d4PDF: large-ensemble and high-resolution climate simulations for global warming risk assessment

Abstract

A large-ensemble climate simulation database, which is known as the database for policy decision-making for future climate changes (d4PDF), was designed for climate change risk assessments. Since the completion of the first set of climate simulations in 2015, the database has been growing continuously. It contains the results of ensemble simulations conducted over a total of thousands years respectively for past and future climates using high-resolution global (60 km horizontal mesh) and regional (20 km mesh) atmospheric models. Several sets of future climate simulations are available, in which global mean surface air temperatures are forced to be higher by 4 K, 2 K, and 1.5 K relative to preindustrial levels. Nonwarming past climate simulations are incorporated in d4PDF along with the past climate simulations. The total data volume is approximately 2 petabytes. The atmospheric models satisfactorily simulate the past climate in terms of climatology, natural variations, and extreme events such as heavy precipitation and tropical cyclones. In addition, data users can obtain statistically significant changes in mean states or weather and climate extremes of interest between the past and future climates via a simple arithmetic computation without any statistical assumptions. The database is helpful in understanding future changes in climate states and in attributing past climate events to global warming. Impact assessment studies for climate changes have concurrently been performed in various research areas such as natural hazard, hydrology, civil engineering, agriculture, health, and insurance. The database has now become essential for promoting climate and risk assessment studies and for devising climate adaptation policies. Moreover, it has helped in establishing an interdisciplinary research community on global warming across Japan.

Atmospheric Rivers Bring More Frequent and Intense Extreme Rainfall Events Over East Asia Under Global Warming

“…We use a set of ensemble simulations with an AGCM and a RCM from the database for Policy Decision making for Future climate change (d4PDF, Ishii & Mori, 2020; Mizuta et al., 2017). The AGCM used in the d4PDF is the Meteorological Research Institute AGCM version 3.2 (MRI‐AGCM3.2; Mizuta et al., 2012) with 60‐km horizontal resolution and 64 vertical layers.…”

Effects of Internal Climate Variability on Historical Ocean Wave Height Trend Assessment

“…The 100 historical simulations constitute a SMILE-type ensemble as they were generated by perturbations of the historical sea surface temperature (SST), sea ice concentration (SIC) and sea ice thickness (SIT) in relation to the observed errors (while using the same forcing, and global mean concentration of greenhouse gases (GHG) based on observations). More than 70 papers related to d4PDF have been published to date, including impact assessment and social implementation studies (Ishii and Mori, 2020). d4PDF satisfactorily simulates the past climate in terms of climatology, natural variations, and extreme events such as tropical cyclones (Ishii and Mori, 2020).…”

“…More than 70 papers related to d4PDF have been published to date, including impact assessment and social implementation studies (Ishii and Mori, 2020). d4PDF satisfactorily simulates the past climate in terms of climatology, natural variations, and extreme events such as tropical cyclones (Ishii and Mori, 2020).…”

“…In terms of annual hurricane frequency, Mei et al (2019) concluded that twenty ensemble was sufficient to detect year-to-year variations. The number of ensemble members required for robust estimates depends on targets or on temporal and spatial averaging scale (Ishii and Mori, 2020).…”

Potential Seasonal Predictability of the Risk of Local Rainfall Extremes Estimated Using High‐Resolution Large Ensemble Simulations

“…The difference between 60-km and 20-km grid spacing is critical for representing the weather in an island nation like Japan (Figure S1 in Supporting Information S1). The accuracy of typhoons, the Baiu front, and associated extreme rainfall simulated by d4PDF was verified in Ishii and Mori (2020), Yoshida et al (2017), and Kawase et al (2019).…”