Today's article was taken from the online version of the Yomiuri Newspaper.
Coming from America, I have always been familiar with a year that has 4 seasons: spring, summer, winter and fall. In contrast, Japan actually has a year that has 5 seasons. It has the normal four seasons plus a rainy season that lasts from around the end of May to the beginning of July. The start and the total length of the season depends on when the heavy rain starts and stops. All in all, it's a miserable season for those of you that don't like hot, humid and rainy days.
Maybe it is because Japan has a deep connection (sometimes hate) of their 5th season that Japanese scientists have felt the need to study its properties. Way back in 1901 scientists erected 37 rain collection stations scattered all throughout Japan. The amount of fallen rain at different points in the rainy season was noted from 1901 to 2009 (it is still probably being noted now, but for this study the data stops at 2009).
The scientists at the Meteorological Society of Japan (MSJ), have decided to take the average of the amount of rain that fell from 1901 to 1930 and set that as the benchmark for future comparisons. In other words the average from 1901 to 1930 is set as the normal rain level and all future averages are compared to it.
The MSJ found a few interesting trends after they correlated the data. First is the good news, the amount of rain that falls in the begining of the rainy season has been decreasing over time. In fact there has been a 20% decrease from the 1901 to 1930 average. Now for the bad news, as the end of the rainy season the amount of rain that falls on the Japan Sea side of Japan has increased to about 2.5 times the 1901 to 1930 average. On the other hand, the amount of rainfall on the ocean side of Japan has not really changed much. These trends can be seen in the graph below.
|The blue in the graph is the ocean side of Japan, while the red is the Japan Sea side.|