The data includes the version 6 monthly TMPA (3B43 V.6). Twelve years (2000–2011) of TMPA
monthly precipitation data with a 0.25°×0.25° spatial resolution were provided by TRMM Science
Data and Information System (TSDIS) and distributed by the NASA GSFC Distributed Active Archive
Center (GDAAC).The images were rotated and reprojected to UTM projection with ENVI 4.7, and the
outline of North Korea was extracted with ArcGis10. In this study, we focused only on the summer
season from July to September. The value of each pixel is the rate of rainfall; each image represents a
relevant month, so each image is multiplied by the whole hours of the month. In this study, the average
value wsa used to represent the average precipitation in each month in every year. So there are 12
average precipitation figures for calculating the Z index in each month.