scholarly journals Distinct Evolution of Sea Surface Temperature over the Cold Tongue Region in South China Sea during Various El Niño Events

Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1689
Author(s):  
Min Wu ◽  
Li Qi
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
El Niño ◽  
El Nino ◽  
Sea Surface ◽  
Cold Tongue ◽  
Cp El Niño ◽  
El Niño Events ◽  
Sst Anomaly ◽  
El Nino Events

This study investigates the evolution of the sea surface temperature (SST) over the cold tongue (CT) region in the central South China Sea (SCS) during various El Niño events. A significant and distinct double-peak warming evolution can occur during EP El Niño and CP El Niño events, with the former being more remarkable and robust than the latter. Further analyses show that the weak and insignificant CT SST anomaly in CP El Niño events is influenced by some CP El Niño events in which the warm sea surface temperature anomaly (SSTA) is located west of 175° E (WCP El Niño). The response of CT SSTA mainly depends on the warm SSTA location of CP El Niño. The different corresponding mechanisms in winter, spring and summer are discussed respectively in this work. Further analysis reveals that the weak and insignificant SST anomaly over the CT region in CP El Niño events is caused by the faint SSTA response during the WCP El Niño events. The results of this study call attention to the response of the SCS climate in both atmosphere and ocean to the diversity of ENSO, especially the CP El Niño.

Influences of ENSO Teleconnection on the Persistence of Sea Surface Temperature in the Tropical Indian Ocean

2012 ◽  
Vol 25 (23) ◽  
pp. 8177-8195 ◽  
Author(s):  
Ruiqiang Ding ◽  
Jianping Li
Keyword(s):  
Indian Ocean ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
El Niño ◽  
El Nino ◽  
Tropical Indian Ocean ◽  
Sea Surface ◽  
Sign Reversal ◽  
El Niño Events ◽  
El Nino Events

Abstract This study confirms a weak spring persistence barrier (SPB) of sea surface temperature anomalies (SSTAs) in the western tropical Indian Ocean (WIO), a strong fall persistence barrier (FPB) in the South China Sea (SCS), and the strongest winter persistence barrier (WPB) in the southeastern tropical Indian Ocean (SEIO). During El Niño events, a less abrupt sign reversal of SSTAs occurs in the WIO during spring, an abrupt reversal occurs in the SCS during fall, and the most abrupt reversal occurs in the SEIO during winter. The sign reversal of SSTA implies a rapid decrease in SSTA persistence, which is favorable for the occurrence of a persistence barrier. The present results indicate that a more abrupt reversal of SSTA sign generally corresponds to a more prominent persistence barrier. El Niño–induced changes in atmospheric circulation result in reduced evaporation and suppressed convection. This in turn leads to the warming over much of the TIO basin, which is an important mechanism for the abrupt switch in SSTA, from negative to positive, in the northern SCS and SEIO. The seasonal cycle of the prevailing surface winds has a strong influence on the timing of the persistence barriers in the TIO. The Indian Ocean dipole (IOD) alone can cause a weak WPB in the SEIO. El Niño events co-occurring with positive IOD further strengthen the SEIO WPB. The SEIO WPB appears to be more strongly influenced by ENSO than by the IOD. In contrast, the WIO SPB and the SCS FPB are relatively independent of the IOD.

scholarly journals Mean sea surface temperature changes influence ENSO-related precipitation changes in the mid-latitudes

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Young-Min Yang ◽  
Jae-Heung Park ◽  
Soon-Il An ◽  
Bin Wang ◽  
Xiao Luo
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
El Niño ◽  
El Nino ◽  
Sea Surface ◽  
Future Global Warming ◽  
Mean Sea Surface ◽  
El Niño Events ◽  
Precipitation Changes ◽  
El Nino Events

AbstractEl Niño profoundly impacts precipitation in high-population regions. This demands an advanced understanding of the changes in El Niño-induced precipitation under the future global warming scenario. However, thus far, consensus is lacking regarding future changes in mid-latitude precipitation influenced by El Niño. Here, by analyzing the Coupled Model Intercomparison Project simulations, we show that future precipitation changes are tightly linked to the response of each type of El Niño to the tropical Pacific mean sea surface temperature (SST) change. A La Niña-like mean SST change intensifies basin-wide El Niño events causing approximately 20% more precipitation over East Asia and North America via enhancing moisture transport. Meanwhile, an El Niño-like mean SST change generates more frequent eastern Pacific El Niño events, enhancing precipitation in North American. Our findings highlight the importance of the mean SST projection in selectively influencing the types of El Niño and their remote impact on precipitation.

scholarly journals New Indices for Better Understanding ENSO by Incorporating Convection Sensitivity to Sea Surface Temperature

2020 ◽  
Vol 33 (16) ◽  
pp. 7045-7061 ◽  
Author(s):  
Ruihuang Xie ◽  
Mu Mu ◽  
Xianghui Fang
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
El Niño ◽  
El Nino ◽  
Longwave Radiation ◽  
High Impact ◽  
Sea Surface ◽  
Eastern Pacific ◽  
El Niño Events ◽  
El Nino Events

AbstractObserved outgoing longwave radiation (OLR) data indicate that convection is nonlinearly sensitive to sea surface temperature anomalies (SSTA) for background SSTs in the 25.25°–30.25°C high-impact range. In this study, we use that observed convection sensitivity to derive a proxy of the convective responses to SSTA only [referred to as fluctuations of the accumulated convection strength (FACT)]. FACT reproduces the pattern of the observed convection response to ENSO in the central and eastern Pacific, but underestimates the amplitude due to the exclusion of the effect of ENSO-induced atmospheric convergence anomalies on convection. We thus use FACT to define new indices (InFACT) of ENSO diversity that explicitly account for the nonlinear convection–SST sensitivity. The amplitude of InFACT allows us to easily classify El Niño events into weak, moderate, and strong types that markedly differ in terms of SSTA spatial patterns and their convective responses. La Niña events classified by InFACT display much less pattern diversity, and mostly differ through their amplitudes. Finally, our study supports some previous studies that the nonlinear SST–convection relation plays a strong role for the development of extreme El Niño events with the presence of high-impact SSTs and large convection anomalies in the equatorial eastern Pacific.

scholarly journals ANALISIS KEJADIAN EL NINO DAN PENGARUHNYA TERHADAP INTENSITAS CURAH HUJAN DI WILAYAH JABODETABEK (Studi Kasus : Periode Puncak Musim Hujan Tahun 2015/2016)

2016 ◽  
Vol 17 (2) ◽  
pp. 65
Author(s):  
Ardila Yananto ◽  
Rini Mariana Sibarani
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
El Niño ◽  
Southern Oscillation Index ◽  
El Nino ◽  
Southern Oscillation ◽  
Tropical Rainfall Measuring Mission ◽  
Sea Surface ◽  
El Niño Events ◽  
El Nino Events

IntisariBeberapa lembaga riset dunia dan badan-badan meteorologi beberapa negara di dunia menyatakan adanya kejadian El Nino Tahun 2015 terus berlanjut hingga tahun 2016. Adanya kejadian El Nino tersebut secara umum akan mempengarui intensitas curah hujan di sebagian besar wilayah Indonesia termasuk wilayah Jabodetabek. Analisis kejadian El Nino Tahun 2015/2016 dilakukan dengan menganalisis nilai NINO 3.4 SST Index, Southern Oscillation Index (SOI), Indian Ocean Dipole (IOD), pola sebaran suhu permukaan laut (Sea Surface Temperature) dan juga gradient wind di Samudra Pasifik Tropis. Sedangkan Analisis Curah Hujan dilakukan dengan menggunakan data TRMM (Tropical Rainfall Measuring Mission). Dari penelitian ini dapat diketahui bahwa berdasarkan parameter NINO 3.4 SST Index dan Southern Oscillation Index (SOI) pada pertengahan Tahun 2015 hingga awal Tahun 2016 telah terjadi fenomana El Nino pada level kuat, adanya peningkatan suhu permukaan laut di sebagian besar wilayah Indonesia sejak Bulan November 2015 yang diikuti dengan penurunan indeks Dipole Mode hingga menjadi bernilai negatif (-) sejak awal Tahun 2016 serta dengan adanya peralihan Angin Muson Timur ke Angin Muson Barat di wilayah Indonesia telah menyebabkan peningkatan curah hujan yang cukup signifikan dalam batas normal di wilayah Jabodetabek pada puncak musim hujan Tahun 2015/2016 (November 2015 - Februari 2016) walaupun pada Bulan November 2015 hingga Februari 2016 tersebut masih berada pada level El Nino kuat.   AbstractVarious research institutions in the world that work in the field of Meteorology and Climatology predicted an El Nino events in 2015 continued into 2016. The El Nino events phenomenon in general will affect to intensity of the rainfall in most parts of Indonesia, including the Greater Jakarta area. El Nino events phenomenon Analysis by Nino 3.4 SST index, Southern Oscillation Index (SOI), Indian Ocean Dipole (IOD), Sea Surface Temperature (SST) and gradient wind in the Tropical Pacific Ocean. While rainfall intensity analysis using TRMM (Tropical Rainfall Measuring Mission) data. From this research it is known that based on the parameters NINO 3.4 SST index and the Southern Oscillation Index (SOI), it is known that there was a strong El Nino event occurred in mid-2015 to early 2016, the increase of sea surface temperature in most parts of Indonesia since November 2015 followed by declines Dipole Mode Index to be negative (-) since the beginning 2016 as well as the shift East monsoon to West monsoon in Indonesia has led to significant rainfall increased within normal limits in the Greater Jakarta area at the peak period of the rainy season 2015/2016 (November 2015 - February 2016) although in November 2015 until February 2016 El Nino event is still at the strong level.  

Two Types of El Niño Events: Cold Tongue El Niño and Warm Pool El Niño

2009 ◽  
Vol 22 (6) ◽  
pp. 1499-1515 ◽  
Author(s):  
Jong-Seong Kug ◽  
Fei-Fei Jin ◽  
Soon-Il An
Keyword(s):  
Spatial Patterns ◽  
El Niño ◽  
El Nino ◽  
Warm Pool ◽  
Discharge Process ◽  
Cold Tongue ◽  
El Niño Events ◽  
Sst Anomaly ◽  
Sst Anomalies ◽  
El Nino Events

Abstract In this study, two types of El Niño events are classified based on spatial patterns of the sea surface temperature (SST) anomaly. One is the cold tongue (CT) El Niño, which can be regarded as the conventional El Niño, and the other the warm pool (WP) El Niño. The CT El Niño is characterized by relatively large SST anomalies in the Niño-3 region (5°S–5°N, 150°–90°W), while the WP El Niño is associated with SST anomalies mostly confined to the Niño-4 region (5°S–5°N, 160°E–150°W). In addition, spatial patterns of many atmospheric and oceanic variables are also distinctively different for the two types of El Niño events. Furthermore, the difference in the transition mechanism between the two types of El Niño is clearly identified. That is, the discharge process of the equatorial heat content associated with the WP El Niño is not efficient owing to the spatial structure of SST anomaly; as a result, it cannot trigger a cold event. It is also demonstrated that zonal advective feedback (i.e., zonal advection of mean SST by anomalous zonal currents) plays a crucial role in the development of a decaying SST anomaly associated with the WP El Niño, while thermocline feedback is a key process during the CT El Niño.

scholarly journals A Verified Estimation of the El Niño Index Niño-3.4 since 1877

2009 ◽  
Vol 22 (14) ◽  
pp. 3979-3992 ◽  
Author(s):  
Lucia Bunge ◽  
Allan J. Clarke
Keyword(s):  
Time Series ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Correlation Coefficients ◽  
Sea Surface ◽  
Monthly Time Series ◽  
Sst Anomaly

Abstract Decadal and longer time-scale variabilities of the best known El Niño–Southern Oscillation (ENSO) indexes are poorly correlated before 1950, and so knowledge of interdecadal variability and trend in ENSO indexes is dubious, especially before 1950. To address this problem, the authors constructed and compared physically related monthly ENSO indexes. The base index was El Niño index Niño-3.4, the sea surface temperature (SST) anomaly averaged over the equatorial box bounded by 5°N, 5°S, 170°W, and 120°W; the authors also constructed indexes based on the nighttime marine air temperature over the Niño-3.4 region (NMAT3.4) and an equatorial Southern Oscillation index (ESOI). The Niño-3.4 index used the “uninterpolated” sea surface temperature data from the Second Hadley Centre Sea Surface Temperature dataset (HadSST2), a dataset with smaller uncertainty and better geographical coverage than others. In constructing the index, data at each point for a given month were weighted to take into account the typical considerable spatial variation of the SST anomaly over the Niño-3.4 box as well as the number of observations at that point for that month. Missing monthly data were interpolated and “noise” was reduced by using the result that Niño-3.4 has essentially the same calendar month amplitude structure every year. This 12-point calendar month structure from April to March was obtained by an EOF analysis over the last 58 yr and then was fitted to the entire monthly time series using a least squares approach. Equivalent procedures were followed for NMAT3.4 and ESOI. The new ESOI uses Darwin atmospheric pressure in the west and is based on theory that allows for variations of the atmospheric boundary layer depth across the Pacific. The new Niño-3.4 index was compared with NMAT3.4, the new ESOI, and with a record of δ18O from a coral at Palmyra, an atoll inside the region Niño-3.4 (Cobb et al.). Correlation coefficients between Niño-3.4 and the three monthly indexes mentioned above before 1950 are 0.84, 0.87, 0.73 and 0.93, 0.86, 0.73 for decadal time scales. These relatively high correlation coefficients between physically related but independent monthly time series suggest that this study has improved knowledge of low-frequency variability. All four indexes are consistent with a rise in Niño-3.4 SST and the weakening of the equatorial Pacific winds since about 1970.

scholarly journals The influence of interannual and decadal Indo-Pacific sea surface temperature variability on Australian monsoon rainfall

2021 ◽  
pp. 1-58
Author(s):  
Hanna Heidemann ◽  
Joachim Ribbe ◽  
Tim Cowan ◽  
Benjamin J. Henley ◽  
Christa Pudmenzky ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
El Niño ◽  
El Nino ◽  
La Niña ◽  
Sea Surface ◽  
Northern Australia ◽  
Central Pacific ◽  
Cp El Niño ◽  
La Nina

AbstractMonsoonal rainfall varies substantially in Northern Australia (AUMR) on interannual, decadal and longer time scales, profoundly impacting natural systems and agricultural communities. Some of this variability arises in response to sea surface temperature (SST) variability in the Indo-Pacific linked to both the El Niño-Southern Oscillation (ENSO) and the Interdecadal Pacific Oscillation (IPO). Here we use observations to investigate unresolved issues regarding the influence of the IPO and ENSO on AUMR. Specifically, we show that during negative IPO phases, central Pacific (CP) El Niño events are associated with below average rainfall over northeast Australia, an anomalous anticyclonic pattern to the northwest of Australia, and eastward moisture advection towards the Dateline. In contrast, CP La Niña events (distinct from eastern Pacific La Niña events) during negative IPO phases drive significantly wet conditions over much of northern Australia, a strengthened Walker Circulation, and large-scale moisture flux convergence. During positive IPO phases, the impact of CP El Niño and CP La Niña events on AUMR is weaker. The influence of central Pacific SSTs on AUMR has been stronger during the recent (post-1999) negative IPO phase. The extent to which this strengthening is associated with climate change or merely natural, internal variability is not known.

The Contribution of Indian Ocean Sea Surface Temperature Anomalies on Australian Summer Rainfall during El Niño Events

2011 ◽  
Vol 24 (14) ◽  
pp. 3734-3747 ◽  
Author(s):  
Andréa S. Taschetto ◽  
Alex Sen Gupta ◽  
Harry H. Hendon ◽  
Caroline C. Ummenhofer ◽  
Matthew H. England
Keyword(s):  
Indian Ocean ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Atmospheric Circulation ◽  
Southern Hemisphere ◽  
El Niño ◽  
El Nino ◽  
Sea Surface ◽  
El Niño Events ◽  
The Indian Ocean

Abstract This study investigates the impact of Indian Ocean sea surface temperature (SST) anomalies on the atmospheric circulation of the Southern Hemisphere during El Niño events, with a focus on Australian climate. During El Niño episodes, the tropical Indian Ocean exhibits two types of SST response: a uniform “basinwide warming” and a dipole mode—the Indian Ocean dipole (IOD). While the impacts of the IOD on climate have been extensively studied, the effects of the basinwide warming, particularly in the Southern Hemisphere, have received less attention. The interannual basinwide warming response has important implications for Southern Hemisphere atmospheric circulation because 1) it accounts for a greater portion of the Indian Ocean monthly SST variance than the IOD pattern and 2) its maximum amplitude occurs during austral summer to early autumn, when large parts of Australia, South America, and Africa experience their monsoon. Using observations and numerical experiments with an atmospheric general circulation model forced with historical SST from 1949 to 2005 over different tropical domains, the authors show that the basinwide warming leads to a Gill–Matsuno-type response that reinforces the anomalies caused by changes in the Pacific as part of El Niño. In particular, the basinwide warming drives strong subsidence over Australia, prolonging the dry conditions during January–March, when El Niño–related SST starts to decay. In addition to the anomalous circulation in the tropics, the basinwide warming excites a pair of barotropic anomalies in the Indian Ocean extratropics that induces an anomalous anticyclone in the Great Australian Bight.

The Initiation and Developing Mechanisms of Central Pacific El Niños

2014 ◽  
Vol 27 (12) ◽  
pp. 4473-4485 ◽  
Author(s):  
Jingzhi Su ◽  
Tim Li ◽  
Renhe Zhang
Keyword(s):  
El Niño ◽  
El Nino ◽  
Ocean Dynamics ◽  
Central Pacific ◽  
Cp El Niño ◽  
Thermocline Feedback ◽  
El Niño Events ◽  
Sst Warming ◽  
Sst Anomaly ◽  
El Nino Events

Abstract The initiation and developing mechanisms of four major central Pacific (CP) El Niño events in 1994, 2002, 2004, and 2009 were investigated by analyzing oceanic and atmospheric reanalysis data. A mixed layer heat budget analysis was conducted and the result shows that the initiation mechanism of the 1994 CP El Niño is very different from other CP El Niños in 2000s, while the developing mechanisms are similar among these events. The initial sea surface temperature (SST) warming of the 1994 El Niño was caused by enhanced solar radiation, which was related to atmospheric meridional overturning circulation in association with positive SST anomaly forcing in the subtropical Pacific. The subtropical SST anomalies also induced anticyclonic surface wind stress curl anomalies, which caused the formation of subsurface warmer waters in the off-equatorial regions. The off-equatorial subsurface warmer waters were transported farther equatorward by the mean subsurface ocean currents, leading to the subsurface warming in the central equatorial Pacific. The deepened thermocline anomaly at the equator further promoted a positive advective and thermocline feedback so that the SST anomaly grew. During the initiation phase of the 2000s El Niños, ocean dynamics played a dominant role, while the effect of surface heat flux anomalies was minor. Preexisting subsurface warmer waters appeared in the equatorial region during their initiation phases. Such subsurface anomalies can cause the SST warming in the central Pacific through induced anomalous eastward zonal currents that advect high mean SST eastward. This positive zonal advective feedback, along with a positive thermocline feedback, continued to warm the local SST throughout the developing phase of the 2000s El Niño events.

scholarly journals Time-Spatial Features of Mix El Niño

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 476
Author(s):  
Zhiyuan Zhang ◽  
Gen Li
Keyword(s):  
El Niño ◽  
El Nino ◽  
Sea Surface ◽  
Eastern Pacific ◽  
Central Pacific ◽  
Cp El Niño ◽  
Spatial Features ◽  
El Niño Events ◽  
Far Eastern ◽  
El Nino Events

The diversity of El Niño is a critical field of the climate research. The eastern Pacific (EP) and central Pacific (CP) types of El Niño have been identified in the previous studies. However, the extreme El Niño event that occurred in 2015–2016 is quite different from both the EP and CP El Niño events. The sea surface temperatures anomalies (SSTA) for this event widely spread in both the central and eastern Pacific and have a small zonal gradient in the central-eastern Pacific. Many researchers regarded this event as a mixed type of El Niño. Using the regression-EOF method, the Mix El Niño pattern is extracted from the tropical Pacific SSTA field during the period from 1900 to 2019. Here, we reveal that the Mix El Niño is a very usual rather than a new type of El Niño, it is just that the EP and CP El Niño events are more frequent since the 1980s, while the Mix El Niño events frequently appear before the 1980s. The time-spatial features of the Mix El Niño are further investigated. The results demonstrate a unique westward propagation of the maximum SSTA for the Mix El Niño from the far eastern Pacific to the central Pacific. In contrast, the SSTA center is locked in the far eastern Pacific region for the EP El Niño and the central Pacific region for the CP El Niño. The evolutions of subsurface ocean temperature anomalies and sea surface height anomalies are also examined to support this. The ocean–atmosphere interaction plays an important role in the evolution of the Mix El Niño. The anomalous atmospheric Walker circulation for the Mix El Niño is mainly in the western and central Pacific as well as very weak in the eastern Pacific. In contrast, there are significant westerlies/easterlies in the eastern Pacific for the EP/CP El Niño. The small gradient of SSTA in the central-eastern Pacific for the Mix El Niño leads to weak zonal wind anomalies, which further weaken the zonal gradient of SSTA. All this suggests that the Mix El Niño is not unusual and fundamentally different from the EP and CP El Niño with important implications for global climate effects.

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