Atmospheric moisture transport and its impact on the water cycle over Alaska and Hawaii: the roles of the Pacific Decadal Oscillation and El Nino

Abstract

Precipitation over the North Pacific can fluctuate under climate patterns such as the Pacific Decadal Oscillation (PDO) and El Niño-Southern Oscillation (ENSO). In order to better understand the role which these climatic patterns play in the North Pacific water budgets and pathways, we employed the Community Atmosphere Model 5.0 (CAM) and conducted sensitivity experiments to examine how atmospheric moisture convergence and moisture transport respond to sea surface temperature (SST) anomalies associated with the PDO and ENSO phase transitions. We have found that changes in transient moisture transport, as the PDO phase shifts from cool to warm, are due to increases in specific humidity and decreases in wind speeds over Alaska and the North Pacific. Additionally, increases in moisture convergence, specific humidity, and wind speeds and decreases in transient moisture transport are seen over the North Pacific during El Niño events compared to La Niña events.