A Five-Century Reconstruction of Hawaiian Islands Winter Rainfall
AbstractFew if any high-resolution (annually resolved) paleoclimate records are available for the Hawaiian Islands prior to ~1850 CE, after which some instrumental records start to become available. Here we show how atmospheric teleconnection patterns between North America and the Northeast North Pacific (NNP) allow for reconstruction of Hawaiian Islands rainfall using remote proxy information from North America. Based on a newly available precipitation data set for the State of Hawai‘i and observed and reconstructed December–February (DJF) sea level pressures (SLP) in the North Pacific Ocean, we make use of a strong relationship between winter SLP variability in the Northeast Pacific and corresponding DJF Hawai‘i rainfall variations to reconstruct and evaluate that season’s rainfall over the period 1500–2012 CE. A general drying trend, though with substantial decadal and longer-term variability, is evident, particularly during the last ~160 years. Hawaiian Islands rainfall exhibits strong modulation by El Niño/Southern Oscillation (ENSO), as well as in relation to Pacific Decadal Oscillation (PDO)-like variability. For significant periods of time, the reconstructed large-scale changes in the North Pacific SLP field described here, and by construction the long-term decline in Hawaiian winter rainfall are broadly consistent with long-term changes in tropical Pacific sea surface temperature (SST) based on ENSO reconstructions documented in several other studies, particularly over the last two centuries. We also note some rather large multi-decadal fluctuations in rainfall (and hence in NNP SLP) in the 18th century of undetermined provenance.