Recent studies have argued that extreme precipitation intensities are increased in many regions across the globe due to atmospheric warming. This argument is based on the principle of the Clausius-Clapeyron (CC) relationship, which states that the atmosphere can hold more moisture in warmer air temperatures (~7%°C–1). In this study, we investigate the future changes of extreme precipitation intensities associated with temperature over Japan, by analyzing multimodel ensemble downscaling experiments of three RCMs (NHRCM, NRAMS, WRF) driven by one GCM (MIROC3.2) for two climate periods (1981–2000 and 2081–2100, SRES A1B). We find that extreme precipitation intensities are significantly increased by 5–15 mm d–1 for temperatures above ~21°C in the future, compared to the current climate. The extreme precipitation intensities for lower (higher) temperatures below (above) 8–10°C (19–24°C) exhibit super-CC (negative-CC) scaling. The rate of increase of extreme precipitation intensities is also increased by ~2%°C–1 under the SRES A1B scenario (3.4–4.4%°C–1 during 1981–2000 and 5.5–6.5%°C–1 during 2081–2100). We find that the increase of extreme precipitation intensities is associated with strong vertical velocity and substantial increase of water vapor under the future scenario.
2016 Japan Society of Hydrology and Water Resources