El Nino and interannual variation of the sea surface temperature in the tropical Indian Ocean

2003 ◽  
Author(s):  
Renhe Zhang ◽  
Yanke Tan
2012 ◽  
Vol 25 (23) ◽  
pp. 8177-8195 ◽  
Author(s):  
Ruiqiang Ding ◽  
Jianping Li

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.


2020 ◽  
Vol 33 (2) ◽  
pp. 727-747
Author(s):  
Chunxiang Li ◽  
Chunzai Wang ◽  
Tianbao Zhao

AbstractSeasonal covariability of the dryness/wetness in China and global sea surface temperature (SST) is investigated by using the monthly self-calibrated Palmer drought severity index (PDSI) data and other data from 1950 to 2014. The singular value decomposition (SVD) analysis shows two recurring PDSI–SST coupled modes. The first SVD mode of PDSI is associated with the warm phases of the eastern Pacific–type El Niño–Southern Oscillation (ENSO), the interdecadal Pacific oscillation (IPO) or Pacific decadal oscillation (PDO), the Indian Ocean basin mode (IOBM) in the autumn and winter, and the cold phase of the IOBM in the spring. Meanwhile, the Atlantic multidecadal oscillation (AMO) pattern appears in every season except the autumn. The second SVD mode of PDSI is accompanied by a central Pacific–type El Niño developing from the winter to autumn over the tropical Pacific and a positive phase of IPO or PDO from the winter to summer. Moreover, an AMO pattern is observed in all seasons except the summer, whereas the SST over the tropical Indian Ocean shows negligible variations. The further analyses suggest that AMO remote forcing may be a primary factor influencing interdecadal variability of PDSI in China, and interannual to interdecadal variability of PDSI seems to be closely associated with the ENSO-related events. Meanwhile, the IOBM may be a crucial factor in interannual variability of PDSI during its mature phase in the spring. In general, the SST-related dryness/wetness anomalies can be explained by the associated atmospheric circulation changes.


2007 ◽  
Vol 20 (13) ◽  
pp. 2872-2880 ◽  
Author(s):  
Gary Meyers ◽  
Peter McIntosh ◽  
Lidia Pigot ◽  
Mike Pook

Abstract The Indian Ocean zonal dipole is a mode of variability in sea surface temperature that seriously affects the climate of many nations around the Indian Ocean rim, as well as the global climate system. It has been the subject of increasing research, and sometimes of scientific debate concerning its existence/nonexistence and dependence/independence on/from the El Niño–Southern Oscillation, since it was first clearly identified in Nature in 1999. Much of the debate occurred because people did not agree on what years are the El Niño or La Niña years, not to mention the newly defined years of the positive or negative dipole. A method that identifies when the positive or negative extrema of the El Niño–Southern Oscillation and Indian Ocean dipole occur is proposed, and this method is used to classify each year from 1876 to 1999. The method is statistical in nature, but has a strong basis on the oceanic physical mechanisms that control the variability of the near-equatorial Indo-Pacific basin. Early in the study it was found that some years could not be clearly classified due to strong decadal variation; these years also must be recognized, along with the reason for their ambiguity. The sensitivity of the classification of years is tested by calculating composite maps of the Indo-Pacific sea surface temperature anomaly and the probability of below median Australian rainfall for different categories of the El Niño–Indian Ocean relationship.


2014 ◽  
Vol 27 (22) ◽  
pp. 8413-8421 ◽  
Author(s):  
Lei Zhang ◽  
Tim Li

Abstract How sea surface temperature (SST) changes under global warming is critical for future climate projection because SST change affects atmospheric circulation and rainfall. Robust features derived from 17 models of phase 5 of the Coupled Model Intercomparison Project (CMIP5) include a much greater warming in high latitudes than in the tropics, an El Niño–like warming over the tropical Pacific and Atlantic, and a dipole pattern in the Indian Ocean. However, the physical mechanism responsible for formation of such warming patterns remains open. A simple theoretical model is constructed to reveal the cause of the future warming patterns. The result shows that a much greater polar, rather than tropical, warming depends primarily on present-day mean SST and surface latent heat flux fields, and atmospheric longwave radiation feedback associated with cloud change further enhances this warming contrast. In the tropics, an El Niño–like warming over the Pacific and Atlantic arises from a similar process, while cloud feedback resulting from different cloud regimes between east and west ocean basins also plays a role. A dipole warming over the equatorial Indian Ocean is a response to weakened Walker circulation in the tropical Pacific.


2016 ◽  
Author(s):  
J. Zinke ◽  
L. Reuning ◽  
M. Pfeiffer ◽  
J. Wassenburg ◽  
E. Hardman ◽  
...  

Abstract. The western Indian Ocean has been warming rapidly over the past decades and this has adversely impacted the Asian Monsoon circulation. It is therefore of paramount importance to improve our understanding of links between Indian Ocean Sea Surface Temperature (SST) variability, climate change, and sustainability of reef ecosystems. Here we present two monthly-resolved coral Sr/Ca records (Totor, Cabri) from Rodrigues Island (63° E, 19° S) in the south-central Indian Ocean trade wind belt, and reconstruct SST based on the linear relationship with the Sr/Ca proxy. The records extend to 1781 and 1945, respectively. We assess the reproducibility of the Sr/Ca records, and potential biases in our reconstruction associated with the orientation of corallites. We quantify long-term SST trends and identify interannual relationships with the El Niño-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). We conclude that careful screening for diagenesis and orientation of corallites is of paramount importance to assess the quality of Sr/Ca-based SST reconstructions. Our proxy records provide a reliable SST reconstruction between 1945 and 2006. We identify strong teleconnections with the ENSO/PDO over the past 60 years, eg. warming of SST during El Niño or positive PDO. We suggest that additional records from Rodrigues Island can provide excellent records of SST variations in the southern Indian Ocean trade wind belt and teleconnections with the ENSO/PDO on longer time scales.


2005 ◽  
Vol 18 (10) ◽  
pp. 1449-1468 ◽  
Author(s):  
Wenju Cai ◽  
Harry H. Hendon ◽  
Gary Meyers

Abstract Coupled ocean–atmosphere variability in the tropical Indian Ocean is explored with a multicentury integration of the Commonwealth Scientific and Industrial Research Organisation (CSIRO) Mark 3 climate model, which runs without flux adjustment. Despite the presence of some common deficiencies in this type of coupled model, zonal dipolelike variability is produced. During July through November, the dominant mode of variability of sea surface temperature resembles the observed zonal dipole and has out-of-phase rainfall variations across the Indian Ocean basin, which are as large as those associated with the model El Niño–Southern Oscillation (ENSO). In the positive dipole phase, cold SST anomaly and suppressed rainfall south of the equator on the Sumatra–Java coast drives an anticyclonic circulation anomaly that is consistent with the steady response (Gill model) to a heat sink displaced south of the equator. The northwest–southeast tilting Sumatra–Java coast results in cold sea surface temperature (SST) centered south of the equator, which forces anticylonic winds that are southeasterly along the coast, which thus produces local upwelling, cool SSTs, and promotes more anticylonic winds; on the equator, the easterlies raise the thermocline to the east via upwelling Kelvin waves and deepen the off-equatorial thermocline to the west via off-equatorial downwelling Rossby waves. The model dipole mode exhibits little contemporaneous relationship with the model ENSO; however, this does not imply that it is independent of ENSO. The model dipole often (but not always) develops in the year following El Niño. It is triggered by an unrealistic transmission of the model’s ENSO discharge phase through the Indonesian passages. In the model, the ENSO discharge Rossby waves arrive at the Sumatra–Java coast some 6 to 9 months after an El Niño peaks, causing the majority of model dipole events to peak in the year after an ENSO warm event. In the observed ENSO discharge, Rossby waves arrive at the Australian northwest coast. Thus the model Indian Ocean dipolelike variability is triggered by an unrealistic mechanism. The result highlights the importance of properly representing the transmission of Pacific Rossby waves and Indonesian throughflow in the complex topography of the Indonesian region in coupled climate models.


2005 ◽  
Vol 18 (9) ◽  
pp. 1351-1368 ◽  
Author(s):  
Pascal Terray ◽  
Sébastien Dominiak

Abstract Here the 1976–77 climate regime shift that was accompanied by a remarkable change in the lead–lag relationships between Indian Ocean sea surface temperature (SST) and El Niño evolution is shown. After the 1976–77 regime shift, a correlation analysis suggests that southern Indian Ocean SSTs observed during late boreal winter are a key precursor in predicting El Niño evolution as the traditional oceanic heat content anomalies in the equatorial Pacific or zonal wind anomalies over the equatorial western Pacific. The possible physical mechanisms underlying this highly significant statistical relationship are discussed. After the 1976–77 regime shift, southern Indian Ocean SST anomalies produced by Mascarene high pulses during boreal winter trigger coupled air–sea processes in the tropical eastern Indian Ocean during the following seasons. This produces a persistent remote forcing on the Pacific climate system, promoting wind anomalies over the western equatorial Pacific and modulating the regional Hadley cell in the southwest Pacific. These modulations, in turn, excite Rossby waves, which produce quasi-stationary circulation anomalies in the extratropical South Pacific, responsible for the development of the southern branch of the “horseshoe” El Niño pattern. The change of the background SST state that occurred in the late 1970s over the Indian Ocean may also explain why ENSO evolution is different before and after the 1976–77 regime shift. These results shed some light on the possible influence of global warming or decadal fluctuations on El Niño evolution through changes in teleconnection patterns between the Indian and Pacific Oceans.


2011 ◽  
Vol 24 (14) ◽  
pp. 3734-3747 ◽  
Author(s):  
Andréa S. Taschetto ◽  
Alex Sen Gupta ◽  
Harry H. Hendon ◽  
Caroline C. Ummenhofer ◽  
Matthew H. England

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.


Author(s):  
Candra Saputra ◽  
I Wayan Arthana ◽  
I Gede Hendrawan

The aim of this research is to know the relationship between lemuru fish catch to Sea Surface Temperature (SST), El-Nino Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) phenomenon in Bali Strait. The results showed, that in the period 2007 – 2016. fluctuations of catches lemuru tends to decline. Sea Surface Temperature (SST) distribution with the lowest temperature 25,28oC at 24,53oC - 27,16oC and the highest temperature is 29,31oC in the range of 28,730C – 30,490C. The lowest temperature occurred in July - September while the highest temperature occurred in January - April. Based on the calculation there is a linkage and relationship between catch and SST as shown on the value of determination and correlation reached 50,0% and 70,73%. Most of the catches occurred in the west season and then the transition II, transition I and East Season. The relationship of ENSO phenomenon to the catch during the El-Nino phase of lemuru catch will increase while in the phase of La-Nina the catch of lemuru will decrease, because time of El-Nino phase of the sea surface temperature (SST) relative low which results in the chlorophyll-a mean case which is a food sources of lemuru fish. Based on Trenberth's theory, (1997), the rise and fall of the ENSO Index of less than six months is not stated in ENSO. From the calculation results during the research of 2007 - 2016 happened three times ENSO phenomenon that is in 2009, 2010 and 2015. At the time of the IOD phenomenon, the IOD (+) phase will result in a decrease in catch while the normal IOD phase and (-) will increase the catch. From the results of this study can also be observed, in the year 2007 - 2011 phenomenon ENSO and IOD have a strong influence on the catch while in the year 2012 - 2016 the influence of the phenomenon of ENSO and IOD has no strong influence caused by the quantity of lemuru fish that have been over exploitation that resulted in the current Bali Strait on Over Fishing status.   Keywords : Fish Catch; El-Nino Southern Oscillation (ENSO); Indian Ocean                    Dipole (IOD)


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