The relationship between ENSO events and California streamflows Available to Purchase

This study examines the relationships between types of extreme negative index phases of the Southern Oscillation and unimpaired stream volumes over California. Of particular interest in this investigation is the identification of subregions that appear to have consistent and strong El Niño/Southern Oscillation (ENSO) related streamflow signals. The analysis of 40 stations in California by an empirical approach indicates that apparent Type 1 ENSO‐related streamflow responses exist explicitly within the southern California and implicitly within the central and the northern California. The overall impact of the Type 1 ENSO events on the state is to produce a wet spell in streamflow commencing at the onset time of warm events continuing to the summer or early fall season of the year that follows the episode year. The relevant dynamical mechanisms concerning the observed relationships are discussed. Once an El Niño event sets in and the type (profile) of the event is identified by observing the zonal distribution of sea surface temperature in the equatorial Pacific during the summer, a long‐term prediction potential one or two seasons in advance may be available for California. The results of this analysis, confirming previous precipitation studies, also exhibit regionally specific midlatitude hydrologic responses to the tropical ENSO forcing.