An analysis of warm pool and cold tongue El Niños: air–sea coupling processes, global influences, and recent trends

Abstract

The differences in tropical air-sea interactions and global climate connection as well as the hindcast skills for the warm pool (WP) and cold tongue (CT) El Niños are investigated based on observed, (re)analyzed, and model hindcast data. The robustness of observed global climate connection is established from the model simulations. Lastly, variations of atmosphere and ocean conditions in the recent decades, and their possible connection with the frequency increase of the WP El Niño are discussed. Consistent with previous results, our individual case study and composite results suggest that stronger (weaker) and more eastward extended (westward confined) westerly wind along the equatorial Pacific in early months of a year is associated with active (suppressed) air-sea interaction over the cold tongue/the Intertropical Convergence Zone complex, as well as more (less) intensive oceanic thermocline feedback, favoring the CT (WP) El Niño development. The preceding westerly wind signal and air-sea interaction differences may be responsible for the predication skill difference with higher (lower) overall hindcast skill for the CT (WP) El Niño in the Climate Forecast System of National Centers for Environmental Prediction.Our model experiments show that, in addition to the tropics, the eastern Pacific, North America and North Atlantic are the major regions having robust climate differences between the CT and WP El Niños. Nevertheless, the climate contrasts seem not robust over the Eurasian continent. Also, the frequency increase of the WP El Niño in the recent decades may not be directly connected with the linear trend of the tropical climate.

Predictable patterns and predictive skills of monsoon precipitation in Northern Hemisphere summer in NCEP CFSv2 reforecasts

“…The observed PC1 of AIPM precipitation (Fig. 11a) is connected with a central Pacific El Niño-like SST anomaly pattern with significant positive correlation in the central and eastern tropical Pacific and negative correlation in the western tropical Pacific, consistent with the central Pacific El Niño composite pattern shown in Hu et al (2012b). The simultaneous correlation coefficient is 0.84 between the observed PC1 and Niño 3.4 SST.…”

The non-linear impact of El Niño, La Niña and the Southern Oscillation on seasonal and regional Australian precipitation

“…The EN-LN asymmetry has been shown to affect the rainfall distribution over North America, particularly for strong events (Hoerling et al 1997;Power et al 2006), Papua New Guinea (Smith et al 2013), several tropical Pacific island nations (Murphy et al 2014) and New Zealand (Mullan 2008). Differences in the location of the Pacific SST anomalies during EN events also produce significantly different temperature and precipitation anomalies over North America and the North Atlantic (Hu et al 2012). Atmospheric general circulation model experiments using prescribed SSTs have also shown that linearly varying the magnitude of an EN event produces a large non-linear precipitation increase over the equatorial Pacific Ocean and an eastward shift of the rainfall patterns along the equator Power et al 2013).…”

A Source of AGCM Bias in Simulating the Western Pacific Subtropical High: Different Sensitivities to the Two Types of ENSO

“…These two terms were introduced by Yu and Kao (2007) and Kao and Yu (2009) to emphasize the different longitudinal locations of these types of ENSO. Many studies have revealed that the CP ENSO can affect global and regional climate differently from the EP ENSO (e.g., Larkin and Harrison 2005;Hu et al 2012;Yu et al 2012b). The CP ENSO has occurred more frequently in the past few decades (Ashok et al 2007;Kao and Yu 2009;Kug et al 2009).…”