Abstract
Santa Ana wind (SAW) events have great implications for the environment of Southern California, but the cause of their decadal variability has not been fully understood. We show with observational analysis that the Atlantic multi-decadal oscillation (AMO) has a stronger influence than the Pacific decadal oscillation (PDO) in modulating SAW activity through two mechanisms: the Great Basin pressure gradient mechanism, in which a strengthened Great Basin high promotes SAW activity and vice versa through the northeast–southwest pressure gradient across Southern California, and the Pacific jetstream displacement mechanism, in which a strengthened Pacific subtropical high (PSH) prohibits mid-latitude cyclones from traveling toward California, consequently encouraging SAW development and vice versa. While the AMO strengthens or weakens both the Great Basin and PSHs to strongly modulate SAW activity through these two mechanisms, the PDO strengthens one of the highs but weakens the other, causing the two mechanisms to cancel each other, producing little influence on SAW activity. A projection based on the AMO and PDO indicates that the above-average SAW activity observed since the beginning of the 21st century is likely to terminate after 2016, after which Southern California may experience an extended period of below-average SAW activity through 2030.
Highlights
The Santa Ana winds (SAWs) are a weather phenomenon in Southern California that occur most often during late autumn to early spring (e.g., Conil and Hall 2006)
We examined the decadal variation of the SAW activity and its connection with the decadal variability modes in the Pacific and Atlantic during 1960–2010
The correlation and regression analyzes using reanalysis datasets and climate indices revealed that the Atlantic multi-decadal oscillation (AMO) has a stronger influence than the Pacific decadal oscillation (PDO) on the decadal variability of the SAW through the Great Basin high (GBH)—pressure gradient mechanism and the Pacific subtropical high (PSH)—jetstream displacement mechanism
Summary
While the AMO strengthens or weakens both the Great Basin and PSHs to strongly modulate SAW activity through these two mechanisms, the PDO strengthens one of the highs but weakens the other, causing the two mechanisms to cancel each other, producing little influence on SAW activity. SAW activity observed since the beginning of the 21st century is likely to terminate after 2016, after which Southern California may experience an extended period of below-average SAW activity through 2030
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
