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Hiroshi Taniguchi

Bio: Hiroshi Taniguchi is an academic researcher from University of Hawaii at Manoa. The author has contributed to research in topics: Monte Carlo method & Heat transfer. The author has an hindex of 14, co-authored 41 publications receiving 682 citations. Previous affiliations of Hiroshi Taniguchi include Hokkaido University & Japan Agency for Marine-Earth Science and Technology.

Papers
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Journal ArticleDOI
TL;DR: In this article, the forecast skill of the Madden-Julian Oscillation (MJO) observed during the period of DYNAMO (Dynamics of the MJO)/CINDY (Cooperative Indian Ocean Experiment on Intraseasonal Variability in Year 2011) field campaign was assessed.
Abstract: The present study assesses the forecast skill of the Madden–Julian Oscillation (MJO) observed during the period of DYNAMO (Dynamics of the MJO)/CINDY (Cooperative Indian Ocean Experiment on Intraseasonal Variability in Year 2011) field campaign in the GFS (NCEP Global Forecast System), CFSv2 (NCEP Climate Forecast System version 2) and UH (University of Hawaii) models, and revealed their strength and weakness in forecasting initiation and propagation of the MJO. Overall, the models forecast better the successive MJO which follows the preceding event than that with no preceding event (primary MJO). The common modeling problems include too slow eastward propagation, the Maritime Continent barrier and weak intensity. The forecasting skills of MJO major modes reach 13, 25 and 28 days, respectively, in the GFS atmosphere-only model, the CFSv2 and UH coupled models. An equal-weighted multi-model ensemble with the CFSv2 and UH models reaches 36 days. Air–sea coupling plays an important role for initiation and propagation of the MJO and largely accounts for the skill difference between the GFS and CFSv2. A series of forecasting experiments by forcing UH model with persistent, forecasted and observed daily SST further demonstrate that: (1) air–sea coupling extends MJO skill by about 1 week; (2) atmosphere-only forecasts driven by forecasted daily SST have a similar skill as the coupled forecasts, which suggests that if the high-resolution GFS is forced with CFSv2 forecasted daily SST, its forecast skill can be much higher than its current level as forced with persistent SST; (3) atmosphere-only forecasts driven by observed daily SST reaches beyond 40 days. It is also found that the MJO–TC (Tropical Cyclone) interactions have been much better represented in the UH and CFSv2 models than that in the GFS model. Both the CFSv2 and UH coupled models reasonably well capture the development of westerly wind bursts associated with November 2011 MJO and the cyclogenesis of TC05A in the Indian Ocean with a lead time of 2 weeks. However, the high-resolution GFS atmosphere-only model fails to reproduce the November MJO and the genesis of TC05A at 2 weeks’ lead. This result highlights the necessity to get MJO right in order to ensure skillful extended-range TC forecasting.

97 citations

Journal ArticleDOI
TL;DR: The importance of using dedicated high-end computing resources to enable high spatial resolution in global climate models and advance knowledge of the climate system has been evaluated in an international collaboration called Project Athena.
Abstract: The importance of using dedicated high-end computing resources to enable high spatial resolution in global climate models and advance knowledge of the climate system has been evaluated in an international collaboration called Project Athena. Inspired by the World Modeling Summit of 2008 and made possible by the availability of dedicated high-end computing resources provided by the National Science Foundation from October 2009 through March 2010, Project Athena demonstrated the sensitivity of climate simulations to spatial resolution and to the representation of subgrid-scale processes with horizontal resolutions up to 10 times higher than contemporary climate models. While many aspects of the mean climate were found to be reassuringly similar, beyond a suggested minimum resolution, the magnitudes and structure of regional effects can differ substantially. Project Athena served as a pilot project to demonstrate that an effective international collaboration can be formed to efficiently exploit dedicated sup...

91 citations

Book
01 Jan 1995
TL;DR: In this paper, the authors define the principles of radiation, thermal radiation radiation heat transfer, formulation methods of solution special treatises, and applications of the Monte Carlo method for two-dimensional systems.
Abstract: Part 1 Principles of radiation: thermal radiation radiation heat transfer. Part 2 Principles of Monte Carlo methods: formulation methods of solution special treatises. Part 3 Applications of the Monte Carlo method: two-dimensional systems some industrial applications references applications on disk list of variables in computer programs.

89 citations

Journal ArticleDOI
TL;DR: In this paper, the environmental field of tropical cyclogenesis over the Bay of Bengal is analyzed for the extended summer monsoon season (approximately May-November) using best-track and reanalysis data.
Abstract: The environmental field of tropical cyclogenesis over the Bay of Bengal is analyzed for the extended summer monsoon season (approximately May–November) using best-track and reanalysis data. Genesis potential index (GPI) is used to assess four possible environmental factors responsible for tropical cyclogenesis: lower-tropospheric absolute vorticity, vertical shear, potential intensity, and midtropospheric relative humidity. The climatological cyclogenesis is active within high GPI in the premonsoon (~May) and postmonsoon seasons (approximately October–November), which is attributed to weak vertical shear. The genesis of intense tropical cyclone is suppressed within the low GPI in the mature monsoon (approximately June–September), which is due to the strong vertical shear. In addition to the climatological seasonal transition, the authors’ composite analysis based on tropical cyclogenesis identified a high GPI signal moving northward with a periodicity of approximately 30–40 days, which is associat...

67 citations

Journal ArticleDOI
TL;DR: In this paper, detailed Madden-Julian oscillation (MJO) characteristics in the two 30-day integrations of the global cloud-system-resolving Nonhydrostatic Icosahedral Atmospheric Model (NICAM) using the all-season real-time multivariate MJO index of Wheeler and Hendon were revealed.
Abstract: This study discloses detailed Madden‐Julian oscillation (MJO) characteristics in the two 30-day integrations of the global cloud-system-resolving Nonhydrostatic Icosahedral Atmospheric Model (NICAM) using the allseason real-time multivariate MJO index of Wheeler and Hendon. The model anomaly is derived by excluding the observed climatology because the simulation is sufficiently realistic. Results show that the MJO has a realistic evolution in amplitude pattern, geographical locations, eastward propagation, and baroclinic- and westwardtilted structures. In the central Indian Ocean, convection develops with the low-level easterly wind anomaly then matures where the low-level easterly and westerly anomalies meet. Anomalous moisture tilts slightly with height. In contrast, over the western Pacific, the convection grows with a low-level westerly anomaly. Moisture fluctuations, leading convection in eastward propagation, tilt clearly westward with height. The frictional moisture convergence mechanism operates to maintain the MJO. Such success can be attributed to the explicit representation of the interactions between convection and large-scale circulations. The simulated event, however, grows faster in phases 2 and 3, and peaks with 30% higher amplitude than that observed, although the 7-km version shows slight improvement. The fast-growth phases are induced by the fast-growing low-level convergence in the Indian Ocean and the strongly biased ITCZ in the west Pacific when the model undergoes a spinup. The simulated OLR has a substantial bias in the tropics. Possible solutions to the deficiencies are discussed.

56 citations


Cited by
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TL;DR: The High-ResMIP (High-resolution Model Intercomparison Project) as mentioned in this paper is a multi-model approach to the systematic investigation of the impact of horizontal resolution on the simulated mean climate and its variability.
Abstract: . Robust projections and predictions of climate variability and change, particularly at regional scales, rely on the driving processes being represented with fidelity in model simulations. The role of enhanced horizontal resolution in improved process representation in all components of the climate system is of growing interest, particularly as some recent simulations suggest both the possibility of significant changes in large-scale aspects of circulation as well as improvements in small-scale processes and extremes. However, such high-resolution global simulations at climate timescales, with resolutions of at least 50 km in the atmosphere and 0.25° in the ocean, have been performed at relatively few research centres and generally without overall coordination, primarily due to their computational cost. Assessing the robustness of the response of simulated climate to model resolution requires a large multi-model ensemble using a coordinated set of experiments. The Coupled Model Intercomparison Project 6 (CMIP6) is the ideal framework within which to conduct such a study, due to the strong link to models being developed for the CMIP DECK experiments and other model intercomparison projects (MIPs). Increases in high-performance computing (HPC) resources, as well as the revised experimental design for CMIP6, now enable a detailed investigation of the impact of increased resolution up to synoptic weather scales on the simulated mean climate and its variability. The High Resolution Model Intercomparison Project (HighResMIP) presented in this paper applies, for the first time, a multi-model approach to the systematic investigation of the impact of horizontal resolution. A coordinated set of experiments has been designed to assess both a standard and an enhanced horizontal-resolution simulation in the atmosphere and ocean. The set of HighResMIP experiments is divided into three tiers consisting of atmosphere-only and coupled runs and spanning the period 1950–2050, with the possibility of extending to 2100, together with some additional targeted experiments. This paper describes the experimental set-up of HighResMIP, the analysis plan, the connection with the other CMIP6 endorsed MIPs, as well as the DECK and CMIP6 historical simulations. HighResMIP thereby focuses on one of the CMIP6 broad questions, “what are the origins and consequences of systematic model biases?”, but we also discuss how it addresses the World Climate Research Program (WCRP) grand challenges.

608 citations

Journal ArticleDOI
TL;DR: In this article, model projections of tropical cyclone activity response to anthropogenic warming in climate models are assessed and observations, theory, and models, with increasing robustness, indicate that tropical cyclones respond well to global warming.
Abstract: Model projections of tropical cyclone (TC) activity response to anthropogenic warming in climate models are assessed. Observations, theory, and models, with increasing robustness, indicate ...

536 citations

Journal ArticleDOI
TL;DR: In this article, the authors consider the issues of bias correction and make recommendations for research to overcome model biases, and conclude that bias correction cannot overcome major model errors, and naive application might result in ill-informed adaptation decisions.
Abstract: Biases in climate model simulations introduce biases in subsequent impact simulations. Therefore, bias correction methods are operationally used to post-process regional climate projections. However, many problems have been identified, and some researchers question the very basis of the approach. Here we demonstrate that a typical cross-validation is unable to identify improper use of bias correction. Several examples show the limited ability of bias correction to correct and to downscale variability, and demonstrate that bias correction can cause implausible climate change signals. Bias correction cannot overcome major model errors, and naive application might result in ill-informed adaptation decisions. We conclude with a list of recommendations and suggestions for future research to reduce, post-process, and cope with climate model biases. Bias correction methods aim to remove introduced bias for climate model simulations; however, improper use can result in spurious climate signals. This Perspective considers the issues of bias correction and makes recommendations for research to overcome model biases.

341 citations

Journal ArticleDOI
TL;DR: The use of the Monte Carlo method in radiative heat transfer is reviewed in this paper, where surface-surface, enclosure, and participating media problems are considered, as well as the effects of using parallel algorithms.
Abstract: The use of the Monte Carlo method in radiative heat transfer is reviewed. The review covers surface-surface, enclosure, and participating media problems. Discussio. is included of research on the fundamentals of the method and on applications to surface-surface interchange in enclosures, exchange between surfaces with roughness characteristics, determination of configuration factors, inverse design, transfer through packed beds and fiber layers, participating media, scattering, hybrid methods, spectrally dependent problems including media with line structure, effects of using parallel algorithms, practical applications, and extensions of the method. Conclusions are presented on needed future work and the place of Monte Carlo techniques in radiative heat transfer computations

331 citations

Journal ArticleDOI
TL;DR: In this article, a synthesis of the influences of a changing climate on storm tracks reveals competing effects on meridional temperature gradients, which make projections difficult, making it difficult to make predictions.
Abstract: Extratropical storms contribute to precipitation, wind and temperature extremes. A synthesis of the influences of a changing climate on storm tracks reveals competing effects on meridional temperature gradients, which make projections difficult.

323 citations