• Energy Research
• JP close
• Japanese close
• Kyoto University close

It has been increasingly important to project the future risk of small-scale torrential rainfall in summer, called ‘Guerrilla-heavy rainfall' in urban areas in Japan. In this study, we implemented some analysis in August in Kinki Region, from the view point of both the rainfall distribution and the unstable atmospheric condition. First, we picked up Guerrilla-heavy rainfall events with both tracking algorism and visual judgement of rainfall distribution of NHRCM05 output. Then, we analyzed the atmospheric stability of the events that was picked up, using a parameter SSI (Showalter Stability Index). As a result of T-test, it is implied that the number of days having Guerrilla-heavy rainfall will significantly increase at the end of August, and that this tendency corresponded to the more unstable SSI in the future. In conclusion, the season when Guerrilla-heavy rainfall is likely to occur will be longer in the future summer, with the more unstable SSI at the end of August

It has been increasingly important to project the future risk of small-scale torrential rainfall in summer, called ‘Guerrilla-heavy rainfall' in urban areas in Japan. In this study, we implemented some analysis in August in Kinki Region, from the view point of both the rainfall distribution and the unstable atmospheric condition. First, we picked up Guerrilla-heavy rainfall events with both tracking algorism and visual judgement of rainfall distribution of NHRCM05 output. Then, we analyzed the atmospheric stability of the events that was picked up, using a parameter SSI (Showalter Stability Index). As a result of T-test, it is implied that the number of days having Guerrilla-heavy rainfall will significantly increase at the end of August, and that this tendency corresponded to the more unstable SSI in the future. In conclusion, the season when Guerrilla-heavy rainfall is likely to occur will be longer in the future summer, with the more unstable SSI at the end of August

With the growing importance of taking stepwise adaptation measures to climate change, we conducted a future change analysis of rainfall during the baiu rainy season using 150-year continuous run. We analyzed two aspects about the baiu rainfall: baiu frontal zones based on average daily rainfall in July and baiu extreme rainfall based on hourly rainfall. The results show that the rainfall area gradually moves northward in both the frontal zone and location of the extreme rainfall events. The analysis of future changes in average daily rainfall by region showed that there was a marked tendency for rainfall to in-crease in northern Japan, but there were also regions that contained periods when rainfall was lower than the historical average. The reasons for this are discussed in terms of the influence of sea surface temperatures and typhoons. Furthermore, we showed that the duration of extreme rainfall events will gradually increase in the future.

With the growing importance of taking stepwise adaptation measures to climate change, we conducted a future change analysis of rainfall during the baiu rainy season using 150-year continuous run. We analyzed two aspects about the baiu rainfall: baiu frontal zones based on average daily rainfall in July and baiu extreme rainfall based on hourly rainfall. The results show that the rainfall area gradually moves northward in both the frontal zone and location of the extreme rainfall events. The analysis of future changes in average daily rainfall by region showed that there was a marked tendency for rainfall to in-crease in northern Japan, but there were also regions that contained periods when rainfall was lower than the historical average. The reasons for this are discussed in terms of the influence of sea surface temperatures and typhoons. Furthermore, we showed that the duration of extreme rainfall events will gradually increase in the future.

The statistical property of wind power fluctuation, which does not fit to the normal distribution because of its high probability of the extremal outlier, is regarded as a source of severe damage to power systems. In view of this, the authors have proposed an evaluation method for the impact of wind power fluctuation on power system quality, assuming that this heavy-tailed uncertainty obeys a power-law. In this paper, we first examine the validity of this assumption based on real data of frequency deviation under wind power interconnection. Then, the evaluation method is improved by extending theoretical results, and is applied to analysis of load frequency control model to verify its advantage over Monte Carlo methods.

The statistical property of wind power fluctuation, which does not fit to the normal distribution because of its high probability of the extremal outlier, is regarded as a source of severe damage to power systems. In view of this, the authors have proposed an evaluation method for the impact of wind power fluctuation on power system quality, assuming that this heavy-tailed uncertainty obeys a power-law. In this paper, we first examine the validity of this assumption based on real data of frequency deviation under wind power interconnection. Then, the evaluation method is improved by extending theoretical results, and is applied to analysis of load frequency control model to verify its advantage over Monte Carlo methods.

Pseudo global warming experiments (PGW) were conducted with 1000m and 500m horizontal resolution for the 2012 Kameoka extreme rainfall event, which was the type of back-building convection system. As a result, the back-building system was very well represented in both of present and PGW experiments, and the rainfall intensity and total rainfall increased in PGW experiments. This is due to the fact that: in the future, the amount of condensation in cumulonimbus will increase and a convective unstable field will be realized (meso γ ~ β), the back-building structure will be strengthened (meso β), and the convective unstable atmosphere was continuously supplied from the south (meso α). We also showed that the result of 500m resolution can represent the back-building system much better than that of 1000m because 1000m resolution can capture future changes in meso-α, but cannot capture changes smaller than meso-β sufficiently.

Pseudo global warming experiments (PGW) were conducted with 1000m and 500m horizontal resolution for the 2012 Kameoka extreme rainfall event, which was the type of back-building convection system. As a result, the back-building system was very well represented in both of present and PGW experiments, and the rainfall intensity and total rainfall increased in PGW experiments. This is due to the fact that: in the future, the amount of condensation in cumulonimbus will increase and a convective unstable field will be realized (meso γ ~ β), the back-building structure will be strengthened (meso β), and the convective unstable atmosphere was continuously supplied from the south (meso α). We also showed that the result of 500m resolution can represent the back-building system much better than that of 1000m because 1000m resolution can capture future changes in meso-α, but cannot capture changes smaller than meso-β sufficiently.

In this study, we analyze the mechanism of the future change of a occurrence frequency of Guerrilla-heavy rainfall in the Kinki region in August by focusing on the future change of lapse rate and water vapor inflow using a 5km-mesh regional climate model (RCM05). From the analysis, we show the frequency of days will increase when Showalter Stability Index (SSI), which expresses atmospheric stability, becomes lower in the Kinki region in late August although lapse rate will decrease. Lower SSI means that atmosphere is unstable. Then we show that the reason of destabilization of SSI is the increase of water vapor in lower layer. Finally, we use Self-Organizing Map (SOM), which is one cluster classification method, to reveal the main reason of the increase of water vapor in the lower layer in late August. The results show the wind field which blows from the Pacific to the Kinki region is increasing, and this explains rich water vapor flux is supplied to the Kinki region.

In this study, we analyze the mechanism of the future change of a occurrence frequency of Guerrilla-heavy rainfall in the Kinki region in August by focusing on the future change of lapse rate and water vapor inflow using a 5km-mesh regional climate model (RCM05). From the analysis, we show the frequency of days will increase when Showalter Stability Index (SSI), which expresses atmospheric stability, becomes lower in the Kinki region in late August although lapse rate will decrease. Lower SSI means that atmosphere is unstable. Then we show that the reason of destabilization of SSI is the increase of water vapor in lower layer. Finally, we use Self-Organizing Map (SOM), which is one cluster classification method, to reveal the main reason of the increase of water vapor in the lower layer in late August. The results show the wind field which blows from the Pacific to the Kinki region is increasing, and this explains rich water vapor flux is supplied to the Kinki region.

In ENEMANE HOUSE 2017, we proposed a sustainable renovation project named “Machiya + Core”, in which a model house with both traditional appearance and high energy performance was built. Energy saving technique including new solar photovoltaic power generation system and thermal comfort improvement was intended in the environmental design process. The thermal environment and energy consumption were measured in the model house, and the possibility and challenges for the ZEH renovation of traditional townhouses were examined.

In ENEMANE HOUSE 2017, we proposed a sustainable renovation project named “Machiya + Core”, in which a model house with both traditional appearance and high energy performance was built. Energy saving technique including new solar photovoltaic power generation system and thermal comfort improvement was intended in the environmental design process. The thermal environment and energy consumption were measured in the model house, and the possibility and challenges for the ZEH renovation of traditional townhouses were examined.