In order to examine year-to-year variability of the Akisame (autumn rainfall) frontal zone in East Asia, large-scale cloud distribution and atmospheric fields around the frontal zone were compared among 1993, 1994 and 1995, when their characteristics were rather different among each other. While the Akisame frontal zone extended zonally and the deep convective clouds tended to appear in that frontal zone near the southern coast of the Japan Islands in 1993, the frontal zone extends from southwest to northeast and the large amount of precipitation was brought mainly in the northern Japan. In 1995, although the surface front on the weather maps appeared frequently also around the southern coast of the Japan Islands, the rainfall amount there was not so large. The area with frequent appearance of the deep convective clouds in the Akisame frontal zone was seen only to the east of the Japan Islands. As such, it is noted that the active area of the Akisame frontal zone shows rather large year-to-year variability also in the zonal direction. It is also suggested that such great variability of the Akisame frontal zone in the zonal direction seems to correspond to the
variations of the subtropical high and the ITCZ in the western Pacific region around September.
Akisame (autumn rainfall) front
STFZ in early autumn
year-to-year difference of Akisame front