Towards a better understanding of the El Niño-Southern Oscillation (ENSO): Pattern, mechanism, impacts and prediction
Jianjun Xu, George Mason University, Fairfax, USA
Alfred M. Powell Jr, The Center for Satellite Applications and Research (STAR), NESDIS/NOAA, USA
Wen Zhou, City University of Hong Kong, Hong Kong, China
Ke Fan, IAP
Shiqiu Peng, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
El Niño-Southern Oscillation (ENSO) is an ocean-atmosphere coupled interannual phenomenon with a complicated spatial structure and temporal evolutions. The mechanisms of the ENSO evolution originated from the positive feedback processes postulated by Bjerknes. The shifts between El Niño and La Niña phases can be explained by some theories such as the delayed oscillator, the thermal recharge and discharge in equatorial western Pacific, and so on. Usually, the El Niño events can be categorized into different types in terms of spatial patterns of sea surface temperature anomalies or the onset time of these events. More and more studies on this issue have been published in recent years.
The sea surface temperature anomaly (SSTA) of different El Niño events emerge in different patterns. Two major types of SSTA patterns have been identified through the spatial structure of SSTA. One is the Eastern Pacific El Niño and the other is the Central Pacific El Niño. Even though there are some differences in both the definitions and the coined names of different El Niño types as reported from different research groups, the physical essence of these definitions are similar to each other. The Eastern Pacific pattern is typical of the maximum anomalous warming in the Eastern Pacific while the Central Pacific pattern has the largest warming neighboring the Central Pacific. For example, one study defined two types of El Niño events in terms of the spatial patterns of the SSTA seasonal mean from September to the following February. The Niño-3 SSTA was used to measure the intensity of cold tongue (CT) El Niño events with higher SSTAs in the Eastern Pacific while Niño-4 SSTA was used to define warm pool (WP) El Niño events possessing higher SSTAs in the Central and Western Pacific. However, the criterion of the Niño-3 SSTA or Niño-4 SSTA makes it difficult to completely separate the pattern of SSTA into CT or WP type of El Niño events. As a result, a third pattern with a combination of CT and WP characteristics was designated as a Mixed pattern. In addition, before the aforementioned SSTA spatial patterns, El Niño events were separated into different types in terms of the onset time of these events. Generally, the onset time of El Niño events is used to classify the El Niño events into spring (SP) and summer (SU) onset types. It is worth getting more understanding.
The ENSO events strongly interact with monsoons. Many studies revealed a close relationship between ENSO and temperature along with precipitation surrounding the tropical Pacific. The monsoon is phase-locked and distinguished by a seasonal change of wind direction which brings wet and dry seasons to the related regions. ENSO is also characterized by a phase-locked relationship to mature in boreal winter. However, a lot of questions related to the ENSO issue are far from clearly being understood. With more observations and a new generation of climate model simulations used in this field, increased understanding is necessary.
For this purpose, we solicit high quality, original research contributions from data analysis, theory investigation and model simulation to enhance understanding about the ENSO events.
· The uncertainties for the ENSO patterns based on analysis of the different data sets and the different approaches
· The impacts of the decadal climate changes or the global warming on the ENSO variabilities
· The performance of the current climate model, such as CMIP3 or CMIP5, in the simulation of the ENSO
· New viewpoints of potential mechanisms responsible for the occurrence of the ENSO events
· The predictability of ENSO events
· The relationship between the ENSO and the global monsoons
· The possible impacts of ENSO on climate and weather extreme events
· The possible connection between ENSO and the other climate systems, such as PDO, sea ice, etc.
Manuscript Due: July 31, 2016
First Round of Reviews: October 31, 2016
Publication Date: December 31, 2016
More information about the journal: http://explore.tandfonline.com/cfp/est/aosl