Areas where "the heavy rainfall criterion is 1 mm / day or more" and “" mean rainfall amount exceeds the criterion" are colored as extreme rainfall areas.
The heavy rainfall criterion is the top 10% precipitation intensity (90th percentile) of the mean rainfall amount during the statistics period. The value in heavy rainfall areas is the corresponding from 90th to 99th percentile values.
Drought Index (SPI)
Standardized Precipitation Index (SPI) is a drought index that is able to calculate using only precipitation. The larger the negative value, the stronger the drought tendency.
NOAA/CPC Drought Indices Web site
The SPI calculation program was provided by NOAA/CPC.
The long-term average of precipitation (statistics period: April 2000 to March 2019). The unit is [mm / day].