMIP5) experiments. We mainl...
Article
The Arctic Ocean simulated in fourteen global ocean-sea ice models in the framework of the Coordinated Ocean-ice Reference Experiments, phase II (CORE-II) is analyzed in this study. The focus is on the Arctic liquid freshwater (FW) sources and freshwater content (FWC). The models agree on the interannual variability of liquid FW transport at the ga...
Article
Full-text available
The Arctic Ocean simulated in fourteen global ocean-sea ice models in the framework of the Coordinated Ocean-ice Reference Experiments, phase II (CORE II) is analyzed. The focus is on the Arctic sea ice extent, the solid freshwater (FW) sources and solid freshwater content (FWC). Available observations are used for model evaluation. The variability...
Article
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Simulated inter-annual to decadal variability and trends in the North Atlantic for the 1958–2007 period from twenty global ocean – sea-ice coupled models are presented. These simulations are performed as contributions to the second phase of the Coordinated Ocean-ice Reference Experiments (CORE-II). The study is Part II of our companion paper (Danab...
Article
A multivariate data assimilation experiment was conducted in order to improve the global representation of both the ocean and sea ice fields through the inclusion of sea ice concentration (SIC) data. Our method corrects the surface forcing and ocean temperature fields (as well as the SIC field) through the use of three-dimensional variational analy...
Article
Full-text available
Accurate knowledge of the location and magnitude of ocean heat content (OHC) variability and change is essential for understanding the processes that govern decadal variations in surface temperature, quantifying changes in the planetary energy budget, and developing constraints on the transient climate response to external forcings. We present an o...
Article
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The interannual-decadal variability of the wintertime mixed layer depths (MLDs) over the North Pacific is investigated from an empirical orthogonal function (EOF) analysis of an ensemble of global ocean reanalyses. The first leading EOF mode represents the interannual MLD anomalies centered in the eastern part of the central mode water formation re...
Article
Full-text available
This paper examines the difference in the Atlantic Meridional Overturning Circulation (AMOC) mean state between free and assimilative simulations of a common ocean model using a common interannual atmospheric forcing. In the assimilative simulation, the reproduction of cold cores in the Nordic Seas, which is absent in the free simulation, enhances...
Article
Full-text available
The dramatic reduction in the number of observation data from the Tropical Atmospheric Ocean (TAO)/ Triangle Trans-Ocean Buoy Network (TRITON) array since 2012 has given rise to a need to assess the impact of those data in ocean Data Assimilation (DA) systems. This paper provides a review of existing studies evaluating the impacts of data from the...
Article
The authors have developed an assimilation system toward coastal data assimilation around Japan, which consists of a four-dimensional variational (4DVAR) assimilation scheme with an eddy-resolving model in the western North Pacific (MOVE-4DVAR-WNP) and a fine-resolution coastal model covering the western part of the Japanese coastal region around t...
Article
Full-text available
The GODAE OceanView systems use various data assimilation algorithms, including 3DVar, EnOI, EnKF and the SEEK filter with a fixed basis, using different time windows. The main outputs of the operational data assimilation systems, the increments, have been compared for February 2014 in various regions. The eddy-permitting systems’ increments are si...
Article
Full-text available
Under GODAE OceanView the operational ocean modelling community has developed a suite of global ocean forecast, reanalysis and analysis systems. Each system has a critical dependence on ocean observations - routinely assimilating observations of in-situ temperature and salinity, and satellite sea-level anomaly and sea surface temperature. This pape...
Article
This study evaluates capability of the Argo observation network for monitoring ocean variation, especially for eddy-scale variation, by using an optimum interpolation (OI) procedure. Sea surface dynamic height anomalies (DHAs) are derived from Argo temperature and salinity profile data, and DHA fields are obtained by the OI based on the space-time...
Article
Full-text available
Intercomparison and evaluation of the global ocean surface mixed layer depth (MLD) fields estimated from a suite of major ocean syntheses are conducted. Compared with the reference MLDs calculated from individual profiles, MLDs calculated from monthly mean and gridded profiles show negative biases of 10–20 m in early spring related to the re-strati...
Article
Full-text available
Impacts of TAO/TRITON (TT) and Argo data in the tropical Pacific on the accuracy of temperature and salinity fields generated by a data-assimilation system for operational seasonal forecasts are examined through a series of observing system experiments. This study demonstrates positive impacts of both TT and Argo data, and that these observation ty...
Article
Full-text available
Quantifying the effect of the seawater density changes on sea level variability is of crucial importance for climate change studies, as the sea level cumulative rise can be regarded as both an important climate change indicator and a possible danger for human activities in coastal areas. In this work, as part of the Ocean Reanalysis Intercomparison...
Article
The impact of using sea surface salinity (SSS) data derived from the Aquarius satellite within a global ocean data assimilation system is investigated. In the central-eastern North Pacific, the more realistic SSS structures introduced by the Aquarius data also influence the salinity, temperature and potential vorticity fields obtained in the subsur...
Article
Uncertainty in ocean analysis methods and deficiencies in the observing system are major obstacles for the reliable reconstruction of the past ocean climate. The variety of existing ocean reanalyses is exploited in a multi-reanalysis ensemble to improve the ocean state estimation and to gauge uncertainty levels. The ensemble-based analysis of signa...
Article
Full-text available
Uncertainty in ocean analysis methods and deficiencies in the observing system are major obstacles for the reliable reconstruction of the past ocean climate. The variety of existing ocean reanalyses is exploited in a multi-reanalysis ensemble to improve the ocean state estimation and to gauge uncertainty levels. The ensemble-based analysis of signa...
Article
A consistency between seasonal fluctuation of actual sea surface height (SSH) and those caused by mass and density variations in gyre-scale regions is examined. The SSH obtained from satellite altimetry (altimetric SSH) is adopted as the actual SSH. SSH caused by mass variation (mass-related SSH) is simulated using a barotropic global ocean model f...
Article
Full-text available
Simulation characteristics from eighteen global ocean-sea-ice coupled models are presented with a focus on the mean Atlantic meridional overturning circulation (AMOC) and other related fields in the North Atlantic. These experiments use inter-annually varying atmospheric forcing data sets for the 60-year period from 1948 to 2007 and are performed a...
Article
Full-text available
Four-dimensional variational data assimilation (4D-Var) on a seasonal-to-interdecadal time scale under the existence of unstable modes can be viewed as an optimization problem of synchronized, coupled chaotic systems. The problem is tackled by adjusting initial conditions to bring all stable modes closer to observations and by using a continuous gu...
Article
This study develops a strategy for tracing a target water mass, and applies it to analyzing the pathway of the North Pacific Intermediate Water (NPIW) from the subarctic gyre to the northwestern part of the subtropical gyre south of Japan in a simulation of an ocean general circulation model. This strategy estimates the pathway of the water mass th...
Article
The present study focuses on the recent update of the global ocean data assimilation system in the Meteorological Research Institute (MR1). The model domain of the system is extended to cover the Arctic Ocean with advanced physical processes incorporated (e.g., sea ice). Compared with data-free simulation, data assimilation improves reproduction of...
Article
The decay mechanism of the 2004/05 Kuroshio large meander (LM) is examined using a data assimilation/prediction system. Assimilation results reveal detailed variations of the Kuroshio path during the LM period. The Kuroshio takes the typical LM in September 2004 to January 2005. The LM then moves eastward and starts crossing the Izu Ridge (IR) in l...
Article
We assess validity of a Gaussian error assumption, the basic assumption in data assimilation theory, and propose two kinds of constraints regarding non-Gaussian statistics. In the mixed water region (MWR) off the east coast of Japan exhibiting complicated frontal structures, a probability density function (PDF) of subsurface temperature shows doubl...
Article
This paper investigates the feasibility of an ocean data assimilation system to analyze the salinity variability associated with the barrier layer in the equatorial Pacific. In order to validate reproducibility of the temperature and salinity fields, we perform an assimilation run where some temperature and salinity observations by TRITON buoys and...
Article
Full-text available
Global ocean forecast systems, developed under the Global Ocean Data Assimilation Experiment (GODAE), can be used to assess the impact of different components of the Global Ocean Observing System (GOOS). GODAE systems can be exploited to help identify observational gaps and to ultimately improve the efficiency and effectiveness of the GOOS for cons...