Central Pacific (CP) and Eastern Pacific (EP) type ENSO events are inves-2 tigated using linear inverse modeling (LIM). Optimal initial conditions and growth 3 rates for CP or EP ENSO events are identified explicitly using a CP or EP ENSO 4 norm. The dominant difference in initial conditions that lead to CP and EP ENSO 5 events is the role of the second empirical orthogonal function of tropical...

Focusing on ENSO seasonal phase locking, diversity in peak location, and propagation direction, as well as the El Niño–La Niña asymmetry in amplitude, duration, and transition, a set of empirical probabilistic diagnostics (EPD) is introduced to investigate how the ENSO behaviors reflected in SST may change in a warming climate. EPD is first applied to estimate the natural variation of ENSO beha...

Numerical experiments with a coupled model have been carried out to test the heat-pump hypothesis for ENSO. The hypothesis states that the level of ENSO activity is controlled by the meridional differential surface heating over the Pacific: either an enhanced surface heating over the equatorial region or an enhanced cooling over the subtropical/extratropical ocean may result in a regime with st...

The El Niño phenomenon, synonymously El Niño-Southern Oscillation (ENSO), is an anomalous climatic oscillation in the Equatorial Pacific that occurs once every 3-8 years. It affects the earth’s climate on a global scale. Whether it is a cyclic or a sporadic event, or whether its apparently random behaviour can be explained by stochastic dynamics have remained matters of debate. Herein ENSO is v...

[1] The effect of the Indian Ocean on El Niño/La Niña life cycles has been studied using 200-yrs simulation data of a coupled GCM. The results show that the interactive feedback between the ENSO and the Indian Ocean holds the key to the rapid transition to an opposite phase. This remote impact of the IndianOceanSSTanomaly is linked to the change of zonal wind stress in the western Pacific, whic...

The conceptual El Niño–Southern Oscillation (ENSO) recharge oscillator model is used to study the linear stability of ENSO under state-dependent noise forcing. The analytical framework developed by Jin et al. is extended to more fully study noise-induced instability of ENSO. It is shown that in addition to the noise-induced positive contribution to the growth rate of the ensemble mean (first mo...

Methane (CH4 ) emissions from tropical wetlands contribute 60%-80% of global natural wetland CH4 emissions. Decreased wetland CH4 emissions can act as a negative feedback mechanism for future climate warming and vice versa. The impact of the El Niño-Southern Oscillation (ENSO) on CH4 emissions from wetlands remains poorly quantified at both regional and global scales, and El Niño events are exp...

[1] The effect of the El Niño/Southern Oscillation (ENSO) on tropical rainfall variations of the past 2 millennia is largely unknown. High-resolution monsoon records are sparse, despite the role of ENSO in generating global hydrologic anomalies in modern climate. To investigate the relationship between ENSO and the Central American Monsoon, we generated a high-resolution ( 2.9 years/sample) oxy...

El Niño-Southern Oscillation (ENSO) is a major source of global interannual variability, but its response to climate change is uncertain. Paleoclimate records from the Last Glacial Maximum (LGM) provide insight into ENSO behavior when global boundary conditions (ice sheet extent, atmospheric partial pressure of CO2) were different from those today. In this work, we reconstruct LGM temperature v...

Recent studies have identified clear climate feedbacks associated with interannual variations in freshwater forcing (FWF) and ocean biology-induced heating (OBH) in the tropical Pacific. The interrelationships among the related anomaly fields are analyzed using hybrid coupled model (HCM) simulations to illustrate their combined roles in modulating the El Niño-Southern Oscillation (ENSO). The HC...