In order to re-examine the formation process of the climatological precipitation difference between Kochi (Pacific side of Shikoku District) and Okayama (Seto Inland Sea side) characterizing the Seto Island Sea Climate in warm season, synoptic climatological analyses of the daily precipitation features and atmospheric fields were performed for the warm season (April to September) of 1985 - 2015, based on the daily and hourly precipitation data and weather maps by the Japan Meteorological Agency (JMA), and the NCEP/NCAR re-analysis data. The large climatological difference of precipitation at Kochi from that at Okayama throughout the warm season was greatly contributed to by the days with the precipitation difference between Kochi and Okayama (ΔPR) with greater equal to 30 mm/day. In addition, such large daily ΔPR was mainly due to the intense rainfall at Kochi with greater equal to 10mm/h throughout the warm season, except for a part of the cases in April when the “not so intense rain” with less than 10mm/h at Kochi contributed to the large ΔPR. However, it is noted that the features of the synoptic-scale atmospheric fields and possible roles of the mountain ranges in Shikoku District causing the large ΔPR were rather different among August (midsummer), September (Autumn rainfall season) and April (Spring) .
Daily precipitation climatology
Climate around Japan
Seto Inland Sea Climate in Japan