Time series of the Hawai‘i Rainfall Index from 1905 to 2010, showing decreasing trend for 1980-2009



Figure 2-5  Annual normalized and dimensionless (July to June) time series of the Hawai‘i Rainfall Index (HRI) from 1905 to 2010. As shown in the plot, the trend for the first epoch (1905–1979) is basically flat, while for the second epoch (1980–2009) the decreasing trend is apparent. Nine stations each from Kaua‘i, O‘ahu, and Hawai‘i are used. These 27 stations represent the spatial variability of rainfall with regard to trade wind exposure and elevation. (Updated from Chu & Chen, 2005.)