Authorship：Lead author  

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DOI： 10.34467/jssoilphysics.151.0_27

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Copernicus GmbH  

Abstract. The Nonhydrostatic ICosahedral Atmospheric Model
(NICAM), a global model with an icosahedral grid system, has been under
development for nearly two decades. This paper describes NICAM16-S, the
latest stable version of NICAM (NICAM.16), modified for the Coupled Model
Intercomparison Project Phase 6, High Resolution Model Intercomparison
Project (HighResMIP). Major updates of NICAM.12, a previous version used
for climate simulations, included updates of the cloud microphysics scheme
and land surface model, introduction of natural and anthropogenic aerosols
and a subgrid-scale orographic gravity wave drag scheme, and improvement of
the coupling between the cloud microphysics and the radiation schemes.
External forcings were updated to follow the protocol of the HighResMIP. A
series of short-term sensitivity experiments were performed to determine and
understand the impacts of these various model updates on the simulated mean
states. The NICAM16-S simulations demonstrated improvements in the ice water
content, high cloud amount, surface air temperature over the Arctic region,
location and strength of zonal mean subtropical jet, and shortwave radiation
over Africa and South Asia. Some long-standing biases, such as the double
intertropical convergence zone and smaller low cloud amount, still exist or
are even worse in some cases, suggesting further necessity for understanding
their mechanisms, upgrading schemes and parameter settings, and
enhancing horizontal and vertical resolutions.

DOI： 10.5194/gmd-14-795-2021

Scopus

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Meteorological Society  

<title>Capsule</title>
The latest snow model intercomparison identified the same modelling issues as previous iterations over 23 years. Lack of new insights are attributed partly to human errors and intercomparison projects design.

DOI： 10.1175/bams-d-19-0329.1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Hydrology and Water Resources  

DOI： 10.3178/hrl.15.98

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DOI： 10.2208/jscejhe.77.2_I_229

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Copernicus GmbH  

The 30-year simulations of seasonal snow cover in 22 physically based models driven with bias-corrected meteorological reanalyses are examined at four sites with long records of snow observations. Annual snow cover durations differ widely between models, but interannual variations are strongly correlated because of the common driving data. No significant trends are observed in starting dates for seasonal snow cover, but there are significant trends towards snow cover ending earlier at two of the sites in observations and most of the models. A simplified model with just two parameters controlling solar radiation and sensible heat contributions to snowmelt spans the ranges of snow cover durations and trends. This model predicts that sites where snow persists beyond annual peaks in solar radiation and air temperature will experience rapid decreases in snow cover duration with warming as snow begins to melt earlier and at times of year with more energy available for melting.

DOI： 10.5194/tc-14-4687-2020

Scopus

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

<title>Abstract</title>
Accurate simulations of land processes are crucial for many purposes, such as climate simulation, weather, flood, and drought prediction, and climate change impact assessment studies. In this paper, we present a new land simulator called the Integrated Land Simulator (ILS). The ILS consists of multiple models that represent processes related to land (hereafter, referred to as “land models”). They are coupled by a general-purpose coupler, Jcup, and executed using the Multiple Program Multiple Data approach. Currently, ILS includes a physical land surface model, the Minimal Advanced Treatments of Surface Interaction and Runoff model, and a hydrodynamic model, the Catchment-based Macro-scale Floodplain model, and the inclusion of additional land models is planned. We conducted several test simulations to evaluate the computational speed and scalability and the basic physical performance of the ILS. The results will become a benchmark for further development.

DOI： 10.1186/s40645-020-00383-7

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Other Link： http://link.springer.com/article/10.1186/s40645-020-00383-7/fulltext.html

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

<title>Abstract</title>To date, the treatment of permafrost in global climate models has been simplified due to the prevailing uncertainties in the processes involving frozen ground. In this study, we improved the modeling of permafrost processes in a state-of-the-art climate model by taking into account some of the relevant physical properties of soil such as changes in the thermophysical properties due to soil freezing. As a result, the improved version of the global land surface model was able to reproduce a more realistic permafrost distribution at the southern limit of the permafrost area by increasing the freezing of soil moisture in winter. The improved modeling of permafrost processes also had a significant effect on future projections. Using the conventional formulation, the predicted cumulative reduction of the permafrost area by year 2100 was approximately 60% (40–80% range of uncertainty from a multi-model ensemble) in the RCP8.5 scenario, while with the improved formulation, the reduction was approximately 35% (20–50%). Our results indicate that the improved treatment of permafrost processes in global climate models is important to ensuring more reliable future projections.

DOI： 10.1186/s40645-020-00380-w

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Other Link： http://link.springer.com/article/10.1186/s40645-020-00380-w/fulltext.html

Language：English   Publishing type：Research paper (scientific journal)   Publisher：COPERNICUS GESELLSCHAFT MBH  

Future changes in the climate system could have significant impacts on the natural environment and human activities, which in turn affect changes in the climate system. In the interaction between natural and human systems under climate change conditions, land use is one of the elements that play an essential role. On the one hand, future climate change will affect the availability of water and food, which may impact land-use change. On the other hand, human-induced land-use change can affect the climate system through biogeophysical and biogeochemical effects. To investigate these interrelationships, we developed MIROC-INTEG-LAND (MIROC INTEGrated LAND surface model version 1), an integrated model that combines the land surface component of global climate model MIROC (Model for Interdisciplinary Research on Climate) with water resources, crop production, land ecosystem, and land-use models. The most significant feature of MIROC-INTEG-LAND is that the land surface model that describes the processes of the energy and water balance, human water management, and crop growth incorporates a land use decision-making model based on economic activities. In MIROC-INTEG-LAND, spatially detailed information regarding water resources and crop yields is reflected in the prediction of future land-use change, which cannot be considered in the conventional integrated assessment models. In this paper, we introduce the details and interconnections of the submodels of MIROC-INTEG-LAND, compare historical simulations with observations, and identify various interactions between the submodels. By evaluating the historical simulation, we have confirmed that the model reproduces the observed states well. The future simulations indicate that changes in climate have significant impacts on crop yields, land use, and irrigation water demand. The newly developed MIROC-INTEG-LAND could be combined with atmospheric and ocean models to develop an integrated earth system model to simulate the interactions among coupled natural-human earth system components.

DOI： 10.5194/gmd-13-4713-2020

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

This study presents the results of the ERTDF S-12 project for searching an optimum reduction scenario of the short-lived climate pollutants (SLCPs) to simultaneously mitigate the global warming and environmental problems. The study utilized REAS emission inventory, Asia-Pacific Integrated Model-Enduse (AIM/Enduse), MIROC6 climate model, NICAM non-hydrostatic atmospheric model, and models for estimating environmental damages to health, agriculture, and flood risks. Results of various scenario search indicate that it is difficult to attain simultaneous reduction of global warming and environmental damages, unless a significant reduction of CO2 is combined with carefully designed SLCP reductions for CH4, SO2, black carbon (BC), NOx, CO, and VOCs. In this scenario design, it is important to take into account the impact of small BC reduction to the surface air temperature and complex atmospheric chemical interactions such as negative feedback between CH4 and NOx reduction. We identified two scenarios, i.e., B2a and B1c scenarios which combine the 2D-scenario with SLCP mitigation measures using End-of-Pipe (EoP) and new mitigation technologies, as promising to simultaneously mitigate the temperature rise by about 0.33 degrees C by 2050 and air pollution in most of the globe for reducing damages in health, agriculture, and flood risk. In Asia and other heavy air pollution areas, health-care measures have to be enhanced in order to suppress the mortality increase due to high temperature in hot spot areas caused by a significant cut of particulate matter. For this situation, the B1b scenario is better to reduce hot spot areas and high-temperature damage to the public health.

DOI： 10.1186/s40645-020-00351-1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：COPERNICUS GESELLSCHAFT MBH  

The sixth version of the Model for Interdisciplinary Research on Climate (MIROC), called MIROC6, was cooperatively developed by a Japanese modeling community. In the present paper, simulated mean climate, internal climate variability, and climate sensitivity in MIROC6 are evaluated and briefly summarized in comparison with the previous version of our climate model (MIROC5) and observations. The results show that the overall reproducibility of mean climate and internal climate variability in MIROC6 is better than that in MIROC5. The tropical climate systems (e.g., summertime precipitation in the western Pacific and the eastward-propagating Madden-Julian oscillation) and the midlatitude atmospheric circulation (e.g., the westerlies, the polar night jet, and troposphere-stratosphere interactions) are significantly improved in MIROC6. These improvements can be attributed to the newly implemented parameterization for shallow convective processes and to the inclusion of the stratosphere. While there are significant differences in climates and variabilities between the two models, the effective climate sensitivity of 2.6K remains the same because the differences in radiative forcing and climate feedback tend to offset each other. With an aim towards contributing to the sixth phase of the Coupled Model Intercomparison Project, designated simulations tackling a wide range of climate science issues, as well as seasonal to decadal climate predictions and future climate projections, are currently ongoing using MIROC6.

DOI： 10.5194/gmd-12-2727-2019

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：COPERNICUS GESELLSCHAFT MBH  

This paper describes ESM-SnowMIP, an international coordinated modelling effort to evaluate current snow schemes, including snow schemes that are included in Earth system models, in a wide variety of settings against local and global observations. The project aims to identify crucial processes and characteristics that need to be improved in snow models in the context of local-and global-scale modelling. A further objective of ESM-SnowMIP is to better quantify snow-related feedbacks in the Earth system. Although it is not part of the sixth phase of the Coupled Model Intercomparison Project (CMIP6), ESM-SnowMIP is tightly linked to the CMIP6-endorsed Land Surface, Snow and Soil Moisture Model Intercomparison (LS3MIP).

DOI： 10.5194/gmd-11-5027-2018

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Language：Japanese  

CiNii Books

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER GEOPHYSICAL UNION  

The impacts of land use have been shown to have considerable influence on regional climate. With the recent international commitment to limit global warming to well below 2 degrees C, emission reductions need to be ambitious and could involve major land-use change (LUC). Land-based mitigation efforts to curb emissions growth include increasing terrestrial carbon sequestration through reforestation, or the adoption of bioenergy crops. These activities influence local climate through biogeophysical feedbacks, however, it is uncertain how important they are for a 1.5 degrees climate target. This was the motivation for HAPPI-Land: the half a degree additional warming, prognosis, and projected impactsland-use scenario experiment. Using four Earth system models, we present the first multimodel results from HAPPI-Land and demonstrate the critical role of land use for understanding the characteristics of regional climate extremes in low-emission scenarios. In particular, our results show that changes in temperature extremes due to LUC are comparable in magnitude to changes arising from half a degree of global warming. We also demonstrate that LUC contributes to more than 20% of the change in temperature extremes for large land areas concentrated over the Northern Hemisphere. However, we also identify sources of uncertainty that influence the multimodel consensus of our results including how LUC is implemented and the corresponding biogeophysical feedbacks that perturb climate. Therefore, our results highlight the urgent need to resolve the challenges in implementing LUC across models to quantify the impacts and consider how LUC contributes to regional changes in extremes associated with sustainable development pathways.Plain Language Summary The motivation for the Intergovernmental Panel on Climate Change Special Report of 1.5 degrees C stems from the need to understand how the impacts of climate change may evolve for half a degree of global warming. Most low-emission scenarios involve substantial land-use change (LUC) including the expansion of bioenergy and food crops, as well as afforestation. Future emission scenarios used as input to climate models are derived using integrated assessment models, and focus on greenhouse gas emissions. However, changes in land use also have a direct effect on local climate through the local water and energy balances, which is not considered in these models, and therefore, our understanding on how dependent these climate projections are to the choice of land-use scenario is limited. Our study demonstrates that the land-use scenario has a considerable influence on the projections of temperature extremes for low-emission scenarios. In particular, for large land areas in the Northern Hemisphere, more than 20% of the change in temperature extremes can be attributed to LUC. However, our study also reveals that considerable uncertainty remains on what the feedbacks of land use may mean for land-based mitigation activities.

DOI： 10.1002/2017EF000744

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;In this study, we investigated the impact of black carbon, BC, as one of Short-Lived Climate Pollutants or SLCP on terrestrial water circulation, in addition to that of sulfur dioxide, SO₂, with the terrestrial offline simulation framework. Results are shown as follows: 1) Both BC and SO₂ decrease the global precipitation whereas decrease in runoff is relatively large with BC. 2) However, spatial distributions of the change in precipitation and runoff are quite patchy and different in BC and SO₂. 3) Decrease in BC emission would relax the global water stress. 4) No matter decrease or increase, change in BC or SO₂ emission would cuase increase the risk of severe flood exposure.

DOI： 10.2208/jscejhe.74.I_217

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

<p> LS3MIP (The Land Surface, Snow and Soil moisuture Model Intercomparison Project) has been approved as Coupled Model Intercomparison Project Phase 6 (CMIP6) endorsed MIP to investigate climate forcing and land feedback. Land modeling groups of international community are preparing their model experiments under CMIP6 corrdination. In this study, we describe the overview of the model experiment design of LS3MIP. Also, we introduce the results from our test drive using MATSIRO for checking whether the experiment configuration accords with the protocol. The results show that inter-annual trends of runoff, snow cover fraction, soil moisture and evapotranspiration in global scale are reproduced observational variability properly. Results suggest that water balance tend to decrease around Himalaya Mountains in the 20th century. This is probably due to negative trend of precipitation in the region.</p>

DOI： 10.2208/jscejhe.74.5_I_43

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER METEOROLOGICAL SOC  

Wetlands cover large areas of the middle and high latitudes and influence the surface water and energy budget, surface hydrology, and the climate system. In this study, a scheme implicitly representing a snow-fed wetland, in which snowmelt can be stored with consideration of subgrid terrain complexity, was implemented in the Minimal Advanced Treatments of Surface Interaction and Runoff (MATSIRO) land surface model. An atmospheric general circulation model (AGCM) experiment was conducted using the Model for Interdisciplinary Research on Climate, version 5 (MIROC5), with and without the wetland scheme, with the main aim of reducing the model bias of warm and dry boreal summer at mid-to high latitudes. The experiment showed not only a better surface hydrology but also a weaker land-atmosphere coupling strength and larger (smaller) latent (sensible) heat flux due to the delayed snowmelt runoff. The summer warm and dry bias was partially improved over snowy and flat areas, particularly over much of western Eurasia and North America, without an apparent deterioration of simulated surface hydrology and climate over the rest of the land in the other seasons; the mean absolute error of 2-m air temperature and precipitation over land at 458-908N in summer decreased by 19% and 4%, respectively. The next step of model development will involve implementing an explicit representation of subgrid-scale surface water and related processes.

DOI： 10.1175/JHM-D-16-0105.1

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;1km-resolution terrestrial model over Japan is developped to build a high quality river discharge forecasting system. Effects of model resolution and soil type dataset are investigated by a sensitivity experiment concerning resolution and soil type dataset. The experiment period is 2 years of 2014, 2015 and analysis is conducted for 6 river basins in Japan. The terrestrial model is consists of MATSIRO, a land surface model and CaMa-Flood, a river routing model. Peak discharge and low discharge representation are improved by using a more detailed soil type dataset. In 9 of 12 experiments, ratios of model discharge to observation are improved by 1-14% and in all experiments, RMSE are decreased . Also, using high resolution experiment settings showed lower RMSE in 10 of 12 experiments.

DOI： 10.2208/jscejer.73.I_71

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：COPERNICUS GESELLSCHAFT MBH  

As part of the terrestrial branch of the Japan-funded Arctic Climate Change Research Project (GRENE-TEA), which aims to clarify the role and function of the terrestrial Arctic in the climate system and assess the influence of its changes on a global scale, this model intercomparison project (GTMIP) is designed to (1) enhance communication and understanding between the modelling and field scientists and (2) assess the uncertainty and variations stemming from variability in model implementation/design and in model outputs using climatic and historical conditions in the Arctic terrestrial regions. This paper provides an overview of all GTMIP activity, and the experiment protocol of Stage 1, which is site simulations driven by statistically fitted data created using the GRENE-TEA site observations for the last 3 decades. The target metrics for the model evaluation cover key processes in both physics and biogeochemistry, including energy budgets, snow, permafrost, phenology, and carbon budgets. Exemplary results for distributions of four metrics (annual mean latent heat flux, annual maximum snow depth, gross primary production, and net ecosystem production) and for seasonal transitions are provided to give an outlook of the planned analysis that will delineate the inter-dependence among the key processes and provide clues for improving model performance.

DOI： 10.5194/gmd-8-2841-2015

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Authorship：Lead author   Language：Japanese   Publisher：Japan Society of Civil Engineers  

Many lakes and wetlands exist in the Arctic. Their storage effects have the potential to improve the surface hydrology simulation and to decrease the surface air temperature bias. There are, however, only few global land surface models that incorporate wetlands and the effects upon climate are not yet well investigated. In the present study, we examine these effects through sensitivity experiments using MATSIRO land surface model with a simple wetland scheme that stores part of snowmelt. First, we conduct offline global land simulations and evaluate the results using multiple observations. The result shows that the river discharge simulation in the major Arctic river basins and the underestimation of evapotranspiration are improved. Further, we conduct a series of on-line AGCM experiments using MIROC5 with climatological monthly SST and sea ice boundary conditions. The result shows that the impact of wetland scheme upon the reduction of near surface air temperature in summer is significant.

DOI： 10.2208/jscejhe.71.I_955

CiNii Books

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER METEOROLOGICAL SOC  

Subgrid snow cover is one of the key parameters in global land models since snow cover has large impacts on the surface energy and moisture budgets, and hence the surface temperature. In this study, the Subgrid Snow Distribution (SSNOWD) snow cover parameterization was incorporated into the Minimal Advanced Treatments of Surface Interaction and Runoff (MATSIRO) land surface model. SSNOWD assumes that the subgrid snow water equivalent (SWE) distribution follows a lognormal distribution function, and its parameters are physically derived from geoclimatic information. Two 29-yr global offline simulations, with and without SSNOWD, were performed while forced with the Japanese 25-yr Reanalysis (JRA-25) dataset combined with an observed precipitation dataset. The simulated spatial patterns of mean monthly snow cover fraction were compared with satellite-based Moderate Resolution Imaging Spectroradiometer (MODIS) observations. The snow cover fraction was improved by the inclusion of SSNOWD, particularly for the accumulation season and/or regions with relatively small amounts of snowfall; snow cover fraction was typically underestimated in the simulation without SSNOWD. In the Northern Hemisphere, the daily snow-covered area was validated using Interactive Multisensor Snow and Ice Mapping System (IMS) snow analysis datasets. In the simulation with SSNOWD, snow-covered area largely agreed with the IMS snow analysis and the seasonal cycle in the Northern Hemisphere was improved. This was because SSNOWD formulates the snow cover fraction differently for the accumulation season and ablation season, and represents the hysteresis of the snow cover fraction between different seasons. The effects of including SSNOWD on hydrological properties and snow mass were also examined.

DOI： 10.1175/JCLI-D-13-00310.1

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Authorship：Lead author   Language：Japanese   Publisher：Japan Society of Civil Engineers  

Global- and continental-scale snow simulation has been used to produce snow estimates and attribute the change of snow into hydrological variables. However, uncertainties in global- and continental-scale snow simulation due to model structure, model parameters, and meteorological forcing has not been well documented. In the present study, we used MATSIRO land surface model and conducted ensemble simulations for snow, i.e., perturbed parameter ensemble simulation and multi precipitation ensemble simulation. The results show that uncertainties in parameters are larger in the melting season than accumulation season and uncertainties in precipitation are large in accumulation seasons. The uncertainties of parameters in melting season are comparable to that of precipitation.

DOI： 10.2208/jscejhe.69.I_439

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Authorship：Lead author   Language：Japanese   Publisher：Japan Society of Civil Engineers  

We incorporate a subgrid snow cover parameterization, Subgrid SNOW Distribution (SSNOWD) model, into the land surface model MATSIRO. SSNOWD assumes the subgrid snow water equivalent depth distribution following the lognormal distribution function, and accounts for the subgrid snow physical processes. The 29-year simulation is conducted forced by the observation and reanalysis based meteorological data. The results are compared with satellite based observational dataset and the intra- and inter-annual snow cover fraction variations are validated. The effects of incorporating SSNOWD on hydrological properties are also evaluated. The results show that SSNOWD improves the intra- and inter-annual variability of snow cover area in Northern Hemisphere especially in the accumulation season and the effect of those changes in snow cover on the other land surface properties are not negligible.

DOI： 10.2208/jscejhe.68.I_325

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Language：Japanese  

CiNii Books

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Authorship：Lead author  

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Publisher：Japan Society of Civil Engineers  

Water footprints, or the total consumed water toproduce commodities, were estimated for imported food to Japan, using an integrated globalwater resources model that consists of a physically basedhydrological module and a cropgrowth module. In order to analyze the sustainability of water resources, the model was enhanced to quantify fourmajor sources: precipitation, river, reservoirs, and non-renewable groundwater. The results showed that the water footprint of Japan was 42.7km³/yr. The virtualwater, or the required amount of water that is needed toproduce the imported food domestically, wasestimated 62.7 km³/yr. Therefore, it indicates 20.0 km³/yr of water was saved through international trades. Among the total water footprint, 7.3 km³/yr (17%) was originated irrigation water, and 2.9 km³/yr (6.8%) was non-renewable groundwater.

DOI： 10.2208/prohe.52.367

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Language：English   Publisher：Japan Society of Hydrology and Water Resources (JSHWR) / Japanese Association of Groundwater Hydrology (JAGH) / Japanese Association of Hydrological Sciences (JAHS) / Japanese Society of Physical Hydrology (JSPH)  

We produced a new gauge-based analysis of daily precipitation over Japan from 1981 to 2000 on a 0.01&deg; grid. Wind-induced undercatch was adjusted at each observation station, and orographic effects were considered in the process of spatial interpolation from station data to the gridded product. The resulting gridded gauge-based analysis of precipitation was validated against observed river discharge data. The validation demonstrated that the product is reasonable, mostly because of the undercatch adjustment. Based on the resulting product, Japan receives nearly 2000 mm/year of precipitation on average, which is approximately 10% larger than commonly thought.

DOI： 10.3178/hrl.2.47

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