This paper clarifies that the skillful time-scale characteristic of a model is one of the key factors to reproduce the amount precipitation at a specific place with the model. A comparison with data from an operational observing site of the Japan Meteorological Agency in Tokyo revealed that a model needed at least 5-km-grid resolution (NHRCM05) to represent the power spectrum of hourly precipitation.
Figure 1 indicates the PDF of hourly precipitaion around the Tokyo site. It is difficult to characterize extreme hourly precipiation by using the AGCM20/60 models. However, the NHRCM05 model could simulate extreme precipitaion events.
To clarify the cause of the difference, we obtained a power spectrum of precipitaion (Fig.2). We found that they were very similar at frequencies lower than 1 cycle per day (CPD). However, at frequencies greater than 1CPD, the simulated power was lower in lower resolution models (AGCM20/60).