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Dynamical Response of the Arabian Sea Oxygen Minimum Zone to the Extreme Indian Ocean Dipole Events in 2016 and 2019

Abstract.

"The Indian Ocean Dipole (IOD) plays a crucial role in shaping local and global environments, yet its effects on interannual variability of the Arabian Sea oxygen minimum zone (ASOMZ) remains poorly understood. Here, we used a coupled physical-biogeochemical model to investigate the dynamical response of the ASOMZ to extreme negative (2016) and positive (2019) IOD events. Our findings revealed that the suboxic area of the ASOMZ reduced (expanded) by ∼27% (∼28%) after the negative (positive) IOD event. [...]".

 

Source: Wiley Online Library
Authors: Zhiwei Zhang et al.
DOI: https://doi.org/10.1029/2023GL104226

Read the full article here.


Reconstruction of dissolved oxygen in the Indian Ocean from 1980 to 2019 based on machine learning techniques

Abstract.

"Oceanic dissolved oxygen (DO) decline in the Indian Ocean has profound implications for Earth’s climate and human habitation in Eurasia and Africa. Owing to sparse observations, there is little research on DO variations, regional comparisons, and its relationship with marine environmental changes in the entire Indian Ocean. In this study, we applied different machine learning algorithms to fit regression models between measured DO, ocean reanalysis physical variables, and spatiotemporal variables. [...]".

 

Source: Frontiers in Marine Science
Authors: Sheng Huang et al.
DOI: https://doi.org/10.3389/fmars.2023.1291232

Read the full article here.


Preprint: Unique ocean circulation pathways reshape the Indian Ocean oxygen minimum zone with warming

Abstract.

"The global ocean is losing oxygen with warming. Observations and Earth system model projections suggest, however, that this global ocean deoxygenation does not equate to a simple and systematic expansion of tropical oxygen minimum zones (OMZs). Previous studies have focused on the Pacific Ocean; they showed that the outer OMZ deoxygenates and expands as oxygen supply by advective transport weakens, the OMZ core oxygenates and contracts due to a shift in the composition of the source waters supplied by slow mixing, and in between these two regimes, oxygen is redistributed with little effect on OMZ volume. [...]".

 

Source: EGUsphere 
Authors: Sam Ditkovsky et al.
DOI: https://doi.org/10.5194/egusphere-2023-1082

Read the full article here.


Indian Ocean glacial deoxygenation and respired carbon accumulation during mid-late Quaternary ice ages

Abstract.

"Reconstructions of ocean oxygenation are critical for understanding the role of respired carbon storage in regulating atmospheric CO2. Independent sediment redox proxies are essential to assess such reconstructions. Here, we present a long magnetofossil record from the eastern Indian Ocean in which we observe coeval magnetic hardening and enrichment of larger, more elongated, and less oxidized magnetofossils during glacials compared to interglacials over the last ~900 ka. Our multi-proxy records of redox-sensitive magnetofossils, trace element concentrations, and benthic foraminiferal Δδ13C consistently suggest a recurrence of lower O2 [...]".

 

Source: Nature
Authors: Liao Chang et al.
DOI: https://doi.org/10.1038/s41467-023-40452-1

Read the full article here.


Cretaceous southern high latitude benthic foraminiferal assemblages during OAE 2 at IODP Site U1516, Mentelle Basin, Indian Ocean

Abstract.

"At Site U1516 (Mentelle Basin, southeast Indian Ocean, offshore western Australia), the International Ocean Discovery Program (IODP) Expedition 369 recovered an almost complete pelagic record of the Upper Cretaceous, including the Oceanic Anoxic Event 2 (OAE 2). To better understand paleoenvironmental changes across OAE 2, 32 samples were analysed for benthic foraminiferal abundance data that represent one of the few benthic foraminiferal datasets spanning the OAE 2 in the southern high latitudes. [...]".

 

Source: Science Direct
Authors: Erik Wolfgring et al.
DOI: https://doi.org/10.1016/j.cretres.2023.105555

Read the full article here.


Ostracod response to monsoon and OMZ variability over the past 1.2 Myr

Abstract. 

"We present the first continuous middle through late Pleistocene record of fossil ostracods from the Maldives in the northern Indian Ocean, derived from sediment cores taken at Site U1467 by Expedition 359 of the International Ocean Discovery Program (IODP). Site U1467 lies at 487 m water depth in the Inner Sea of the Maldives archipelago, an ideal place for studying the effects of the South Asian Monsoon (SAM) system on primary productivity, intermediate depth ocean circulation, and the regional oxygen minimum zone (OMZ). [...]". 

 

Source: Science Direct 
Authors: Carlos A. Alvarez Zarikian et al.
DOI: https://doi.org/10.1016/j.marmicro.2022.102105

Read the full article here.


Coastlines at Risk of Hypoxia From Natural Variability in the Northern Indian Ocean

Abstract. 

"Coastal hypoxia—harmfully low levels of oxygen—is a mounting problem that jeopardizes coastal ecosystems and economies. The northern Indian Ocean is particularly susceptible due to human-induced impacts, vast naturally occurring oxygen minimum zones, and strong variability associated with the seasonal monsoons and interannual Indian Ocean Dipole (IOD). We assess how natural factors influence the risk of coastal hypoxia by combining a large set of oxygen measurements with satellite observations to examine how the IOD amplifies or suppresses seasonal hypoxia tied to the Asian Monsoon. We show that on both seasonal and interannual timescales hypoxia is controlled by wind- and coastal Kelvin wave-driven upwelling of oxygen-poor waters onto the continental shelf and reinforcing biological feedbacks (increased subsurface oxygen demand). [...]".

 

Source: Global Biogeochemical Cycles
Authors: Jenna Pearson et al.
DOI: https://doi.org/10.1029/2021GB007192

Read the full article here.


Impacts of Ocean Currents on the South Indian Ocean Extratropical Storm Track through the Relative Wind Effect

Abstract.

"This study examines the role of the relative wind (RW) effect (wind relative to ocean current) in the regional ocean circulation and extratropical storm track in the south Indian Ocean. Comparison of two high-resolution regional coupled model simulations with and without the RW effect reveals that the most conspicuous ocean circulation response is the significant weakening of the overly energetic anticyclonic standing eddy off Port Elizabeth, South Africa, a biased feature ascribed to upstream retroflection of the Agulhas Current (AC).[...]"

 

Source: AMS- American Meteorological Sciety 
Authors: Hyodae Seo et al.
DOI: https://doi.org/10.1175/JCLI-D-21-0142.1

Read the full article here.


Observed Seasonal and Interannual Controls on Coastal Oxygen and Dead Zones in the Indian Ocean

Abstract.

"A major concern is that global de-oxygenation will expand Oxygen minimum zones (OMZs) and favor coastal dead zones (DZs) where already low oxygen levels threaten ecosystems and adjacent coastal economies. The northern Indian ocean is home to both intense OMZs and DZs, and is surrounded by many kilometers of biodiverse and commercially valuable coastline. Exchanges between OMZs and shelf waters that contribute to coastal DZs are subject to the strong monsoonal seasonal cycle[...]"

 

Source: EGU General Assambly
Authors: Jenna Pearson et al.
DOI: https://doi.org/10.5194/egusphere-egu21-1421

Read the full article here.


A global viral oceanography database (gVOD)

Abstract.

"Virioplankton are a key component of the marine biosphere in maintaining diversity of microorganisms and stabilizing ecosystems. They also contribute greatly to nutrient cycles/cycling by releasing organic matter after lysis of hosts. In this study, we constructed the first global viral oceanography database (gVOD) by collecting 10 931 viral abundance (VA) data and 727 viral production (VP) data, along with host and relevant oceanographic parameters when available. Most VA data were obtained in the North Atlantic (32 %) and North Pacific (29 %) oceans, while the southeast Pacific[...]"

 

Source: Earth System Science Data 
Authors: Le Xie et al.
DOI: https://doi.org/10.5194/essd-13-1251-2021

Read the full article here.


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