Fabrice Ardhuin

@fabriceardhuin.bsky.social

2.6K followers 170 following 340 posts

Earth scientist focusing on wind waves, currents and a few other things.

Videos

Geology 37%

Environmental science 31%

Posts Replies Media Videos

Fabrice Ardhuin @fabriceardhuin.bsky.social · 1d

Well, I just did 5 review over the past month ... and I refused to do at least as much. There are also too many journals publishing too many papers... at least in my field.

Reposted by Fabrice Ardhuin

Dominic Manchee @dpmanchee.bsky.social · 3d

Even small meteorite impacts can be destructive, say Kaali impact on Saaremaa Island, Estonia impact.uwo.ca/impact-crate.... Estimated impact 5-20 kilotons of TNT !

More info, Losiak et al (2016), DOI: 10.1111/maps.12616

Here is hillshade of Estonian Land Board 5m LIDAR showing clear crater rim.

Reposted by Fabrice Ardhuin

Frédéric Restagno @frestagn.bsky.social · 3d

En CPGE, à la fac, on distribue souvent des supports très structurés. Mais une question reste peu discutée :
👉 quels “blancs” laisse-t-on aux étudiants ?

Pas des trous au hasard, mais des espaces pour réfléchir, conjecturer, s’approprier. Les “blancs” sont une véritable décision pédagogique.

Facilitating note-taking with guided notes – students’ preferences regarding positions for blanks and preprinted parts

In traditional mathematics lectures given on the board, students are often busy taking notes and have trouble listening to the instructor simultaneously. One approach to address this problem is the...

www.tandfonline.com

Reposted by Fabrice Ardhuin

Patrick Marques @pmarques35.bsky.social · 3d

[1/8] Les travaux du BRGM et de l’université de Neuchâtel sur la source sous-marine de la Vise, au pied de l’étang de Thau, expliquent comment cet aquifère karstique stratégique s’inverse par intrusion saline lors de coups de vent et de sécheresse. #geography #geosciences

Comment préserver la réserve d’eau douce sous l’étang de Thau

A huit reprises depuis les années 1960, de l’eau salée s’est infiltrée dans la source sous-marine de la Vise, contaminant l’aquifère karstique exploité par plusieurs localités.

www.lemonde.fr

Reposted by Stefan Rahmstorf, Fabrice Ardhuin, Wim Thiery , and 2 more Stefan Rahmstorf, Fabrice Ardhuin, Wim Thiery, Juanjo Medina, Tim Stephens

Swinda Falkena @swinda.bsky.social · 4d

📢 New paper on the impacts of AMOC collapse on European hydroclimate. 🌊

We find an AMOC collapse would exacerbate drought conditions across Europe, linked to reduced precipitation. In combination with climate change droughts are expected to become more frequent and severe.

doi.org/10.5194/hess...

Changing European hydroclimate under a collapsed AMOC in the Community Earth System Model

Abstract. The Atlantic Meridional Overturning Circulation (AMOC) is expected to weaken or even collapse under anthropogenic climate change. Given the importance of the AMOC in the present-day climate,...

doi.org

Reposted by Fabrice Ardhuin

Australian Antarctic Program Partnership @antarctic.bsky.social · 4d

🌊🧵 1/ Vanderford Glacier, holding more than half-a-metre of global sea level rise, is retreating faster than any other in East #Antarctica (18.6 km of grounding line retreat 1996-2020!) It’s one of a number of glaciers in Vincennes Bay melted by deep warm water getting underneath.

📸 P. Harmsen/AAD

Reposted by Peter Thorne, Fabrice Ardhuin

NSF NCAR & UCAR @ncar-ucar.bsky.social · 6d

Hurricane Melissa produced the fastest hurricane winds to be recorded by a dropsonde, verified by reviewing data at NSF NCAR! Hurricane Melissa’s 252 mph wind gust surpassed the previous record from Typhoon Megi over the Western Pacific in 2010, where a dropsonde measured wind gusts of 248 mph.

Reposted by Fabrice Ardhuin

RFI @rfi.fr · 7d

Cap-Vert, Maurice et Seychelles «premiers pays d’Afrique subsaharienne» à avoir éliminé rougeole et rubéole

L’Organisation mondiale de la santé (OMS) a affirmé le 17 novembre 2025 que le Cap-Vert, Maurice et les Seychelles sont les « premiers pays d’Afrique subsaharienne à franchir cette étape historique » : éliminer la rougeole et la rubéole.

www.rfi.fr

Reposted by Fabrice Ardhuin

Martin Stevens @wildlifevision.bsky.social · 8d

The rare & beautiful violet sea snail - a predator of Portuguese Man O’War & by-the-wind sailors. It lives its whole life at the surface of the open ocean, using a bubble raft to stay afloat. It’s normally more common in warmer waters but occasionally seen here
#marinebiology #marinelife #oceanlife

Reposted by Fabrice Ardhuin

JGR: Oceans @jgroceans.bsky.social · 8d

The seabed rarely consists solely of bare sand: often other materials, such as shells are present. Kooistra et al., show shells have marked effects on bed roughness and sand transport 🐚 🌊

agupubs.onlinelibrary.wiley.com/doi/10.1029/...

Fabrice Ardhuin @fabriceardhuin.bsky.social · 8d

I'm very fortunate to work now on SWOT data (the most amazing source of wave measurements together with CFOSAT). I'm also working on the next challenge: measuring ocean currents from space with ODYSEA, because currents also impact waves!

odysea.ucsd.edu

That should be another launch around 2030

ODYSEA | Ocean DYnamics and Surface Exchange with the Atmosphere

odysea.ucsd.edu

Fabrice Ardhuin @fabriceardhuin.bsky.social · 8d

As Sentinel 6-B begins its mission, I'm thinking of all the scientists that have made the case for more accurate observation of the oceans, in particular Annie Cazenave, member of both FR and US academies of sciencies, and all the people around the world that have demonstrated the value of the data.

Group photo from the 2023 OSTST Meeting. https://sealevel.jpl.nasa.gov/events/58/ostst-2023/

Fabrice Ardhuin @fabriceardhuin.bsky.social · 8d

For the @esaearth.esa.int project we chose the WHALES retracker because:
1) open source (github.com/ne62rut/whales )
2) gives low noise globally and more data near the coast
3) successfully applied to all missions starting with ERS-1 (ERS-1 with WHALES will be in the CCI v5 dataset next year)

GitHub - ne62rut/whales

Contribute to ne62rut/whales development by creating an account on GitHub.

github.com

Fabrice Ardhuin @fabriceardhuin.bsky.social · 8d

The actual resolution also depends on the processing (retracking): giving more weights to near-nadir echoes, retrackers such as the Adaptive or WHALES retrackers acheive a higher effective resolution ... while at the same time reducing the "noise" in the wav height measurement.

Simulated map of "wave heights" that would be obtained by flying 100 altimeters side by side: the same data (simulated waveforms) is processed with three different cost functions for fitting the waveforms (taken from Passaro et al., 2025. https://arxiv.org/abs/2505.12881 )

Fabrice Ardhuin @fabriceardhuin.bsky.social · 8d

S6-B is also gives wave heights (and a few more parameters). It may not be the most accurate for waves but it is a key component of the observing system. S6B will first fly in tandem with S6A, allowing a detailed inter-calibration of all missions ostst.aviso.altimetry.fr/fileadmin/us...

Fabrice Ardhuin @fabriceardhuin.bsky.social · 8d

For the record, the correct list of sponsors for S6B is ESA, Eumetsat, NASA, the European Comission and CNES. But I'm not quite sure what this NASA graphics is supposed to say:

S1, S2, S3, S4, S5 and S6 are all doing very different things. True, S3s also carry altimeters (SRALs) .

Reposted by Fabrice Ardhuin

European Space Agency @esa.int · 8d

Mission confirmed ✅

#CopernicusEU Sentinel-6B is now in orbit and ready to begin its Launch & Early Operations phase with @operations.esa.int. The satellite is ready to continue a decades-long mission to track the height of the planet’s seas – a key measure of climate change.

Sentinel-6B launched to extend record of sea-level rise

The latest guardian of our oceans has taken its place in orbit. The Copernicus Sentinel-6B satellite is now circling Earth, ready to continue a decades-long mission to track the height of the planet’s...

esa.int

Fabrice Ardhuin @fabriceardhuin.bsky.social · 8d

S6-B is on the same orbit altiude as Jason-3 and Topex-Poseidon, around 1300 km which gives it a lower resolution for ocean wave measurement ... that is a function of the wave height: from 1.2 km radius of the footprint at Hs=2 m to 4.5 km at 20 m. Almost a factor 2 compared to CFOSAT

Fabrice Ardhuin @fabriceardhuin.bsky.social · 8d

Now that the satellite S6-B is going up to its 1300 km altitude orbit, you may take a few minutes to answer our survey about ocean wave measurements from space: forms.gle/HhQBhorViYNG...

that will help us prioritize activities for the Sea State CCI project ...

Ocean wave climate time series: what can we do for you? (a short 2-min survey)

The latest Sea State CCI dataset (version 4) is now available with level 2p (expert along-track data), level 3 (along-track all satellites combined), and level 4 (gridded) data, including nadir altime...

docs.google.com

Fabrice Ardhuin @fabriceardhuin.bsky.social · 8d

I happen to be the "science lead" for the European Space Agency "Sea State" climate change initiative, coordinating the exploration of ocean wave climate time series from both imaging radars and radar altimeters. climate.esa.int/en/projects/...

We are providing advanced processing and monitoring

Sea State

The Sea State project is developing an 18-year data set (2002- 2020) capitalising on the rich satellite altimeter, SAR imager, and other data holdings available during that period.

climate.esa.int

Fabrice Ardhuin @fabriceardhuin.bsky.social · 8d

Satellite launches may all look routine... but well, bad things can happen, from a rocket failure (think Cryosat) to near-collision of S1-A requiring manoeuvers few hours after launch. Getting these new observations will continue time series of sea level but also of ocean wave heights

not quite up to date chart of of satellite missions from 1985 to 2030, including nadir and near-nadir altimeters (solid bars), and missions monitoring ocean wave spectra (open boxes) using C-band Synthetic Aperture Radars (red), and real aperture radars in Ku-band (black) or Ka-band (blue). The lighter color (grey and
blue) bars correspond to altimeters using Delay-Doppler processing. Source: CEOS database http: //database.eohandbook.com/). (B) example of 1-day coverage for Hs measurements with 4 satellite altimeters (C) snapshot of a ’fireworks’ plot, the showing the height (size of symbols) peak periods (colors), and directions (barbs) of swell partitions derived from Sentinel-1A and Sentinel-1B wave mode data. Such plots are produced routinely by CMEMS.

Fabrice Ardhuin @fabriceardhuin.bsky.social · 8d

S6B is a collaboration between Europe (ESA, Eumetsat) and the USA (NASA), following up the USA-France collaborative missions Topex-Poseidon, Jason ... Indeed, the main instrument on S6B, the radar altimeter, is a Poseidon-4 instrument, made by Thales Alenia Space in France.

Fabrice Ardhuin @fabriceardhuin.bsky.social · 8d

A few days ago we had the launch of satellite S1-D (the 4th in the series of imaging radars of the Copernicus program)... today is the turn of Sentinel 6-B: the second of the reference radar altimeter (not imager) missions. Lift off in 5 min

www.youtube.com/live/6tyr0ld...
or watch.esa.int/two/

Sentinel-6B Launch

YouTube video by NASA

www.youtube.com

Reposted by Fabrice Ardhuin

joeymaier 🌊 @joeymaier.bsky.social · 9d

'Dr Michelle Taylor, a University of Essex scientist who led the voyage, said: "If anything brushes up against them, they're doomed, unfortunately. Then to be absorbed slowly over time is a grim way of going."

Carnivorous 'death-ball' sponge share.google/pcKssFW9bX1E...

Carnivorous 'death-ball' sponge is team's oddest deep-sea find

The unusual creature lurks more than two miles (3.2km) deep in a trench in the Southern Ocean.

share.google

Reposted by Fabrice Ardhuin

Harald Sodemann @haraldsodemann.bsky.social · 11d

Currently a large outbreak of cold, Arctic air is making its way south over the Norwegian Sea. The amazing mesh structure (called open-cell convection) in the satellite image (coloured image) is really hard for weather forecast models (grey image) to get 'right' @bjerknes.uib.no #ISOSCAN_project

Reposted by Fabrice Ardhuin

Carbon Brief @carbonbrief.org · 12d

NEW – Met Office: Ten years of naming UK storms to warn the public | Holly Clements @metoffice.gov.uk

Read here ⬇️

Met Office: Ten years of naming UK storms to warn the public - Carbon Brief

Storm naming is a public safety tool that makes severe weather easier to remember, talk about and follow.

www.carbonbrief.org

Reposted by Fabrice Ardhuin, Gavin A. Schmidt

Paul Halpern @phalpern.bsky.social · 13d

Tributes at Bryn Mawr College to the brilliant mathematician Emmy Noether, who spent her final years there. Noether revolutionized the methods of modern physics by identifying continuous symmetry groups with conservation laws. The third image is her grave marker.

#Science #Mathematics #Physics

Reposted by Fabrice Ardhuin

Badvertising @badvertising.bsky.social · 13d

🌍 What do global cities such as Amsterdam, Stockholm and Edinburgh all have in common?

These major cities have ALL banned fossil fuel adverts. These ads have massive climate and health impacts, all while targeting politically influential decision makers.

Reposted by Scott C. Doney, Fabrice Ardhuin

JGR: Oceans @jgroceans.bsky.social · 14d

Ask not what your journal can do for you—ask what you can do for your journal 🌊

JGR:Oceans is now looking for new Editors and Associate Editors, if you're interested get in touch. We don't bite! 😀

Editor and Associate Editor positions at JGR:Oceans

Fabrice Ardhuin @fabriceardhuin.bsky.social · 19d

Petite clarification, contrairement à ce que titre Science et Avenir, nous n'avons pas du tout travaillé sur les vagues scélérates ... mais sur les plus hautes vagues en mer, qui ne sont pas scélérates: www.sciencesetavenir.fr/tag_theme/va...

... ma version est là: www.umr-lops.fr/Le-LOPS/Actu...

Vague scélérate : actu, infos et vidéos

Retrouvez toutes les infos sur Vague scélérate : articles, vidéos et photos consacrés au thème Vague scélérate par la rédaction de Sciences et Avenir.

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