Tropical cyclones act to intensify El Niño

Abstract

Tropical cyclones (TCs), some of the most influential weather events across the globe, are modulated by the El Niño–Southern Oscillation (ENSO). However, little is known about the feedback of TCs on ENSO. Here, observational and modelling evidence shows that TC activity in the southeastern western North Pacific can affect the Niño-3.4 index 3 months later. Increased TC activity in July–September can significantly contribute to the intensity of ENSO in October–December by weakening the Walker circulation and enhancing eastward-propagating oceanic Kelvin waves in the tropical Pacific. Thus, the greater the accumulated cyclone energy, the stronger (weaker) the El Niño (La Niña). A new physics-based empirical model for ENSO is constructed that significantly outperforms current models in predicting ENSO intensity from July to December and addressing the problem about the target period slippage of ENSO. Results suggest that TCs may provide significant cross-scale feedback to ENSO.

Global Estimate of Tropical Cyclone‐Induced Diapycnal Mixing and Its Links to Climate Variability

“…More and more evidence demonstrates that TC seems to have a positive impact on climate change (Q. Wang et al, 2019). PDO, as an indicator of climate variability on the interdecadal timescales, which is one of the dominant modes of climate variability in the North Pacific Ocean (Mantua et al, 1997).…”

Upper ocean response to tropical cyclones: a review

“…Some research even considers TCs is important to maintain the permanent El Niño in the early Pliocene epoch (Fedorov et al 2010). In addition to meridional heat transport, TCs can influence west wind bursts (Lian et al 2018(Lian et al , 2019, enhance eastward-propagating oceanic Kelvin waves in the tropical Pacific (Wang et al 2019b) and modulate the occurrence and development of the El Niño-Southern Oscillation. TCs usually cause plankton blooms, which contribute to local long-term primary productivity (Mooers 1975;Foltz et al 2015).…”

Feedback of tropical cyclones on El Niño diversity. Part I: Phenomenon

“…On interannual timescales, Camargo and Sobel (2005) first found an SST lagged signal using WNP accumulated cyclone energy (ACE) lag correlations with Niño indices for different seasons, and they suggested that ACE leads the Niño-3.4 index primarily because of the autocorrelation of SST anomalies in the Niño-3.4 region. Wang et al (2019) found that the preceding (3 months earlier) WNP TCs could actually affect the El Niño intensity by a cumulative effect: the greater the ACE, the stronger the El Niño, particularly for TCs in July-September.…”

“…In recent 20 years, the influence of TCs on the atmospheric and oceanic environment has attracted much interest (Sobel and Camargo 2005;Wada and Chan 2008), and the possible climate effects of TCs are coming under scrutiny (Hart 2011;Schenkel and Hart 2015). Previous studies (Hart et al 2007;Wang et al 2019) showed that the local memory of atmospheric and oceanic changes associated with a TC can persist over an extended period, so that TCs could contribute to the variation of SST over the eastern Pacific: the numerical experiments involving specified TC cases (Sriver et al 2013) indicate TCs can excite equatorial Kelvin and Yanai waves, further suggesting that TC wind forcing may affect the timing and amplitude of El Niño events. Cross-equatorial TC pairs also play a role in the eastward expansion of equatorial warm SST anomalies in the Pacific (Keen 1982).…”