Recent positive trend in heavy rainfall in eastern Japan and its relation with variations in atmospheric moisture

A recent trend in heavy rainfall in eastern Japan was studied using 31 years' worth of AMeDAS (19762006) hourly rainfall data having fine spatial resolution. The non-parametric Wilcoxon rank-sum test was applied to the heavy rainfall in two 10-year periods (19801989 and 19972006), and the trends determined were compared with recent variations in atmospheric moisture.