Abstract
The El Niño-Southern Oscillation (ENSO) is a dominant source of global climate variability. The effects of this phenomenon alter the flow of heat from tropical to polar latitudes, resulting in weather and climate anomalies that are difficult to forecast. The current work quantified two components of the vertically integrated equation for the total energy content of an atmospheric column, to show the anomalous horizontal redistribution of surface heat flux anomalies. Symmetric and asymmetric components of the vertically integrated latent and sensible heat flux divergence were quantified using ERA-Interim atmospheric reanalysis output on 30 model layers between 1979 and 2016. Results indicate that asymmetry is a fundamental component of ENSO-induced weather and climate anomalies at the global scale, challenging the common assumption that each phase of ENSO is equal and opposite. In particular, a substantial asymmetric component was identified in the relationship between ENSO and patterns of extratropical climate variability that may be proportional to differences in sea surface temperature anomalies during each phase of ENSO. This work advances our understanding of the global distributions of source and sink regions, which may improve future predictions of ENSO-induced precipitation and surface temperature anomalies. Future studies should apply these methods to advance understanding and to validate predictions of ENSO-induced weather and climate anomalies.
Highlights
Coupled atmosphere–hydrosphere interactions have gained attention in recent decades, given the recognition of the El Niño-Southern Oscillation (ENSO) as a dominant source of inter-annual climate variability [1]
Across the northeast Pacific Ocean, a strongly anomalous (>600 kJ m−2 s−1 ) region of anomalous sensible heat flux convergence was located between 30◦ N and 60◦ N during El Niño events, whereas La Niña events were characterized by strongly anomalous divergence (Figure 1)
Results of the current work indicated that El Niño events resulted in larger anomalies along the east coast of North America, whereas La Niña resulted in larger anomalies across Europe, suggesting that a distinct relationship exists between North Atlantic Oscillation (NAO) and each phase of ENSO
Summary
Coupled atmosphere–hydrosphere interactions have gained attention in recent decades, given the recognition of the El Niño-Southern Oscillation (ENSO) as a dominant source of inter-annual climate variability [1]. El Niño and La Niña events are described through the analysis of sea surface temperature (SST) anomalies within the Niño 3.4 region Atmosphere 2018, 9, 342 phase of the ENSO phenomena, and both phases typically reach peak magnitude during the month of December when the SST anomaly variance is maximized in the Niño 3.4 region [4]. Longitudinal gradients in MSLP associated with the Southern Oscillation influence the magnitude, and in some cases, the direction (i.e., westerly wind bursts [6]) of the equatorial easterly trade winds [7]. The combination of anomalous SSTs (i.e., El Niño or La Niña) and wind patterns (i.e., Southern Oscillation) force anomalous heat fluxes at the ocean-atmosphere interface, altering the flow of heat from tropical to polar latitudes [1,8]
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