Observational and modeling studies show that the relative frequency of El Niño and La Niña varies in association with El Niño–Southern Oscillation (ENSO)‐like tropical Pacific decadal variability (TPDV), but the causality of the linkage remains unclear. This study presents evidence that ENSO‐like TPDV affects the frequency of ENSO events, particularly of El Niño, through a set of climate model experiments. During the positive phase of TPDV, tropical Pacific warming relative to the Indian and Atlantic Oceans increases the occurrence of anomalous westerly winds over the western equatorial Pacific in late boreal winter‐spring, triggering more El Niño and fewer La Niña events. The opposite happens for the negative TPDV phase. The La Niña frequency is also influenced by oceanic adjustments following El Niño, which tends to counteract the effect of wind changes. The mean state control of ENSO offers a potential opportunity for decadal predictions of climate extremes.
Rainfall in southern California is highly variable, with some fluctuations explainable by climate patterns. Resulting runoff and heightened streamflow from rain events introduces freshwater plumes into the coastal ocean. Here we use a 105-year daily sea surface salinity record collected at Scripps Pier in La Jolla, California to show that El Niño Southern Oscillation and Pacific Decadal Oscillation both have signatures in coastal sea surface salinity. Averaging the freshest quantile of sea surface salinity over each year’s winter season provides a useful metric for connecting the coastal ocean to interannual winter rainfall variability, through the influence of freshwater plumes originating, at closest, 7.5 km north of Scripps Pier. This salinity metric has a clear relationship with dominant climate phases: negative Pacific Decadal Oscillation and La Niña conditions correspond consistently with lack of salinity anomaly/ dry winters. Fresh salinity anomalies (i.e., wet winters) occur during positive phase Pacific Decadal Oscillation and El Niño winters, although not consistently. This analysis emphasizes the strong influence that precipitation and consequent streamflow has on the coastal ocean, even in a region of overall low freshwater input, and provides an ocean-based metric for assessing decadal rainfall variability.
more » « less- PAR ID:
- 10409610
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Communications Earth & Environment
- Volume:
- 4
- Issue:
- 1
- ISSN:
- 2662-4435
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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