Tomoya ShimuraKyoto University | Kyodai · Disaster Prevention Research Institute
Tomoya Shimura
Ph.D.
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147
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Introduction
Skills and Expertise
Additional affiliations
April 2015 - May 2016
April 2012 - March 2015
Publications
Publications (147)
Sea level rise and intensified storm surges due to climate change are assumed to increase the inundation risk in coastal areas. Climate change adaptation policies in Japan are being developed, but long-term changes in inundation risk have not yet been quantified. This study estimated the potential inundation risk areas considering sea level rise an...
Mangroves are vegetation unique to coastal areas and are expected to attenuate waves. However, the effect has not been quantified because of the complex shapes of prop roots. In this study, parameterization of the projected area of prop roots was conducted based on some systematic field observations. Using the parameterized tree shape, we performed...
The rising sea level poses a serious threat to Southeast Asia, endangering low-lying islands and coastal areas. Climate events like El Niño significantly influence the sea level changes and variability. However, Southeast Asia has a series of complex island structures located between the Indian and Pacific oceans, creating unique characteristics of...
We developed a system to assimilate the frequency spectrum observations of drifting buoys into the spectral wave model, WAVEWATCH III. We implemented the optimal interpolation as data assimilation method. We conducted typhoon wave simulations in the Western North Pacific, targeting Typhoon NANMADOL in 2022. The accuracy of wave simulations was esti...
A new tropical cyclone dataset for Japan under the 1.5K warming scenario was constructed using an objective cyclone tracking algorithm and the d4PDF (database for Policy Decision making for Future climate change). The d4PDF data for the 1.5K condition used in the tracking is limited to the Japan area, and we corrected for the effect of not being ab...
The extreme winds of tropical cyclones generate high waves over the ocean, causing severe damage to offshore facilities and coastal communities ¹ . Disaster mitigation requires accurate prediction and forecasting of the worst-class high waves. Furthermore, wave development, an entity of momentum loss from a tropical cyclone, determines the intensit...
Tropical cyclones are one of the most destructive natural phenomena, causing tremendous coastal disasters worldwide. The maximum intensity of tropical cyclones is determined by momentum and heat transfer at the air-sea interface. Momentum transfer corresponds to the momentum loss of tropical cyclones and, consequently, to the underlying ocean's mom...
This study aims to quantify the sensitivity of fault depth and rake to the coastal tsunami height. The target earthquake source is the subduction zone along the Nankai Trough, conditioned on the southwest of Japan. First, possible ranges of the fault parameters are investigated. The spatial distribution of fault depth is compared using existing two...
On January 15, 2022, at around 13:00 JST, a massive eruption occurred at Hunga Tonga-Hunga Ha’apai volcano in the Tonga Islands, South Pacific Ocean. The eruption was accompanied by rapid atmospheric pressure changes and tsunamis along the Pacific coast. Along the Japanese coast, tsunami waves were observed several hours before the expected arrival...
This study estimates the spatio-temporal changes in the whitecap coverage process from the development of whitecaps associated with wave breaking to the residual foam, and discusses the statistical characteristics of the whitecap coverage process by using sea surface image observations for storm surge events associated with the passage of a bomb cy...
The intensity characteristics of typhoons under special conditions were evaluated using an original climate experiment based on a model combining a slab ocean model with a global atmospheric climate model (MRI-AGCM) from the Meteorological Research Institute of the Japan Meteorological Agency. Seventy years of September average SSTs were analyzed,...
This study shows future changes in the maximum potential intensity of tropical cyclones (TC) based on the MPI (Maximum Potential Intensity) theory. In addition, we have clarified the accuracy characteristics of TC intensity assessment depending on climate models and predicted future changes in TC intensity for each basin. The climate data used in t...
To improve its accuracy, we developed a system to assimilate the drifting buoy observations into the spectral wave model, WAVEWATCH III. We implemented Optimal Interpolation as data assimilation method. We conducted typhoon wave simulations in the Western North Pacific, targeting the typhoon waves in the summer of 2022. The accuracy of wave simulat...
Although tsunami inundation calculations for urban areas have been performed using high-resolution topography and taking buildings directly into account, it is important to use a calculation method that uses a resolution coarser than the width of the building from the viewpoint of computational load.
In this study, the model is improved by feeding...
Coastal cities are exposed to various types of disaster risks, such as tsunamis and storm surges. In particular, a megathrust earthquake has a potential to cause severe damage to cities almost simultaneously in terms of both seismic ground shaking and tsunami damage. However, in the countermeasures against future disasters, seismic and tsunami dama...
Impact assessments of climate change on coastal hazard risk are conducted in order to evaluate how coastal communities should adapt their coastal defense systems and other mitigation measures going forward. In this context, global mean sea level rise has been well-studied for several decades now. In addition, to mean sea level rise, it is important...
To evaluate the impacts of global warming on local‐scale extreme precipitation in Japan, 720‐year ensemble dynamical downscaling is conducted by a regional climate model with a 5 km grid spacing. Our dynamical downscaling is based on the large ensemble data set called the database for Policy Decision making for Future climate change (d4PDF). Compar...
Based on climate projections considering global warming, various impact assessments have been made for temperature, precipitation, water resources, and sea-level rise (e.g., IPCC AR6, 2021). In coastal areas, sea-level rise is mainly important as a gradual change in the coastal environment. At the same time, extreme events such as tropical cyclones...
Recently, coastal disaste have occurred by typhoons passing through bays, such as Typhoon Jebi in 2018 and Typhoon Hagibis in 2019 (Mori et al.(2019), Shimozono et al.(2020)). The current wave model cannot simultaneously account for the development of wind waves due to strong winds and wave deformation due to topography. This study aims to develop...
The recent IPCC report indicated that the ratio of strong tropical cyclones (TCs) can increase due to climate change, and there is concern that the intensified TCs would increase the risk of storm surges. However, a storm surge is an extreme event with a lower frequency compared to strong winds and heavy precipitation. Thus, it is difficult to esti...
Chile is one of the most seismic countries world wide with approximately 86.000 km of coastline and a permanent need for development and management. Because of the Nazca plate subducting the South American plate, coastal evolution is modeled by oceanographic variables and plate tectonics Coastal towns are under permanent tsunami and storm risks unr...
The 2022 Hunga Tonga-Hunga Ha’apai eruption generated tsunamis that propagated across the Pacific Ocean. Along the coast of Japan, nearshore amplification led to amplitudes of nearly 1 m at some locations, with varying peak tsunami occurrence times. The leading tsunami wave can generally be reproduced by Lamb waves, which are a type of air-pressure...
Tropical cyclone is one of the most destructive natural phenomena, causing tremendous disasters worldwide. The maximum intensity of tropical cyclones is determined by momentum and heat transfer at the air-sea interface. Momentum transfer corresponds to the momentum loss of tropical cyclones and, consequently, to the underlying ocean’s momentum gain...
The d4PDF-WaveHs dataset represents the first single model initial-condition large ensemble of historical significant ocean wave height (Hs) at a global scale. It was produced using an advanced statistical model with predictors derived from Japan’s d4PDF ensemble of historical simulations of sea level pressure. d4PDF-WaveHs provides 100 realization...
Historical trends in the direction and magnitude of ocean surface wave height, period, or direction are debated due to diverse data, time-periods, or methodologies. Using a consistent community-driven ensemble of global wave products, we quantify and establish regions with robust trends in global multivariate wave fields between 1980 and 2014. We f...
We analyzed tropical cyclones (TC) based on the theory of Maximum Potential Intensity (MPI) and Maximum Potential Surge (MPS) for a long-term assessment of extreme TC intensity and storm surge heights. We investigated future changes in the MPI fields and MPS for different global warming levels based on 150-year continuous scenario projections (High...
Tropical cyclones (TCs) cause severe coastal flooding in the middle latitudes. While the IPCC Fifth Assessment Reports (AR5, 2013) have focused on mean sea-level rise, recent advances (e.g., IPCC Sixth Assessment Reports, AR6, 2021) have shown the importance of storm surges and wave changes in extreme water levels causing coastal flooding. Both TC...
This study shows how the worst class of typhoons and related storm surge height along major bays in Japan will change based on MPI (Maximum Potential Intensity) theory and MPS (Maximum Potential Storm surge height) model. The climate data used in this study is HighResMIP (High-Resolution Model Intercomparison Project) experiment, which includes hig...
Global estimation of extreme sea levels is required for coast protection. First, 62-year-long historical total sea levels were calculated using an unstructured grid storm surge model and validated against tide gauge data all across the coastlines. Total sea levels were calculated by summing up astronomical tide and storm surge, which were derived s...
New climate experiment was proposed using a model that combines the Meteorological Research Institute's Atmospheric Global Circulation Model (MRI-AGCM) with a slab ocean model to evaluate the impact of warming on tropical cyclones. A month-fixed EA experiment was conducted under the present and future climate under ssp585 scenarios in the climate p...
The number of observations on extreme waves generated by typhoons in the open ocean has been limited. This study conducted the spatial observation of typhoon extreme waves in the open ocean including wave spectra by deploying small GPS-tracked ocean wave buoys recently developed and utilizing the satellite ocean wave data. The typhoon extreme waves...
The individual Drag Force Model (iDFM), a subgrid-scale model that treats groups of buildings in a grid as drag forces, is developed and coupled with the AMR method, in which the computational grid size is refined in time and space, to develop an efficient numerical model of storm surge inundation over metropolis including different scales phenomen...
We conducted a combined probability assessment of earthquake ground motion and tsunami damage for buildings in the entire city of Osaka, considering individual structure types. First, numerous finite fault models were synthetically generated along Nankai Trough. Each fault model has a different slip distribution with similar wavenumber characterist...
This study aims to identify the main factor of sea-level change around Japan. In order to consider climate change that occurs on various temporal and spatial scales, we analyzed three different types of the dataset; tide gauge observation around Japan, sea-level projection by the MIROC6 global climate model (100 km horizontal resolution), and ocean...
Wave response due to topography plays a dominant role in long wave behavior such as tsunamis. Understanding tsunami response functions in real bathymetry can lead to a better prediction of early warning system. This study estimated response functions of tsunamis due to bathymetry, targeting on the Pacific coast of Japan. The estimation method was ba...
Ocean surface wind and wave information is important in a wide variety of areas, such as coastal disaster reduction, offshore structure design, and atmosphere‐ocean flux estimation. This study proposed a new method for ocean surface wind estimation from surface wave spectrum information measured by small global positioning system buoys. The concept...
This study assesses the effects of internal climate variability on wave height trend assessment using the d4PDF-WaveHs, the first single model initial-condition large ensemble (100-member) of significant wave height (Hs) simulations for the 1951–2010 period, which was produced using sea level pressure taken from Japan’s d4PDF ensemble of historical...
Wave climate is a primary driver of coastal risk, yet how climate change is altering wave climate is not fully understood. Here we identify transitional wave climate regions, coastlines with a future change in the occurrence frequency of a wave climate, with most of the regions located in south-western and eastern ocean basins. Analysis of the spat...
Numerical tsunami inundation simulations using high-resolution (HR) topographical data are important to predict tsunami damage in urban areas at individual building levels accurately but are challenging due to the high computational cost. To address this issue, a subgrid-scale (SGS) model of tsunami inundation, called the individual drag force mode...
There are numerous global ocean wave reanalysis and hindcast products currently being distributed and used across different scientific fields. However, there is not a consistent dataset that can sample across all existing products based on a standardized framework. Here, we present and describe the first coordinated multi-product ensemble of presen...
Oceania comprises many Small Island Developing States (SIDS), the majority of which are founded on volcanic islands. Small islands are generally vulnerable to the effects of climate change. However, a high number of islands and different coastal morphology make it challenging to accurately estimate climate change impact on this region. Nevertheless...
For coastal adaptation purposes, it is important to estimate the climate related changes in extreme sea levels due to storm surges and ocean waves, in addition to mean sea level rise. This study provides the first consistent and continuous estimation of projected changes in global storm surges and ocean waves from the past to the warmer future, bas...
The parameterization of the sea surface turbulent kinetic energy (TKE) flux due to wave breaking was revisited using the observed data. It is found that the fraction of wave energy taken up into the ocean as sea surface TKE flux depends on the relative angle between wind and wave direction. The fraction tends to be larger under opposite wind condit...
Mangroves are able to attenuate tsunamis, storm surges, and waves. Their protective function against wave disasters is gaining increasing attention as a typical example of the green infrastructure/Eco-DRR (Ecosystem-based Disaster Risk Reduction) in coastal regions. Hydrodynamic models commonly employed additional friction or a drag forcing term to...
Hindcast experiments and pseudo-forecast experiments considering Typhoon Haishen (2020) were conducted using an atmospheric (WRF)-storm surge (GeoClaw) coupled model and a storm surge model with a parametric typhoon model. A series of simulations of the coupled model were used to quantify the error sources of the typhoon track and intensity in the...
The Pacific region consists of numerous Small Island Developing States (SIDS), one of the most vulnerable to flooding caused by compound effects of sea level rise (SLR) and storms. Nevertheless, individual studies regarding the impact assessment for SIDS, such as the low-lying Kiribati, remain scarce. This study assessed the impact of climate chang...
It is becoming important to consider the growth of wind waves due to strong typhoon winds in the bay. However, wave growth in the bay is an intermediate phenomenon hardly modeled by either spectral wave model or phase resolving wave model. Therefore, it is necessary to introduce wind stress terms in the phase resolving wave model that doesn’t usual...
In this study, we examined future changes of explosive cyclones around Japan and their effects on waves along the nation-wide coast using a seamless 150-year high-resolution climate projection from the present to the future climate under warming conditions. The climate projection showed that the number of intense explosive cyclones tends to increas...
The time series prediction of wave height is important for the countermeasure of high wave disaster in the coastal area. Since time series prediction of wave heights over a long recurrence period by dynamical methods is computationally expensive, statistical methods such as neural networks (NN) are considered for prediction. Among the deep learning...
This study conducts numerical tsunami simulations for future Nankai-Tonankai earthquakes and compares the tsunami amplitudes of different earthquake source catalogs along the coastal area of Japan. One of the catalogs is 11 source models proposed by the Central Disaster Management Council (CDMC), the Cabinet Office of Japan. The other is 300 source...
For climate adaptation planning for coastal area, understanding sea level rise on regional-scale is required. We have to assess not only changes in the global averaged sea level but also natural variability in local sea level. In this study, we conducted the analysis of dynamic sea level projection data from the global climate model (MIROC6) and re...
Turbulent mixing in ocean upper layer induces cooling of sea surface temperature (SST) and reductions of heat flux from ocean to typhoon. Sea surface turbulent kinetic energy (TKE) induced by wave dissipation is one of the main source of upper layer turbulence. In this study, two kinds of numerical experiments targeting typhoon Neoguri (2014) have...
Studies on the effects of climate change on waves and storm surges have been widely conducted. In comparison with storm surges, there is a lack of information on the future prediction of waves because of the high computational cost. One of the methods to reduce the computational cost is the statistical wave model. Wind speed and pressure are used a...
In this study, the effects of global warming on tropical cyclones (TCs) were evaluated by using a slab-ocean model coupled with the Atmospheric Global Climate Model (MRI-AGCM) . The warming conditions for the MRI-AGCM climate simulations were obtained from the latest climate models (CMIP6). We have conducted two types of global climate simulations,...
For coastal adaptation purposes, it is important to estimate climate change related future changes in extreme sea levels due to storm surge and ocean waves, in addition to sea level rise. In this study, global storm surge and ocean wave simulations forced by hourly surface winds and pressure from global climate model simulations were conducted. The...
This study proposes and projects the new framework for calculating the climatic Maximum Potential Storm surge height (MPS) based on the typhoon’s Maximum Potential Intensity (MPI) theory for Japan’s major 53 bays. The MPS is optimaized based on dynamic storm surge simulation and is estimate the characteristics of wind-surge for each bay. We analyze...
Understanding the systematic characteristics of tropical cyclones (TCs) represented in the Global Climate Model (GCM) is important for reliable climate change impact assessments. The atmospheric GCM (AGCM) and ocean wave models were coupled by incorporating the wave-dependent momentum flux. Systematic impacts of wave-dependent momentum flux on TC c...
We provide a comprehensive analysis of the spatial-temporal changes in the atmospheric-driven major wave climates (easterlies, southerlies, and westerlies) under two different Representative Concentration Pathways, the RCP2.6 and RCP8.5 scenarios for the end-of-the-century (2075–2099). By comparing the projected scenarios with historical conditions...
Extreme surface ocean waves are often primary drivers of coastal flooding and erosion over various time scales. Hence, understanding future changes in extreme wave events owing to global warming is of socio-economic and environmental significance. However, our current knowledge of potential changes in high-frequency (defined here as having return p...
This paper presents a multivariate classification of the global wave climate into types driven by atmospheric circulation patterns. The primary source of the net long-term variability is evaluated based on historical wave simulations. Results show that the monsoon, extratropical, subtropical, and polar wave climate types of the Pacific and North At...
Unmanned aerial vehicles (UAVs), represented by rotor-based drones, are suitable for volcanic observations owing to the advantages of mobility and safety. In this study, vertical profiles of wind and aerosol concentrations at altitudes up to 1000 m around Mt. Sakurajima, one of the most active volcanoes in Japan, were measured in situ using a drone...
This study developed an integrated model for the long-term assessment of extreme storm surge heights based on the maximum potential intensity (MPI) of a tropical cyclone, which is used to conduct future climatological projections of maximum potential storm surge height (MPS). We apply the MPS method to three major bays in Japan, Tokyo, Osaka, and N...
Climate change due to global warming is expected to have major impacts on phenomena such as tropical cyclones (TCs), Baiu, precipitation, and seasonal storms. Many natural disasters in East Asia are driven by TC (typhoon) activity in particular and their associated hazards are sensitive to local-scale characteristics. As such, it is critically impo...
A Correction to this paper has been published: https://doi.org/10.1007/s10584-021-03023-1
Issues related to climate change in coastal areas have been addressed in a wide variety of academic fields and societies, including meteorology, marine physics, chemistry, biology, ecology, policy science, and economics. However, the efforts and initiatives of each relevant academic field or society are rarely shared because climate change science...
The compounding effects of storm surges and sea level rise (SLR) are expected to accelerate coastal hazards and inundation. Therefore, projecting the compound effects in coastal territories is important for impact assessments and adaptation. Small island states in the South Pacific are one of the areas that are the most highly impacted by climate c...
Future projections of ocean wave climate related with global warming has been conducted for the assessment of climate change impacts on coastal disaster, beach morphology, and coastal structure design. In this study, we conduct the high-resolution future wave climate projection in the East Asia region and detail analysis on wave climate based on tw...
Projecting the sea level rise (SLR), storm surges, and related inundation in the Pacific Islands due to climate change is important for assessing the impact of climate change on coastal regions as well as the adaptation of the coastal regions. The compounding effects of storm surges and SLR are one of the major causes of flooding and extreme events...
Climatology of tropical cyclone (TC) intensity produced by global climate model (GCM) is important for climate change assessment. The available energy of a tropical cyclone is determined by the conditions of the environment around TC. Particularly, the sea surface temperature (SST) is an important factor in TC intensity. In this study, we have deve...