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Bieito Fernandez Castro

@bfcastro.bsky.social
300 followers 338 following 21 posts

Physical oceanographer at @unisouthampton.bsky.social

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Reposted by Bieito Fernandez Castro
OSNAP @o-snap.org · 28/10/2025
👩‍🎓 PhD position at the National Oceanography Centre 👨‍🎓 🔍 Project: Heat, Freshwater and Oxygen Budgets in the Eastern Subpolar North Atlantic: Implications for UK continental shelf and European Weather. 🤝Team: Tiago, Neil, Lidia, & Bieito @bfcastro.bsky.social 🌊 Info: www.o-snap.org/phd-at-noc-uk/
o-snap.org
PhD at NOC (UK) - OSNAP
Dear all,  We are currently advertising an exciting PhD project opportunity on “Heat, Freshwater and Oxygen Budgets in the Eastern Subpolar North Atlantic: Implications for UK continental shelf and Eu...
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Bieito Fernandez Castro @bfcastro.bsky.social · 10/09/2025
What supplies nutrients to the surface layer of subtropical gyres is a long standing question in oceanography Recent work by Kate Oglethorpe shows that horizontal nutrient fluxes by mesoscale eddies are as (if not more) important than vertical fluxes: agupubs.onlinelibrary.wiley.com/doi/10.1029/...
agupubs.onlinelibrary.wiley.com
The Role of Mesoscale Eddy Stirring and Microscale Turbulence in Sustaining Biological Production in the Subtropical Gyres
Mesoscale eddy stirring and diapycnal mixing supply nutrients to the world ocean's subtropical gyres Mesoscale eddy stirring supply dominates over diapycnal mixing in the thermocline and plays a ...
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Bieito Fernandez Castro @bfcastro.bsky.social · 20/06/2025
Yep you're right! But net zero is compatible (and driven) with a significant release of young physosynthetic oxygen to the atmosphere. Which we are breathing! So I think both things make sense and we should be advocating for the importance that that has
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Bieito Fernandez Castro @bfcastro.bsky.social · 20/06/2025
The ocean is not a net source of oxygen to the atmosphere. But... primary producers at the surface need to release a non-negligible fraction of the oxygen they produce to air in order to compensate for the upwelling of oxygen depleted waters. I think makes our both viewpoints compatible:)
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Bieito Fernandez Castro @bfcastro.bsky.social · 20/06/2025
There is no need to burry organic matter in the sea floor to lock carbon away from the atmosphere. Organic matter remineralised within the water column is locked in as inorganic carbon, until circulation and mixing bring it back to the surface. The same goes for oxygen, the other way round
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Bieito Fernandez Castro @bfcastro.bsky.social · 20/06/2025
Most of respiration happens at the surface, but a non negligible fraction of respiration (10-20%?) occurs in the ocean interior. There, oxygen is depleted from water and can't get back in straight away. Therefore, there is a net release of oxygen to air. Maybe it is 10-20%×50%=5-10%. But not zero!
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Bieito Fernandez Castro @bfcastro.bsky.social · 20/06/2025
I disagree on the net zero claim. The bulk of the ocean is depleted in oxygen (oxygen concentration is below atmospheric equilibrium). This is because photosynthesis happens close to the surface, where oxygen leaves to the atmosphere.
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Reposted by Bieito Fernandez Castro
Prof Alessandro Tagliabue @altagliabue.bsky.social · 07/06/2025
Earth system models are plagued by uncertainties in the response of microbes to climate change. We leveraged metabolic insights from genome scale models when coupled to an ocean model in this new exciting work 🌊 www.science.org/doi/full/10....
science.org
Unveiling the link between phytoplankton molecular physiology and biogeochemical cycling via genome-scale modeling
A genome-enabled ESM built on genomic data assesses physiological acclimation and biogeochemical effects through nutrient stress.
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Reposted by Bieito Fernandez Castro
Eos @eos.org · 07/06/2025
Researchers modeled the paths of 100,000 particles of water backward in time over multiple decades to learn more about the origins of Subantarctic Mode Waters.
eos.org
On the Origins of Subantarctic Mode Waters - Eos
A modeling study shows how warm subtropical waters and cold Antarctic waters combine to form an Indo-Pacific water mass that plays a key role in Earth’s climate.
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Bieito Fernandez Castro @bfcastro.bsky.social · 02/06/2025
Thanks @aguadvances.bsky.social and @eos.org for sharing our work on the sources and formation process of sub-Antarctic Mode Waters!
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Bieito Fernandez Castro @bfcastro.bsky.social · 28/04/2025
@aguadvances.bsky.social
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Bieito Fernandez Castro @bfcastro.bsky.social · 19/04/2025
[7/7] Our results shed new light on the intricate nature of SAMWs, helping to predict and understand their role in slowing down future climate change.
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Bieito Fernandez Castro @bfcastro.bsky.social · 19/04/2025
[6/7] Subtropical source waters release heat into the atmosphere, whilst Antarctic waters absorb heat. Because of their different relative contribution to Indian and Pacific SAMWs, these SAMW pools play a different role in the climate system, as sources and sinks of atmospheric heat, respectively.
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Bieito Fernandez Castro @bfcastro.bsky.social · 19/04/2025
[5/7] Subtropical waters are the main precursor of Indian Ocean SAMWs (70%) but contribute a smaller amount (<40%) to Pacific SAMWs, which are mainly sourced from the upwelled CDW.
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Bieito Fernandez Castro @bfcastro.bsky.social · 19/04/2025
[4/7] We found that both subtropical and Antarctic sources contribute to SAMW formation and strong inter‐basin contrasts in their contributions, between the Indian and Pacific SAMW pools.
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Bieito Fernandez Castro @bfcastro.bsky.social · 19/04/2025
[3/7] We performed a flow-tracking experiment with a Southern Ocean model (B-SOSE) to address a long standing question about SAMWs: the extent to which they originate from southward‐flowing subtropical waters vs northward‐flowing Antarctic waters sourced by Circumpolar Deep Water (CDW) upwelling.
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Bieito Fernandez Castro @bfcastro.bsky.social · 19/04/2025
[2/7] Sub-Antarctic Mode Waters (SAMWs) form in the Southern Ocean, north of the Antarctic Circumpolar Current. These water masses are critical for the climate system, absorbing -and holding away from the atmosphere- vast amounts of anthropogenic heat and carbon dioxide.
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Bieito Fernandez Castro @bfcastro.bsky.social · 19/04/2025
[1/7] Check our latest paper investigating the sources, pathways and drivers leading to the formation of Sub-Antarctic Mode Waters! agupubs.onlinelibrary.wiley.com/doi/epdf/10....
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Reposted by Bieito Fernandez Castro
Fatima Pereira @fatimacpereira.bsky.social · 27/03/2025
📣 Exciting opportunity! We're hiring a #postdoctoral fellow in #gutmicrobiome research to explore the activity and function of the gut microbiome in situ and its regulation by the immune system.🦠🔬 Post based at @sotonbiosciences.bsky.social Apply here 👇 jobs.soton.ac.uk/Vacancy.aspx...
jobs.soton.ac.uk
Job Opportunity at the University of Southampton: Research Fellow (Postdoctoral) in Microbiology/Microbiome
Applications are invited for a Postdoctoral Research Fellow position in the Gut Microbiome Group, School of Biological Sciences at the University of Southampton. The University of Southampton is a wor...
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Bieito Fernandez Castro @bfcastro.bsky.social · 27/03/2025
About ten days left for this job! Don't miss the chance!
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Reposted by Bieito Fernandez Castro
Bjerknes Center for Climate Research (BCCR) @bjerknes.uib.no · 18/03/2025
The Greenland Sea is undergoing dramatic changes due to climate change, which has altered deep water production in the Northern Hemisphere. This is not just a regional issue—it has global consequences, especially for ocean circulation and carbon absorption.🧪🌊
bjerknes.uib.no
Dramatic Changes in the Greenland Sea
Due to climate change, deep water production has changed fundamentally in the Northern Hemisphere. This has major consequences for ocean circulation and…
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Bieito Fernandez Castro @bfcastro.bsky.social · 10/03/2025
WE ARE HIRING. Interested in ocean mixing? Come work with us in the ARIA-funded POLEMIX project to create and deploy a float-based mixing observing system in the subpolar North Atlantic. Applications here: jobs.soton.ac.uk/Vacancy.aspx... @sotonoceanearth.bsky.social @noc.ac.uk
jobs.soton.ac.uk
Job Opportunity at the University of Southampton: Research Fellow in Physical Oceanography
We are seeking to recruit a Research Fellow in Physical Oceanography to become a member of the School of Ocean and Earth Science at the University of Southampton. As part of the ‘POLEMIX: Autonomous P...
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Reposted by Bieito Fernandez Castro
JGR: Oceans @jgroceans.bsky.social · 08/01/2025
Fernández Castro et al. (2024) find that mesoscale eddies play a dominant role in mixing heat and salt in the North Atlantic, helping us to better understand the Atlantic Meridional Overturning Circulation and its future behavior. 🔗 doi.org/10.1029/2023... #AGUPubs
Graphical abstract for the study.
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Bieito Fernandez Castro @bfcastro.bsky.social · 18/02/2025
Great to have you onboard @gaelforget.net!
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Bieito Fernandez Castro @bfcastro.bsky.social · 17/02/2025
POLEMIX will deploy a mixing observing system in the North Atlantic and feed the observations into ocean models to disentangle the fate of freshwater and its impacts on dense water formation. Hiring soon! @sotonoceanearth.bsky.social @nocmarinephys.bsky.social @imev-mer.fr @mitpress.bsky.social
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Reposted by Bieito Fernandez Castro
Prof Michael Meredith 🌊🧪🥼❄️ @oceanandice.bsky.social · 15/02/2025
Sea ice in the Arctic and around Antarctica cool our climate, drive ocean circulation across the planet, and provide a unique habitat for polar ecosystems. Sea ice amounts have now fallen to their lowest since we started measuring them. This is not good. 🌊🥼❄️🧪 www.bbc.co.uk/news/article...
bbc.co.uk
World's sea-ice falls to record low
The world's frozen oceans keep the planet cool, but they currently have less ice than ever recorded before.
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Bieito Fernandez Castro @bfcastro.bsky.social · 14/02/2025
Great views of sea ice in the Greenland Sea
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Bieito Fernandez Castro @bfcastro.bsky.social · 06/02/2025
Soon on our way to the Fram strait thanks to a NERC-funded Seedcorn grant and our colleages at U Bergen. We will investigate organic matter transport and export along the East Greenland margin. @sotonoceanearth.bsky.social
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Reposted by Bieito Fernandez Castro
University of Southampton @unisouthampton.bsky.social · 04/12/2024
We are leading a new project which could transform our understanding of how the ocean ‘breathes’ - storing heat and greenhouse gases from the atmosphere 🌊 It will use sensors onboard high-tech floats to provide unprecedented detail on ocean mixing. Read more 👉 brnw.ch/UoS_News_Oce...
brnw.ch
Research set to transform our understanding of how the ocean breathes
Research set to transform our understanding of how the ocean breathes
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Reposted by Bieito Fernandez Castro
Seth Bushinsky @sethbushinsky.bsky.social · 27/11/2024
Two postdoc positions in my group are opening: First is part of SOCCOM3 (3 years, NSF funded, S. Ocean carbon/oxygen/nutrient budgets), Second is part of InMOS (4.25 yrs, Schmidt Sciences / OBVI funded, long-term oxygen/carbon flux and inventory constraints). More info: bushinskyoceanlab.org/people/
bushinskyoceanlab.org
People
Looking for two postdocs (SOCCOM and InMOS), details below. I am not currently planning to take on new students in Fall 2025. HI Cycles group at the 10th annual SOCCOM meeting at Princeton Universi…
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Reposted by Bieito Fernandez Castro
Robert Rohde @rarohde.bsky.social · 22/11/2024
A new paper led by Sebastian Sippel just appeared in Nature arguing that ocean temperature measurements in the early 20th century have a cold bias. It's a fun story illustrating the process of scientific discovery, so let me talk about it a bit. 🧵 www.nature.com/articles/s41...
nature.com
Early-twentieth-century cold bias in ocean surface temperature observations - Nature
Independent statistical reconstructions of the global mean surface temperature from either ocean or land data show that existing estimates of early-twentieth-century ocean surface temperatures are too...
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Reposted by Bieito Fernandez Castro
Emma Boland @emmaboland.bsky.social · 20/11/2024
Interested in how the ocean works?🌊 Want to find out more about how the wind, sun, sea ice and more impact nutrients in the Southern Ocean?🦠 Come do a PhD with me @bfcastro.bsky.social and others at @bas.ac.uk 🇦🇶 and @unisouthampton.bsky.social via the IGNITE DLA (ignite-dla.soton.ac.uk).
Advry for Funded PhD opportunity as part of the IGNITE Doctoral Landscape Award at the University of Southampton. Title: "What are the physical controls on nutrients in the Southern Ocean?" There is a 3D cutout diagram of the Southern Ocean with arrows indicating physical impacts on SAMW (Sub-Antarctic Mode Water) as well as the flow and mixing of nutrients. Text: "Nutrients from the Southern Ocean are fundamental to global ocean ecosystems and carbon uptake. The project will use a combination of data from different ocean models to figure out the physical drivers of the amount of nutrients in the Southern Ocean and the paths they take to get there. Supervisory Team from the British Antarctic Survey and the University of Southampton." There are thumbnail pictures of each of the Supervisory Team: Emma Boland, Biéto Fernandez Castro, Dave Munday, Yohei Takano. There are logos for the British Antarctic Survey and associated projects BIOPOLE and BIOCARBON.
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Reposted by Bieito Fernandez Castro
Emma Boland @emmaboland.bsky.social · 18/10/2024
Interested in how the ocean works?🌊 Want to find out more about how the wind, sun, sea ice and more impact nutrients in the Southern Ocean?🦠 Come do a PhD with me at the British Antarctic Survey 🇦🇶 and University of Southampton! www.findaphd.com/phds/project...
findaphd.com
What are the physical controls on nutrients in the Southern Ocean? at University of Southampton on FindAPhD.com
PhD Project - What are the physical controls on nutrients in the Southern Ocean? at University of Southampton, listed on FindAPhD.com
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