scholarly journals Rainfall Teleconnections with Indo-Pacific Variability in the WCRP CMIP3 Models

2009 ◽  
Vol 22 (19) ◽  
pp. 5046-5071 ◽  
Author(s):  
Wenju Cai ◽  
Arnold Sullivan ◽  
Tim Cowan
Keyword(s):  
Indian Ocean ◽  
Climate Models ◽  
Southern Oscillation ◽  
Equatorial Pacific ◽  
Boreal Winter ◽  
Small Subset ◽  
Stochastic Noise ◽  
Cold Tongue ◽  
Eastern Equatorial Pacific ◽  
The Indian Ocean

Abstract The present study assesses the ability of climate models to simulate rainfall teleconnections with the El Niño–Southern Oscillation (ENSO) and the Indian Ocean dipole (IOD). An assessment is provided on 24 climate models that constitute phase 3 of the World Climate Research Programme’s Coupled Model Intercomparison Project (WCRP CMIP3), used in the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC). The strength of the ENSO–rainfall teleconnection, defined as the correlation between rainfall and Niño-3.4, is overwhelmingly controlled by the amplitude of ENSO signals relative to stochastic noise, highlighting the importance of realistically simulating this parameter. Because ENSO influences arise from the movement of convergence zones from their mean positions, the well-known equatorial Pacific climatological sea surface temperature (SST) and ENSO cold tongue anomaly biases lead to systematic errors. The climatological SSTs, which are far too cold along the Pacific equator, lead to a complete “nonresponse to ENSO” along the central and/or eastern equatorial Pacific in the majority of models. ENSO anomalies are also too equatorially confined and extend too far west, with linkages to a weakness in the teleconnection with Hawaii boreal winter rainfall and an inducement of a teleconnection with rainfall over west Papua New Guinea in austral summer. Another consequence of the ENSO cold tongue bias is that the majority of models produce too strong a coherence between SST anomalies in the west, central, and eastern equatorial Pacific. Consequently, the models’ ability in terms of producing differences in the impacts by ENSO from those by ENSO Modoki is reduced. Similarly, the IOD–rainfall teleconnection strengthens with an intensification of the IOD relative to the stochastic noise. A significant relationship exists between intermodel variations of IOD–ENSO coherence and intermodel variations of the ENSO amplitude in a small subset of models in which the ENSO anomaly structure and ENSO signal transmission to the Indian Ocean are better simulated. However, using all but one model (defined as an outlier) there is no systematic linkage between ENSO amplitude and IOD–ENSO coherence. Indeed, the majority of models produce an ENSO–IOD coherence lower than the observed, supporting the notion that the Indian Ocean has the ability to generate independent variability and that ENSO is not the only trigger of the IOD. Although models with a stronger IOD amplitude and rainfall teleconnection tend to have a greater ENSO amplitude, there is no causal relationship; instead this feature reflects a commensurate strength of the Bjerknes feedback in both the Indian and Pacific Oceans.

scholarly journals Impact of the April–May SAM on Central Pacific Ocean sea temperature over the following three seasons

2021 ◽  
Author(s):  
Ting Liu ◽  
Jianping Li ◽  
Cheng Sun ◽  
Tao Lian ◽  
Yazhou Zhang
Keyword(s):  
Indian Ocean ◽  
Cold Water ◽  
Southern Oscillation ◽  
Equatorial Pacific ◽  
Boreal Winter ◽  
Central Pacific ◽  
Sea Temperature ◽  
Easterly Wind ◽  
The Indian Ocean ◽  
The Impact

AbstractAlthough the impact of the extratropical Pacific signal on the El Niño–Southern Oscillation has attracted increasing concern, the impact of Southern Hemisphere Annular Mode (SAM)-related signals from outside the southern Pacific Basin on the equatorial sea temperature has received less attention. This study explores the lead correlation between the April–May (AM) SAM and central tropical Pacific sea temperature variability over the following three seasons. For the positive AM SAM case, the related simultaneous warm SST anomalies in the southeastern Indian Ocean favor significant regulation of vertical circulation in the Indian Ocean with anomalous ascending motion in the tropics. This can further enhance convection over the Marine Continent, which induces a significant horizontal Kelvin response and regulates the vertical Walker circulation. These two processes both result in the anomalous easterlies east of 130° E in the equatorial Pacific during AM. These easterly anomalies favor oceanic upwelling and eastward propagation of the cold water into the central Pacific. The cold water in turn amplifies the development of the easterly wind and further maintains the cold water into the boreal winter. The results presented here not only provide a possible link between extratropical climate variability in the Indian Ocean and climate variation in the equatorial Pacific, but also shed new light on the short-term prediction of tropical central Pacific sea temperature.

scholarly journals Late Miocene calcareous nannofossil genus <i>Catinaster:</i> taxonomy, evolution and magnetobiochronology

1998 ◽  
Vol 17 (1) ◽  
pp. 71-85 ◽  
Author(s):  
Alyssa Peleo-Alampay ◽  
David Bukry ◽  
Li Liu ◽  
Jeremy R. Young
Keyword(s):  
Indian Ocean ◽  
Gulf Of Mexico ◽  
Systematic Study ◽  
Late Miocene ◽  
Equatorial Pacific ◽  
Calcareous Nannofossil ◽  
New Subspecies ◽  
Eastern Equatorial Pacific ◽  
First Occurrence ◽  
The Indian Ocean

Abstract. A systematic study on the evolution and stratigraphic distribution of the species of Catinaster from several DSDP/ODP sites with magnetostratigraphic records is presented. The evolution of Catinaster from Discoaster is established by documentation of a transitional nannofossil species, Discoaster transitus. Two new subspecies, Catinaster coalitus extensus and Catinaster calyculus rectus are defined which appear to be intermediates in the evolution of Catinaster coalitus coalitus to Catinaster calyculus calyculus. The first occurrence of C. coalitus is shown to be in the lower part of C5n.2n at 10.7–10.9 Ma in the low to mid–latitude Atlantic and Pacific Oceans. The last occurrence of C. coalitus coalitus varies from the upper part of C5n.2n to the lower portion of C4A. Magnetobiostratigraphic evidence suggests that the FO of C. calyculus rectus is diachronous. Catinaster mexicanus occurs in the late Miocene and has been found only in the eastern equatorial Pacific, the Indian Ocean and the Gulf of Mexico.

scholarly journals Interannual Climate Variability over the Tropical Pacific Ocean Induced by the Indian Ocean Dipole through the Indonesian Throughflow

2013 ◽  
Vol 26 (9) ◽  
pp. 2845-2861 ◽  
Author(s):  
Dongliang Yuan ◽  
Hui Zhou ◽  
Xia Zhao
Keyword(s):  
Pacific Ocean ◽  
Indian Ocean ◽  
Tropical Indian Ocean ◽  
Sea Surface Height ◽  
Equatorial Pacific ◽  
Sea Surface ◽  
Indonesian Throughflow ◽  
Cold Tongue ◽  
The Indian Ocean ◽  
Southeastern Tropical Indian Ocean

Abstract The authors’ previous dynamical study has suggested a link between the Indian and Pacific Ocean interannual climate variations through the transport variations of the Indonesian Throughflow. In this study, the consistency of this oceanic channel link with observations is investigated using correlation analyses of observed ocean temperature, sea surface height, and surface wind data. The analyses show significant lag correlations between the sea surface temperature anomalies (SSTA) in the southeastern tropical Indian Ocean in fall and those in the eastern Pacific cold tongue in the following summer through fall seasons, suggesting potential predictability of ENSO events beyond the period of 1 yr. The dynamics of this teleconnection seem not through the atmospheric bridge, because the wind anomalies in the far western equatorial Pacific in fall have insignificant correlations with the cold tongue anomalies at time lags beyond one season. Correlation analyses between the sea surface height anomalies (SSHA) in the southeastern tropical Indian Ocean and those over the Indo-Pacific basin suggest eastward propagation of the upwelling anomalies from the Indian Ocean into the equatorial Pacific Ocean through the Indonesian Seas. Correlations in the subsurface temperature in the equatorial vertical section of the Pacific Ocean confirm the propagation. In spite of the limitation of the short time series of observations available, the study seems to suggest that the ocean channel connection between the two basins is important for the evolution and predictability of ENSO.

On the relationship between Indian Ocean Dipole, Indian summer monsoon and ENSO

2021 ◽  
Author(s):  
Annalisa Cherchi ◽  
Pascal Terray ◽  
Satyaban Bishoyi Ratna ◽  
Virna Meccia ◽  
Sooraj K.P.
Keyword(s):  
Indian Ocean ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Indian Ocean Dipole ◽  
Climate Models ◽  
Southern Oscillation ◽  
Global Climate ◽  
Global Climate Models ◽  
The Future ◽  
The Indian Ocean

&lt;p&gt;The Indian Ocean Dipole (IOD) is one of the dominant modes of variability of the tropical Indian Ocean and it has been suggested to have a crucial role in the teleconnection between the Indian summer monsoon and El Nino Southern Oscillation (ENSO). The main ideas at the base of the influence of the IOD on the ENSO-monsoon teleconnection include the possibility that it may strengthen summer rainfall over India, as well as the opposite, and also that it may produce a remote forcing on ENSO itself. The Indian Ocean has been experiencing a warming, larger than any other basins, since the 1950s. During these decades, the summer monsoon rainfall over India decreased and the frequency of Indian Ocean Dipole (IOD) events increased. In the future the IOD is projected to further increase in frequency and amplitude with mean conditions mimicking the characteristics of its positive phase. Still, state of the art global climate models have large biases in representing IOD and monsoon mean state and variability, with potential consequences for properties and related teleconnections projected in the future. This works collects a review study of the influence of the IOD on the ISM and its relationship with ENSO, as well as new results on IOD projections comparing CMIP5 and CMIP6 models.&lt;/p&gt;

scholarly journals Compound high-temperature and low-chlorophyll extremes in the ocean over the satellite period

2021 ◽  
Vol 18 (6) ◽  
pp. 2119-2137
Author(s):  
Natacha Le Grix ◽  
Jakob Zscheischler ◽  
Charlotte Laufkötter ◽  
Cecile S. Rousseaux ◽  
Thomas L. Frölicher
Keyword(s):  
High Temperature ◽  
Indian Ocean ◽  
Extreme Events ◽  
Large Scale ◽  
Southern Oscillation ◽  
Chlorophyll Concentration ◽  
Equatorial Pacific ◽  
Compound Event ◽  
Eastern Equatorial Pacific ◽  
Compound Events

Abstract. Extreme events in the ocean severely impact marine organisms and ecosystems. Of particular concern are compound events, i.e., when conditions are extreme for multiple potential ocean ecosystem stressors such as temperature and chlorophyll. Yet, little is known about the occurrence, intensity, and duration of such compound high-temperature (a.k.a. marine heatwaves – MHWs) and low-chlorophyll (LChl) extreme events, whether their distributions have changed in the past decades, and what the potential drivers are. Here we use satellite-based sea surface temperature and chlorophyll concentration estimates to provide a first assessment of such compound extreme events. We reveal hotspots of compound MHW and LChl events in the equatorial Pacific, along the boundaries of the subtropical gyres, in the northern Indian Ocean, and around Antarctica. In these regions, compound events that typically last 1 week occur 3 to 7 times more often than expected under the assumption of independence between MHWs and LChl events. The occurrence of compound MHW and LChl events varies on seasonal to interannual timescales. At the seasonal timescale, most compound events occur in summer in both hemispheres. At the interannual timescale, the frequency of compound MHW and LChl events is strongly modulated by large-scale modes of natural climate variability such as the El Niño–Southern Oscillation, whose positive phase is associated with increased compound event occurrence in the eastern equatorial Pacific and in the Indian Ocean by a factor of up to 4. Our results provide a first understanding of where, when, and why compound MHW and LChl events occur. Further studies are needed to identify the exact physical and biological drivers of these potentially harmful events in the ocean and their evolution under global warming.

Warming of the Indian Ocean weakens the Atlantic Niño - El Niño Southern Oscillation connection 

2021 ◽  
Author(s):  
Shreya Dhame ◽  
Andréa Taschetto ◽  
Agus Santoso ◽  
Giovanni Liguori ◽  
Katrin Meissner
Keyword(s):  
Indian Ocean ◽  
Atlantic Ocean ◽  
Southern Oscillation ◽  
Warming Trend ◽  
Equatorial Pacific ◽  
Ocean Warming ◽  
The West ◽  
Indian Ocean Warming ◽  
The Indian Ocean ◽  
Mean State

&lt;p&gt;The tropical Indian Ocean has warmed by 1 degree Celsius since the mid-twentieth century. This warming is likely to continue as the atmospheric carbon dioxide levels keep rising. Here, we discuss how the warming trend could influence the El Ni&amp;#241;o Southern Oscillation (ENSO) via interaction with the Pacific and the Atlantic Ocean mean state and variability. The warming trend leads to the strengthening of easterlies in the western equatorial Pacific, subsequent downwelling and increase of the mixed later depth in the west, and an increase in the subsurface temperature gradient across the equatorial Pacific. In the eastern equatorial Pacific, the response of upwelling ocean currents to surface wind stress decreases, resulting in a weakening of ENSO amplitude. The Indian Ocean warming influences ENSO via the Atlantic Ocean as well. There, it is associated with the strengthening of equatorial easterly winds, and anomalous warming in the west and upwelling induced cooling in the east, especially in austral winter, during the peak of the Atlantic Ni&amp;#241;o. Consequently, this results in a decrease of the amplitude of Atlantic Ni&amp;#241;o events and weakening of the Atlantic Ni&amp;#241;o-ENSO teleconnection, thereby hindering the transition of El Ni&amp;#241;o events to La Ni&amp;#241;a events. Thus, the Indian Ocean warming trend is found to modulate tropical Pacific and Atlantic mean state and variability, with implications for ENSO predictability under a warming climate.&lt;/p&gt;

Variability of the Intertropical Convergence Zone recorded in coral isotopic records from the central indian Ocean (Chagos Archipelago)

2004 ◽  
Vol 61 (3) ◽  
pp. 245-255 ◽  
Author(s):  
Miriam Pfeiffer ◽  
Wolf-Christian Dullo ◽  
Anton Eisenhauer
Keyword(s):  
Indian Ocean ◽  
Southern Oscillation ◽  
Major Change ◽  
Temporal Variations ◽  
Oxygen Isotopic Composition ◽  
Intertropical Convergence Zone ◽  
Boreal Winter ◽  
Convergence Zone ◽  
The Indian Ocean ◽  
Chagos Archipelago

We have analyzed the stable oxygen isotopic composition of two Porites corals from the Chagos Archipelago, which is situated in the geographical center of the Indian Ocean. Coral δ18O at this site reliably records temporal variations in precipitation associated with the Intertropical Convergence Zone (ITCZ). Precipitation maxima occur in boreal winter, when the ITCZ forms a narrow band across the Indian Ocean. The Chagos then lies within the center of the ITCZ, and rainfall is strongly depleted in δ18O. A 120-yr coral isotopic record indicates an alternation of wet and dry intervals lasting 15 to 20 yr. The most recent 2 decades are dominated by interannual variability, which is tightly coupled to the El Niño–Southern Oscillation (ENSO). This is unprecedented in the 120 yr of coral record. As the ITCZ is governed by atmospheric dynamics, this provides evidence of a major change in the coupled ENSO–monsoon system.

scholarly journals Moored Observations of Current and Temperature in the Alas Strait: Collected for Submarine Tailing Placement, Used for Calculating the Indonesian Throughflow

Oceanography ◽  
2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Dwi Susanto ◽  
◽  
Jorina Waworuntu ◽  
Windy Prayogo ◽  
Agus Setianto
Keyword(s):  
Indian Ocean ◽  
Southern Oscillation ◽  
Flow Direction ◽  
Open Pit ◽  
Boreal Summer ◽  
Boreal Winter ◽  
Indonesian Throughflow ◽  
Complete Evaluation ◽  
Easterly Wind ◽  
The Indian Ocean

Newly released current velocity and temperature measurements in the Alas Strait collected from November 2005 to February 2007 permit calculation of the mean and variable transport of the Indonesian Throughflow (ITF) in this region. These data were collected by the Environmental Division of the Amman Mineral Nusa Tenggara mining company to serve as a guide for the deep submarine placement of tailings produced by the Batu Hijau open pit copper-gold mine. Ocean currents, temperatures, and winds in the Alas Strait region exhibit intraseasonal and seasonal variability, with modulation at interannual timescales that may be associated with intraseasonal Kelvin waves, the regional southeast monsoon, the El Niño Southern Oscillation, and the Indian Ocean Dipole (IOD). Currents in the Alas Strait were found to flow steadily southward not only during the boreal summer from mid-April to October but also when a prolonged anomalously easterly wind associated with positive IOD extended this flow direction through the end of December 2006. A steady shear between the northward-flowing upper layer and the southward-flowing layer beneath was recorded from November 2005 to early April 2006 and from January to February 2007. The 2006 annual transport was –0.25 Sv toward the Indian Ocean and varied from 0.4 Sv in early April 2006 to –0.75 Sv in August 2006. Hence, Alas Strait transport plays a dual role in the total ITF, increasing it during boreal summer and reducing it during boreal winter. Northward flows tend to carry warmer water from the Indian Ocean to the Flores Sea, while the southward ITF flow carries cooler water to the Indian Ocean. Although the Alas Strait is located next to the Lombok Strait—one of the major ITF exit passages—they have different current and temperature characteristics. For a more complete evaluation of the ITF, the Alas Strait must be included in any future monitoring.

scholarly journals Compound high temperature and low chlorophyll extremes in the ocean over the satellite period

2020 ◽  
Author(s):  
Natacha Le Grix ◽  
Jakob Zscheischler ◽  
Charlotte Laufkötter ◽  
Cécile S. Rousseaux ◽  
Thomas L. Frölicher
Keyword(s):  
High Temperature ◽  
Indian Ocean ◽  
Extreme Events ◽  
Large Scale ◽  
Southern Oscillation ◽  
Chlorophyll Concentration ◽  
Equatorial Pacific ◽  
Compound Event ◽  
Eastern Equatorial Pacific ◽  
Compound Events

Abstract. Extreme events severely impact marine organisms and ecosystems. Of particular concern are compound events, i.e., when conditions are extreme for multiple potential ecosystem stressors such as temperature and chlorophyll. Yet, little is known about the occurrence, intensity and duration of such compound high temperature (aka marine heatwaves – MHWs) and low chlorophyll (LChl) extreme events, whether their distributions have changed in the past decades and what the potential drivers are. Here we use satellite-based sea surface temperature and chlorophyll concentration estimates to provide a first assessment of such compound extreme events. We reveal hotspots of compound MHW and LChl events in the equatorial Pacific, along the boundaries of the subtropical gyres, in the northern Indian Ocean, and around Antarctica. In these regions, compound events that typically last one week occur three to seven times more often than expected under the assumption of independence between MHWs and LChl events. The occurrence of compound MHW and LChl events varies on seasonal to interannual timescales. At the seasonal timescale, most compound events occur in summer in both hemispheres. At the interannual time-scale, the frequency of compound MHW and LChl events is strongly modulated by large-scale modes of natural climate variability such as the El Niño-Southern Oscillation, whose positive phase is associated with increased compound event occurrence in the eastern equatorial Pacific and in the Indian Ocean by a factor of up to four. Our results provide a first understanding of where, when and why compound MHW and LChl events occur. Further studies are needed to identify the exact physical and biological drivers of these potentially harmful events in the ocean and their evolution under global warming.

Sign in / Sign up

Export Citation Format

Share Document