Atmospheric Rivers Impacting Northern California Exhibit a Quasi-Decadal Frequency

In Northern California, much of the precipitation and surface water comes from atmospheric rivers–corridors of moisture transport from the tropics. The frequency of atmospheric rivers is cyclical, with periods of water surplus and deficit in the region that repeat every 10–17 years. While many social and political factors influence water resource distribution, understanding the climate factors that regulate water availability is important for managing water in the future. Using data from observations and modeling experiments, the pronounced wet/dry cycle in this area of the Western United States is mainly attributed to regular fluctuations in sea surface temperatures in the tropical Pacific Ocean. This analysis provides a potential source of predictability for atmospheric river frequency, and thus water availability, years before a winter season.