| 1. |
Watanabe, S., Y. Maruya, S. Yano, K. Nakayama, Perceptions of practitioners on the importance and achievement of research and social implementation activities on marine and freshwater carbon, Frontiers in Marine Science, doi:10.3389/fmars.2022.1036248, 9, 1036248, 2023.01. |
| 2. |
EXPLORING APPROPRIATE INFLATION AND LOCALIZATION METHODSTO STABILIZE ENSEMBLE DATA ASSIMILATIONOF A RAINFALL-RUNOFF-INUNDATION MODEL
Data assimilation can improve forecast accuracy of dynamical models by combining model state variables and real-world observations. This study applied the ensemble Kalman filter (EnKF) for a rainfall-runoff-inundation (RRI) model to adjust model state variables with operational water-level observations. In contrast to atmospheric models, model state errors do not propagate in the non-chaotic RRI model. Therefore, it is important to explore error inflation methods for providing appropriate background error covariance for the EnKF. For that purpose, this study perturbed rainfall intensity for ensemble members as a way of the covariance inflation.
A series of experiments with and without EnKF were employed in Omono River in Akita Prefecture. Our experiments showed that predicted water level was improved at both observed and unobserved stations compared to the RRI simulations without assimilation. This study also investigated effective localization methods for the RRI model. The application of localization along the river channel was found to perform as well as traditional localization based on Euclid distances commonly used in atmospheric data assimilation.. |
| 3. |
David Mason, Akiko Iida, Satoshi Watanabe, Luke P. Jackson, Makoto Yokohari, How urbanization enhanced exposure to climate risks in the Pacific: A case study in the Republic of Palau, ENVIRONMENTAL RESEARCH LETTERS, 10.1088/1748-9326/abb9dc, 15, 11, 2020.11, The increasing risk of coastal flooding and water shortage in Pacific Island Countries is usually attributed to climate change hazards. This ignores other risk components, exposure and vulnerability, of which a major contributor is urbanization.We develop simplified analyses that can be applied to other PICs. By dividing climate risks into hazard and exposure components we determine how urbanization contributed to present-day risks and then predict how growing climate change hazards may increase future risk, using the Republic of Palau as a case study.Results show that urbanization was responsible for 94% of the buildings exposed to coastal flooding today. Projected sea level rise, 30.2 cm by 2050, only increased exposure of today's buildings by 0.5%. In both present and future scenarios exposure resultant from urbanization was more significant than sea level rise.Our water scarcity index showed urbanization caused 3 of the 7 recorded water shortages from 1980-2018. From 2041-2079, analysis of projected rainfall showed mean reductions between 1.6-16.6% and increased variance between 0.3-3.4%. This led to three times as many water shortages under present population levels. In historical and future scenarios exposure from increased population was just as significant in causing water shortages as rainfall variation.These findings suggest that urban management is an important tool to lower exposure to coastal flooding and water shortage and we recommend that decision makers prioritize urbanization within climate risk policy in Pacific Island Countries.. |
| 4. |
Satoshi Watanabe, Shunji Kotsuki, Shinjiro Kanae, Kenji Tanaka, Atsushi Higuchi, Snow water scarcity induced by record-breaking warm winter in 2020 in Japan, SCIENTIFIC REPORTS, 10.1038/s41598-020-75440-8, 10, 1, 2020.10, This study highlights the severity of the low snow water equivalent (SWE) and remarkably high temperatures in 2020 in Japan, where reductions in SWE have significant impacts on society due to its importance for water resources. A continuous 60-year land surface simulation forced by reanalysis data revealed that the low SWE in many river basins in the southern snowy region of mainland Japan are the most severe on record. The impact of the remarkably high temperatures in 2020 on the low SWE was investigated by considering the relationships among SWE, temperature, and precipitation. The main difference between the 2020 case and prior periods of low SWE is the record-breaking high temperatures. Despite the fact that SWE was the lowest in 2020, precipitation was much higher than that in 2019, which was one of the lowest SWE on record pre-2020. The results indicate the possibility that even more serious low-SWE periods will be caused if lower precipitation and higher temperatures occur simultaneously.. |
| 5. |
Characteristics of the snow depth in 2020 and estimation of future changes based on the relationship between temperature and precipitation.. |
| 6. |
Tanoue, M, R. Taguchi, S. Nakata, S. Watanabe, S. Fujimori, Y.Hirabayashi, Estimation of direct and indirect economic losses caused by a flood with long-lasting inundation: Application to the 2011 Thailand flood, Water Resources Research, 2020.04. |
| 7. |
COMPARISON BETWEEN STATISTICAL CORRECTION METHOD AND DYNAMICAL DOWNSCALING FOR JRA-55 IN RIVER BASIN SCALE TOWARD CLIMATE CHANGE IMPACT ASSESSMENT. |
| 8. |
Watanabe, Megumi, Yanagawa, Aki, Watanabe, Satoshi, Hirabayashi, Yukiko, Kanae, Shinjiro, Quantifying the range of future glacier mass change projections caused by differences among observed past-climate datasets, CLIMATE DYNAMICS, 10.1007/s00382-019-04868-0, 53, 3-4, 2425-2435, 2019.08, Observed past climate data used as input in glacier models are expected to differ among datasets, particularly those for precipitation at high elevations. Differences among observed past climate datasets have not yet been described as a cause of uncertainty in projections of future changes in glacier mass, although uncertainty caused by varying future climate projections among general circulation models (GCMs) has often been discussed. Differences among observed past climate datasets are expected to propagate as uncertainty in future changes in glacier mass due to bias correction of GCMs and calibration of glacier models. We project ensemble future changes in the mass of glaciers in Asia through the year 2100 using a glacier model. A set of 18 combinations of inputs, including two observed past air temperature datasets, three observed past precipitation datasets, and future air temperature and precipitation projections from three GCMs were used. The uncertainty in projected changes in glacier mass was partitioned into three distinct sources: GCM uncertainty, observed past air temperature uncertainty, and observed past-precipitation uncertainty. Our findings indicate that, in addition to the differences in climate projections among GCMs, differences among observed past climate datasets propagate fractional uncertainties of about 15% into projected changes in glacier mass. The fractional uncertainty associated with observed past precipitation was 33-50% that of the observed air temperature. Differences in observed past air temperatures and precipitation did not propagate equally into the ultimate uncertainty of glacier mass projection when ablation was dominant.. |
| 9. |
Efficiency and sustainability of land-resource use on a small island. |
| 10. |
UNCERTAINTY FROM CLIMATE FORCING OF PROJECTIONS IN GLACIER MELT FOR HIGH MOUNTAIN ASIA. |
| 11. |
The development of bias corrected hourly precipitation dataset for AMeDAS stations based on the projections from d4PDF. |
| 12. |
ESTIMATION OF FLOOD DAMAGE UNDER CLIMATE CHANGE WITH CONSIDERING DEPOPULATION AND ASSET DISTRIBUTION CHANGE. |
| 13. |
Classifying large ensemble database of future climate projection : A case of precipitation in Japan. |
| 14. |
Projection of the changes in weather Potentially affecting tourism in the Yaeyama islands under global warming. |
| 15. |
Daisuke Komori, Prem Rangsiwanichpong, Naotatsu Inoue, Keisuke Ono, Satoshi Watanabe, So Kazama, Distributed probability of slope failure in Thailand under climate change, Climate Risk Management, 10.1016/j.crm.2018.03.002, 20, 126-137, 2018.01, Landslides are more widespread compared to any other geological hazards in Thailand. The steep slope and high elevation areas have more potential for landslide hazards. However, weather extremes, particularly extreme rainfall, play a major role in the occurrence of landslides in Thailand. The objective of the present study is to analyze the changes in the probability of landslide occurrences in Thailand due to climate change. For this purpose, probabilistic landslide hazard maps for extreme rainfall values for 5-, 10-, 50-, and 100-year return periods are developed for historical and future climatic conditions, derived from 10 global climate models (GCMs) under two representative concentration pathway (RCP) scenarios, namely, RCP 4.5 and RCP 8.5. The results reveal that the 5-year return period extreme rainfall amount will reach 200 mm/month in the eastern and southern provinces for RCP 4.5 and the northwestern, eastern, and southern provinces for RCP 8.5. The increase in extreme rainfall will cause a sharp increase in the landslide probability in Thailand, except in low altitude regions. The probability of 100-year return period landslide will increase by 90% in 40% and 80% of the areas in Thailand under RCP 4.5 and RCP 8.5, respectively. It is expected that the landslide hazard maps developed in this study will help policy makers take necessary measures to mitigate increasing landslide events due to climate change.. |
| 16. |
Youhei Kinoshita, Masahiro Tanoue, Satoshi Watanabe, Yukiko Hirabayashi, Quantifying the effect of autonomous adaptation to global river flood projections: Application to future flood risk assessments, Environmental Research Letters, 10.1088/1748-9326/aa9401, 13, 1, 2018.01, This study represents the first attempt to quantify the effects of autonomous adaptation on the projection of global flood hazards and to assess future flood risk by including this effect. A vulnerability scenario, which varies according to the autonomous adaptation effect for conventional disaster mitigation efforts, was developed based on historical vulnerability values derived from flood damage records and a river inundation simulation. Coupled with general circulation model outputs and future socioeconomic scenarios, potential future flood fatalities and economic loss were estimated. By including the effect of autonomous adaptation, our multimodel ensemble estimates projected a 2.0% decrease in potential flood fatalities and an 821% increase in potential economic losses by 2100 under the highest emission scenario together with a large population increase. Vulnerability changes reduced potential flood consequences by 64%-72% in terms of potential fatalities and 28%-42% in terms of potential economic losses by 2100. Although socioeconomic changes made the greatest contribution to the potential increased consequences of future floods, about a half of the increase of potential economic losses was mitigated by autonomous adaptation. There is a clear and positive relationship between the global temperature increase from the pre-industrial level and the estimated mean potential flood economic loss, while there is a negative relationship with potential fatalities due to the autonomous adaptation effect. A bootstrapping analysis suggests a significant increase in potential flood fatalities (+5.7%) without any adaptation if the temperature increases by 1.5°C-2.0°C, whereas the increase in potential economic loss (+0.9%) was not significant. Our method enables the effects of autonomous adaptation and additional adaptation efforts on climate-induced hazards to be distinguished, which would be essential for the accurate estimation of the cost of adaptation to climate change.. |
| 17. |
CONSIDERATIONS ON THE USE OF QUANTILE MAPPING BIAS CORRECTION FOR THE IMPACT ASSESSMENT OF CLIMATE CHANGE. |
| 18. |
STATISTICAL CORRECTION METHOD FOR PRECIPITATION OF JRA-55 IN LOCAL SCALE TOWARD CLIMATE CHANGE IMPACT ASSESSMENT. |
| 19. |
Yukiko Hirabayashi, Kazunari Nakano, Yong Zhang, Satoshi Watanabe, Masahiro Tanoue, Shinjiro Kanae, Contributions of natural and anthropogenic radiative forcing to mass loss of Northern Hemisphere mountain glaciers and quantifying their uncertainties, SCIENTIFIC REPORTS, 10.1038/srep29723, 6, 2016.07, Observational evidence indicates that a number of glaciers have lost mass in the past. Given that glaciers are highly impacted by the surrounding climate, human-influenced global warming may be partly responsible for mass loss. However, previous research studies have been limited to analyzing the past several decades, and it remains unclear whether past glacier mass losses are within the range of natural internal climate variability. Here, we apply an optimal fingerprinting technique to observed and reconstructed mass losses as well as multi-model general circulation model (GCM) simulations of mountain glacier mass to detect and attribute past glacier mass changes. An 8,800-year control simulation of glaciers enabled us to evaluate detectability. The results indicate that human-induced increases in greenhouse gases have contributed to the decreased area-weighted average masses of 85 analyzed glaciers. The effect was larger than the mass increase caused by natural forcing, although the contributions of natural and anthropogenic forcing to decreases in mass varied at the local scale. We also showed that the detection of anthropogenic or natural influences could not be fully attributed when natural internal climate variability was taken into account.. |
| 20. |
パラオ共和国バベルダオブ島における土地資源利用効率の検討. |
| 21. |
Hiroaki Ikeuchi, Michio Murakami, Satoshi Watanabe, Scavenging of PM2.5 by precipitation and the effects of precipitation pattern changes on health risks related to PM2.5 in Tokyo, Japan, WATER SCIENCE AND TECHNOLOGY, 10.2166/wst.2015.346, 72, 8, 1319-1326, 2015.10, Fine particulate matter (aerodynamic diameter |
| 22. |
GLOBAL WATER RESOURCE ASSESSMENT INCLUDING GLACIER MELTWATER FROM MOUNTAINOUS REGIONS. |
| 23. |
WATANABE Satoshi, HIRABAYASHI Yukiko, KOTSUKI Shunji, HANASAKI Naota, TANAKA Kenji, MATEO Cherry May R, KIGUCHI Masashi, IKOMA Eiji, KANAE Shinjiro, OKI Taikan, Application of performance metrics to climate models for projecting future river discharge in the Chao Phraya River basin, Hydrol Res Lett (Web), 10.3178/hrl.8.33, 8, 1, 33-38 (J-STAGE)-38, 2014.01. |
| 24. |
Kotsuki Shunji, Tanaka Kenji, Watanabe Satoshi, Projected hydrological changes and their consistency under future climate in the Chao Phraya River Basin using multi-model and multi-scenario of CMIP5 dataset, Hydrological Research Letters, 10.3178/hrl.8.27, 8, 1, 27-32, 2014.01, It is important to examine what future hydrological changes could occur as a result of climate change. In this study, we projected hydrological changes and their consistency under near-future and end-of-21st-century climate in the Chao Phraya River Basin. Through hydrological simulations using output from six AOGCMs under the RCP 4.5 and 8.5 scenarios, we have reached the following conclusions. Our results demonstrate a projected increase in mid-rainy season precipitation under future climate, which is a necessary condition for a large volume of runoff to occur in the late rainy season. Under end-of-21st-century climate, all simulations using six AOGCMs showed a large increase (> 20%) in runoff in Nakhon Sawan catchment under both RCP scenarios. Compared to the capacities of the Bhumibol and Sirikit dams, projected increases in runoff at the end of the 21st century are high. New flood management and mitigation plans will likely be necessary. Ensemble mean increases in precipitation and runoff were higher under RCP 8.5 than under the RCP 4.5 scenario in both projected periods. Thus, higher global mean temperature would cause higher precipitation and runoff in the basin. This inference is also supported by the higher precipitation and runoff projected under the late future compared with under the near-future climate.
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| 25. |
Caucasus地域におけるASTER衛星画像を用いたデブリ広域被覆分布の推定. |
| 26. |
Yukiko Hirabayashi, Roobavannan Mahendran, Sujan Koirala, Lisako Konoshima, Dai Yamazaki, Satoshi Watanabe, Hyungjun Kim, Shinjiro Kanae, Global flood risk under climate change, NATURE CLIMATE CHANGE, 10.1038/NCLIMATE1911, 3, 9, 816-821, 2013.09, A warmer climate would increase the risk of floods(1). So far, only a few studies(2,3) have projected changes in floods on a global scale. None of these studies relied on multiple climate models. A few global studies(4,5) have started to estimate the exposure to flooding (population in potential inundation areas) as a proxy of risk, but none of them has estimated it in a warmer future climate. Here we present global flood risk for the end of this century based on the outputs of 11 climate models. A state-of-the-art global river routing model with an inundation scheme(6) was employed to compute river discharge and inundation area. An ensemble of projections under a new high-concentration scenario(7) demonstrates a large increase in flood frequency in Southeast Asia, Peninsular India, eastern Africa and the northern half of the Andes, with small uncertainty in the direction of change. In certain areas of the world, however, flood frequency is projected to decrease. Another larger ensemble of projections under four new concentration scenarios(7) reveals that the global exposure to floods would increase depending on the degree of warming, but interannual variability of the exposure may imply the necessity of adaptation before significant warming.. |
| 27. |
A STUDY ON THE DIFFERENCE OF THE FUTURE ESTIMATES FOR DAILY EXTREME PRECIPITATION CAUSED BY THE SELECTION OF GCM, RCP EMISSION SCENARIO AND BIAS CORRECTION METHOD. |
| 28. |
Hirabayashi Yukiko, Zang Yong, Watanabe Satoshi, Koirala Sujan, Kanae Shinjiro, Projection of glacier mass changes under a high-emission climate scenario using the global glacier model HYOGA2, Hydrological Research Letters, 10.3178/hrl.7.6, 7, 1, 6-11, 2013.02, We report a time series (1948–2100) of global-scale meltwater from mountain glaciers and ice caps (MGI) estimated by the global glacier model HYOGA2. HYOGA2 calculates the temporal fluctuation of the mass balance for 24,234 individual glaciers worldwide. It covers 90% of the total glacier area, except for glaciers in Greenland and Antarctica. HYOGA2 also accounts for regionally distributed changes in glacier area and altitude associated with glacier retreat and advance. By computation of individual glacier changes, future dissipation and glacier mass and area changes can be simulated in the model. The cumulative volume loss of water between 1948 and 2005 was estimated to be 25.9 ± 1.4 mm sea level equivalent (SLE). A future projection under a high-emission scenario demonstrated significant losses of water from MGI equivalent to 60.3 ± 7.9 mm SLE between 1948 and 2060 and 99.0 ± 14.9 mm SLE between 1948 and 2099.
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| 29. |
Satoshi Watanabe, Shinjiro Kanae, Shinta Seto, Pat J. -F. Yeh, Yukiko Hirabayashi, Taikan Oki, Intercomparison of bias-correction methods for monthly temperature and precipitation simulated by multiple climate models, JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 10.1029/2012JD018192, 117, 23, 2012.12, Bias-correction methods applied to monthly temperature and precipitation data simulated by multiple General Circulation Models (GCMs) are evaluated in this study. Although various methods have been proposed recently, an intercomparison among them using multiple GCM simulations has seldom been reported. Moreover, no previous methods have addressed the issue how to adequately deal with the changes of the statistics of bias-corrected variables from the historical to future simulations. In this study, a new method which conserves the changes of mean and standard deviation of the uncorrected model simulation data is proposed, and then five previous bias-correction methods as well as the proposed new method are intercompared by applying them to monthly temperature and precipitation data simulated from 12 GCMs in the Coupled Model Intercomparison Project (CMIP3) archives. Parameters of each method are calibrated by using 1948-1972 observed data and validated in the 1974-1998 period. These methods are then applied to the GCM future simulations (2073-2097) and the bias-corrected data are intercompared. For the historical simulations, negligible difference can be found between observed and bias-corrected data. However, the differences in future simulations are large dependent on the characteristics of each method. The new method successfully conserves the changes in the mean, standard deviation and the coefficient of variation before and after bias-correction. The differences of bias-corrected data among methods are discussed according to their respective characteristics. Importantly, this study classifies available correction methods into two distinct categories, and articulates important features for each of them. Citation: Watanabe, S., S. Kanae, S. Seto, P. J.-F. Yeh, Y. Hirabayashi, and T. Oki (2012), Intercomparison of bias-correction methods for monthly temperature and precipitation simulated by multiple climate models, J. Geophys. Res., 117, D23114, doi:10.1029/2012JD018192.. |
| 30. |
平成23年7月新潟・福島豪雨による信濃川下流域での出水と被害の特徴―平成16年7月新潟・福島豪雨との比較を中心として―. |
| 31. |
GCM出力値補正手法により生じる月平均気温および月降水量の予測差. |
| 32. |
Satoshi Watanabe, Daisuke Komori, Masatoshi Aoki, Wonsik Kim, Samakkee Boonyawat, Piyapong Tongdeenok, Saman Prakarnrat, Somchai Baimoung, Estimation of Daily Solar Radiation from Sunshine Duration in Thailand, JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN, 10.2151/jmsj.2011-A25, 89A, 355-364, 2011.02, The empirical relationship between solar radiation and sunshine duration in Thailand is studied in this paper. Although regional long-term regional solar radiation has not yet been measured in Thailand, the data of sunshine duration measurements are available. Hence, measurement of global solar radiation is conducted to find the relationship between daily solar radiation and sunshine duration, which is mostly linear. The distribution of regression coefficients is examined and the formula that can be applied in Thailand is estimated. The efficiency of the proposed formula is validated through its prediction. The result shows that the accuracy of the country-wide regression equations can be comparable to that constructed at each station. Moreover, it is found that the proposed equations are more effective from May to November than from December to April. The proposed equations are applied to estimate solar radiation in Thailand and the differences in their prediction are found in the characteristics of statistical distributions between May November and December April.. |
| 33. |
GCM月降水量補正手法およびMIROC5出力補正値の考察. |
| 34. |
平成21年8月台風9号に伴う豪雨による水害の特徴. |
| 35. |
気候変動下での全球水資源量評価に向けた気候モデル出力値補正手法の開発と検証. |
