Seafloor seismicity, Antarctic ice-sounds, cetacean vocalizations and long-term ambient sound in the Indian Ocean basin

In this study, we investigated extreme droughts in the Indochina peninsula and their relationship with the Indian Ocean Dipole (IOD) mode. Areas most vulnerable to drought were analyzed via statistical simulations of the IOD based on historical observations. Results of the long-term trend analysis indicate that areas with increasing spring (March–May) rainfall are mainly distributed along the eastern coast (Vietnam) and the northwestern portions of the Indochina Peninsula (ICP), while Central and Northern Laos and Northern Cambodia have witnessed a reduction in spring rainfall over the past few decades. This trend is similar to that of extreme drought. During positive IOD years, the frequency of extreme droughts was reduced throughout Vietnam and in the southwestern parts of China, while increased drought was observed in Cambodia, Central Laos, and along the coastline adjacent to the Myanmar Sea. Results for negative IOD years were similar to changes observed for positive IOD years; however, the eastern and northern parts of the ICP experienced reduced droughts. In addition, the results of the statistical simulations proposed in this study successfully simulate drought-sensitive areas and evolution patterns of various IOD changes. The results of this study can help improve diagnostic techniques for extreme droughts in the ICP.

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ENSO and climatic signals across the Indian Ocean Basin in the global context: part I, interannual composite patterns

International Journal of Climatology ◽

10.1002/1097-0088(200009)20:11<1285::aid-joc536>3.0.co;2-r ◽

2000 ◽

Vol 20 (11) ◽

pp. 1285-1327 ◽

Cited By ~ 196

Author(s):

C.J.C. Reason ◽

R.J. Allan ◽

J.A. Lindesay ◽

T.J. Ansell

Keyword(s):

Indian Ocean ◽

Ocean Basin ◽

Global Context ◽

The Indian Ocean ◽

Climatic Signals

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INCREASE OF THE THERMOCLINE LAYER DUE TO TSUNAMI 2004 IN NANGRO ACEH DARUSSALAM WATERS

Jurnal Ilmu dan Teknologi Kelautan Tropis ◽

10.29244/jitkt.v3i1.7840 ◽

2011 ◽

Vol 3 (1) ◽

Author(s):

Hadikusumah Hadikusumah ◽

J. D. Lekalete

Keyword(s):

Indian Ocean ◽

Light Transmission ◽

Mixed Layer Depth ◽

Heat Content ◽

Annual Variations ◽

The Indian Ocean ◽

Local Water ◽

Straits Of Malacca ◽

Tsunami Energy

Research of physical oceanographic conditions post-tsunami was carried out and subsequently compared with the pre-tsunami 1998. Measurement of suhu, salinity and light transmission was conducted by CTDSBE911pls Model. Results showed that the flow in the Straits of Malacca flowed into the northwest and turned back into the Strait of Bengal and the next rotation into the flow of waters along the west coast of Nangro Aceh Darusalam (NAD). The mainstream off coast NAD in the Indian Ocean flowed to the northwest. Upper thermocline layer (17 m to 50 m) moved upward in 2005 and 2006 compared with previous data 1998 (90 m to 125 m). The moving upward thermocline in 2006 was allegedly due to the influence of Indian Ocean Dipole (IOD) positive. This requires further verification through long-term data collection to determine the monthly and annual variations, which will be compared with previous research. Light transmission (Tx) in 2005 from the surface to near the bottom (water column) was found lower than the year 1998 and 2006. This result was allegedly caused by resuspension from the seabed by energy turbulent produced by the tsunami. Heat content between 5 to 65 m depth in 2005 was higher than in 1998 and 2006. The higher heat content during the year of 2005 (post tsunami) was caused by friction due to the influence of tsunami energy, which predominantly found in the mixed layer depth. Type of water masses in the study area was a mixing between the local water mass, Malacca Strait Water (MSA), Bay of Bengal Water (BBW) under the influence of Arab Waters (AW), and the Indian Deep Water (IDW).Keywords: current, thermocline, heat content, watermass type, and Nangro Aceh Darusalam

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Understanding the Weakening Relationship of the Pacific Decadal Oscillation and Indian Ocean Basin Mode During Boreal Winter

10.21203/rs.3.rs-640927/v1 ◽

2021 ◽

Author(s):

Jin-Sil Hong ◽

Sang-Wook Yeh ◽

Young-Min Yang ◽

Young-Kwon Lim ◽

Kyu-Myong Kim

Keyword(s):

Indian Ocean ◽

Pacific Decadal Oscillation ◽

Climate Model ◽

Ocean Basin ◽

Boreal Winter ◽

Indian Ocean Basin Mode ◽

The Pacific ◽

Basin Mode ◽

Relationship Of

Abstract While it is known that the Pacific Decadal Oscillation (PDO) leads the Indian Ocean Basin Mode (IOBM) with the same phase via the atmospheric bridge, we found that the relationship of PDO-IOBM during boreal winter is not stationary. Here, we investigated the PDO-IOBM relationship changes on low-frequency timescales by analyzing the observations, a long-term simulation of climate model with its large ensembles as well as the pacemaker experiments. A long-term simulation of climate model with its large ensemble simulations indicated that the non-stationary relationship of PDO-IOBM is intrinsic in a climate system and it could be at least partly due to internal climate variability. In details, we compared the PDO structures during the entire period with those during the period when the PDO-IOBM relationship was weak (i.e., 1976-2006). We found that the structures of sea surface temperature (SST) as well as its associated tropical Pacific convective forcing during the negative phase of PDO for 1976-2006 are far away from the typical structures of the negative PDO phase during the entire period, which were responsible for the weakening relationship of the PDO-IOBM in the observation. The results of the two pacemaker experiments support that a non-stationary relationship of PDO-IOBM is primarily due to the SST forcing in the Pacific.

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Measuring the Marine Soundscape of the Indian Ocean with Southern Elephant Seals Used as Acoustic Gliders of Opportunity

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-16-0124.1 ◽

2017 ◽

Vol 34 (1) ◽

pp. 207-223 ◽

Cited By ~ 6

Author(s):

Dorian Cazau ◽

Julien Bonnel ◽

Joffrey Jouma’a ◽

Yves le Bras ◽

Christophe Guinet

Keyword(s):

Indian Ocean ◽

Low Frequency ◽

Sound Field ◽

Elephant Seals ◽

Ambient Sound ◽

Southern Elephant Seals ◽

Operational Systems ◽

The Indian Ocean ◽

Passive Acoustic ◽

Free Ranging

AbstractThe underwater ambient sound field contains quantifiable information about the physical and biological marine environment. The development of operational systems for monitoring in an autonomous way the underwater acoustic signal is necessary for many applications, such as meteorology and biodiversity protection. This paper develops a proof-of-concept study on performing marine soundscape analysis from acoustic passive recordings of free-ranging biologged southern elephant seals (SES). A multivariate multiple linear regression (MMLR) framework is used to predict the measured ambient noise, modeled as a multivariate acoustic response, from SES (depth, speed, and acceleration) and environmental (wind) variables. Results show that the acoustic contributions of SES variables affect mainly low-frequency sound pressure levels (SPLs), while frequency bands above 3 kHz are less corrupted by SES displacement and allow a good measure of the Indian Ocean soundscape. Also, preliminary results toward the development of a mobile embedded weather sensor are presented. In particular, wind speed estimation can be performed from the passive acoustic recordings with an accuracy of 2 m s−1, using a rather simple multiple linear model.

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Impact of Indo-Pacific Feedback Interactions on ENSO Dynamics Diagnosed Using Ensemble Climate Simulations

Journal of Climate ◽

10.1175/jcli-d-11-00287.1 ◽

2012 ◽

Vol 25 (21) ◽

pp. 7743-7763 ◽

Cited By ~ 49

Author(s):

A. Santoso ◽

M. H. England ◽

W. Cai

Keyword(s):

Indian Ocean ◽

Climate Model ◽

Southern Oscillation ◽

Ocean Basin ◽

Climate Feedback ◽

Enso Events ◽

Thermocline Feedback ◽

Enso Dynamics ◽

The Indian Ocean ◽

The Impact

The impact of Indo-Pacific climate feedback on the dynamics of El Niño–Southern Oscillation (ENSO) is investigated using an ensemble set of Indian Ocean decoupling experiments (DCPL), utilizing a millennial integration of a coupled climate model. It is found that eliminating air–sea interactions over the Indian Ocean results in various degrees of ENSO amplification across DCPL simulations, with a shift in the underlying dynamics toward a more prominent thermocline mode. The DCPL experiments reveal that the net effect of the Indian Ocean in the control runs (CTRL) is a damping of ENSO. The extent of this damping appears to be negatively correlated to the coherence between ENSO and the Indian Ocean dipole (IOD). This type of relationship can arise from the long-lasting ENSO events that the model simulates, such that developing ENSO often coincides with Indian Ocean basin-wide mode (IOBM) anomalies during non-IOD years. As demonstrated via AGCM experiments, the IOBM enhances western Pacific wind anomalies that counteract the ENSO-enhancing winds farther east. In the recharge oscillator framework, this weakens the equatorial Pacific air–sea coupling that governs the ENSO thermocline feedback. Relative to the IOBM, the IOD is more conducive for ENSO growth. The net damping by the Indian Ocean in CTRL is thus dominated by the IOBM effect which is weaker with stronger ENSO–IOD coherence. The stronger ENSO thermocline mode in DCPL is consistent with the absence of any IOBM anomalies. This study supports the notion that the Indian Ocean should be viewed as an integral part of ENSO dynamics.

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From Zanzibar to Zaytun: Iranian Merchants across the Indian Ocean Basin

Iran and the Caucasus ◽

10.1163/1573384x-20180203 ◽

2018 ◽

Vol 22 (2) ◽

pp. 139-154

Author(s):

Richard Foltz

Keyword(s):

Popular Culture ◽

Indian Ocean ◽

Ocean Basin ◽

16Th Century ◽

Maritime Trade ◽

Archaeological Data ◽

Indian Ocean Trade ◽

The Indian Ocean

The role of Iranian merchants in the maritime trade of the Indian Ocean basin from antiquity up to the 16th century is often underestimated. From scholarly histories to popular culture the “Muslim sailor” is typically portrayed as being an Arab. In fact, from pre-Islamic times the principal actors in Indian Ocean trade were predominantly Persian, as attested by the archaeological data, local written records, and the names of places and individuals.

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