Interannual and interdecadal rainfall variations in the Hawaiian Islands

Abstract

The effect of El Nino-Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) on Hawaiian precipitation has been documented by many researchers. In this observational study, the long-term monthly precipitation data are used to examine the combined effect of ENSO and PD~ on Hawaiian precipitation. The results are as follows: (1) The interseasonal, interannual and interdecadal variability are the dominant frequencies of Hawaiian monthly precipitation. (2) Hawaiian winter rainfall is negatively correlated with PDO and ENSO; however, Hawaiian summer rainfall is positively correlated with PDO and ENSO. (3) The synergetic match of PD~ and ENSO phases (i.e., El Nino/+PDO or La Nina/PDO) enhances the ENSO-induced Hawaiian rainfall and circulation patterns in the North Pacific, while the opposite match (i.e., La Nina/+PDO, El Nino/-PDO) tends to weaken the ENSO influence on Hawaiian rainfall and circulation patterns. (4) The preceding Nino 3.4 index and PDO index provide similar information for predicting the following Hawaiian winter precipitation. The potential predictability of winter rainfall is enhanced, when using both the PDO index and the Nino 3.4 index.