Wednesday, May 21, 2025

NASA, French SWOT satellite offers big view of small ocean features

 
Sunlight reflects off the ocean surface near Norfolk, Virginia, in this 1991 space shuttle image, highlighting swirling patterns created by features such as internal waves, which are produced when the tide moves over underwater features.
Data from the international SWOT mission is revealing the role of smaller-scale waves and eddies. 
Small things matter, at least when it comes to ocean features like waves and eddies.
A recent NASA-led analysis using data from the SWOT (Surface Water and Ocean Topography) satellite found that ocean features as small as a mile across potentially have a larger impact on the movement of nutrients and heat in marine ecosystems than previously thought.
Too small to see well with previous satellites, but too large to see in their entirety with ship-based instruments, these relatively small ocean features fall into a category known as the submesoscale.
The SWOT satellite, a joint effort between NASA and the French space agency CNES (Centre National d’Études Spatiales), can observe these features and is demonstrating just how important they are, driving much of the vertical transport of things like nutrients, carbon, energy, and heat within the ocean.
They also influence the exchange of gases and energy between the ocean and atmosphere.
 

From NASA


The international mission collects two-dimensional views of smaller waves and currents that are bringing into focus the ocean’s role in supporting life on Earth.

Small things matter, at least when it comes to ocean features like waves and eddies.
A recent NASA-led analysis using data from the SWOT (Surface Water and Ocean Topography) satellite found that ocean features as small as a mile across potentially have a larger impact on the movement of nutrients and heat in marine ecosystems than previously thought.

Too small to see well with previous satellites but too large to see in their entirety with ship-based instruments, these relatively small ocean features fall into a category known as the submesoscale.
The SWOT satellite, a joint effort between NASA and the French space agency CNES (Centre National d’Études Spatiales), can observe these features and is demonstrating just how important they are, driving much of the vertical transport of things like nutrients, carbon, energy, and heat within the ocean.
They also influence the exchange of gases and energy between the ocean and atmosphere.

“The role that submesoscale features play in ocean dynamics is what makes them important,” said Matthew Archer, an oceanographer at NASA’s Jet Propulsion Laboratory in Southern California.
Some of these features are called out in the animation below, which was created using SWOT sea surface height data. 
 
This animation shows small ocean features — including internal waves and eddies — derived from SWOT observations in the Indian, Atlantic, and Pacific oceans, as well as the Mediterranean Sea.
White and lighter blue represent higher ocean surface heights compared to darker blue areas.
The purple colors shown in one location represent ocean current speeds.

NASA’s Scientific Visualization Studio

“Vertical currents move heat between the atmosphere and ocean, and in submesoscale eddies, can actually bring up heat from the deep ocean to the surface, warming the atmosphere,” added Archer, who is a coauthor on the submesoscale analysis published in April in the journal Nature.
Vertical circulation can also bring up nutrients from the deep sea, supplying marine food webs in surface waters like a steady stream of food trucks supplying festivalgoers.

“Not only can we see the surface of the ocean at 10 times the resolution of before, we can also infer how water and materials are moving at depth,” said Nadya Vinogradova Shiffer, SWOT program scientist at NASA Headquarters in Washington.

Fundamental Force

Researchers have known about these smaller eddies, or circular currents, and waves for decades.
From space, Apollo astronauts first spotted sunlight glinting off small-scale eddies about 50 years ago.
And through the years, satellites have captured images of submesoscale ocean features, providing limited information such as their presence and size.
Ship-based sensors or instruments dropped into the ocean have yielded a more detailed view of submesoscale features, but only for relatively small areas of the ocean and for short periods of time.

The SWOT satellite measures the height of water on nearly all of Earth’s surface, including the ocean and freshwater bodies, at least once every 21 days.
The satellite gives researchers a multidimensional view of water levels, which they can use to calculate, for instance, the slope of a wave or eddy.
This in turn yields information on the amount of pressure, or force, being applied to the water in the feature.
From there, researchers can figure out how fast a current is moving, what’s driving it and —combined with other types of information — how much energy, heat, or nutrients those currents are transporting.

“Force is the fundamental quantity driving fluid motion,” said study coauthor Jinbo Wang, an oceanographer at Texas A&M University in College Station.
Once that quantity is known, a researcher can better understand how the ocean interacts with the atmosphere, as well as how changes in one affect the other.

Prime Numbers

Not only was SWOT able to spot a submesoscale eddy in an offshoot of the Kuroshio Current — a major current in the western Pacific Ocean that flows past the southeast coast of Japan — but researchers were also able to estimate the speed of the vertical circulation within that eddy.
When SWOT observed the feature, the vertical circulation was likely 20 to 45 feet (6 to 14 meters) per day.

This is a comparatively small amount for vertical transport.
However, the ability to make those calculations for eddies around the world, made possible by SWOT, will improve researchers’ understanding of how much energy, heat, and nutrients move between surface waters and the deep sea.

Researchers can do similar calculations for such submesoscale features as an internal solitary wave — a wave driven by forces like the tide sloshing over an underwater plateau.
The SWOT satellite spotted an internal wave in the Andaman Sea, located in the northeastern part of the Indian Ocean off Myanmar.
Archer and colleagues calculated that the energy contained in that solitary wave was at least twice the amount of energy in a typical internal tide in that region.

This kind of information from SWOT helps researchers refine their models of ocean circulation.
A lot of ocean models were trained to show large features, like eddies hundreds of miles across, said Lee Fu, SWOT project scientist at JPL and a study coauthor.
“Now they have to learn to model these smaller scale features.
That’s what SWOT data is helping with.”

Researchers have already started to incorporate SWOT ocean data into some models, including NASA’s ECCO (Estimating the Circulation and Climate of the Ocean).
It may take some time until SWOT data is fully a part of models like ECCO.
But once it is, the information will help researchers better understand how the ocean ecosystem will react to a changing world.

More About SWOT

The SWOT satellite was jointly developed by NASA and CNES, with contributions from the Canadian Space Agency (CSA) and the UK Space Agency.
Managed for NASA by Caltech in Pasadena, California, JPL leads the U.S.
component of the project.
For the flight system payload, NASA provided the Ka-band radar interferometer (KaRIn) instrument, a GPS science receiver, a laser retroreflector, a two-beam microwave radiometer, and NASA instrument operations.
The Doppler Orbitography and Radioposition Integrated by Satellite system, the dual frequency Poseidon altimeter (developed by Thales Alenia Space), the KaRIn radio-frequency subsystem (together with Thales Alenia Space and with support from the UK Space Agency), the satellite platform, and ground operations were provided by CNES.
The KaRIn high-power transmitter assembly was provided by CSA.

Links :

Tuesday, May 20, 2025

President Trump and the name Persian Gulf


Persian Gulf (Britannica)
 
From Tehran Times by Kourosh Ahmadi

TEHRAN - As we noted during his stay in the region, President Trump forwent wisely tinkering with geographical names and discarded the ostensible preliminary idea of using a different name for the Persian Gulf.
A report by the AP pointing to this eventuality has stirred emotional reactions among the Iranians from all different walks of life.

Had President Trump gone ahead with the reported plan, he would have deviated from the traditional and formal US policy on Gulf nomenclature that had honored the name Persian Gulf since the creation of the United States.
That would also have gone counter to the norms and principles that govern the standardization of geographical names and the consensus resolutions of the United Nations Conference on the Standardization of Geographical Names.

Hereafter, I explain how deeply the name Persian Gulf is rooted in the tradition of the American name standardization and foreign policy traditions:

The term ‘Persian Gulf’ adopted by the US specialized agencies

The US became the first government to establish an office entrusted with standardising geographical and administrative names.
Created in 1890, the United States Board of Geographic Names (USBGN) was the first national body set up “to deal with contradictions and inconsistencies among many names, applications and spellings…” 
Decisions of the Board are accepted as binding by all departments and agencies of the Federal Government.
Official US bodies, including diplomatic, intelligence and military agencies, rely on the USBGN for accurate names (p. 58).


Kourosh Ahmadi is a former diplomat and author of the book titled "Naming the Persian Gulf: The Roots of a Political Controversy", Ithaca Publishers, London, 2017

Based on the recommendation of this body, the policy has always been to ‘cooperate wherever possible’ with foreign governments to use a local name, with the ‘optional use’ of conventional English names (p.
61).
As all US departments are generally required to use formally correct place names in their communications with foreign governments, they also rely on names decided jointly by the USBGN and the State Department (p.125).
 
19th Century reconstruction of 194 BC Eratosthenes' map, Denoting Persian Gulf

‘Persikos Kolpos’ [Persian Gulf], which is the oldest toponym for a body of water, was first used around 500 BC by Hecataeus (p. 39), the Greek geographer and historian, and remained the only universally used term up to the political challenge coming from Pan-Arabism in the 1960s.
This designation was sanctioned for US government use since a decision made by the USBGN and the Department of State (DOS)’s Board of Geographical Names in 1917.

The National Geospatial-Intelligence Agency (NGA) is another specialised US federal agency that is part of the US Department of Defense (DOD) and a component of the US Intelligence Community.
It has a similar policy on the name ‘Persian Gulf’.
The NGA produces maps and charts for air and marine navigation, mainly for US military purposes.
It produces cartography and related products covering the entire world.

 Visualization with the GeoGarage platform (NGA nautical raster chart)
 
The NGA maintains a server – namely, the NGA GEOnet Names Server (GNS) – that is the ‘official repository of standard spellings of all foreign place names’ sanctioned by the Board of Geographical Names.
The GNS lists ‘Persian Gulf’ as the only ‘conventional’ name for the body of water in question.
The website containing information on names indicates that ‘the geographic names in this database are provided for the guidance of and use by the Federal Government and for the information of the general public’.

 
‘Sailing Directions Pub. 172 Red Sea and the Persian Gulf’ is a publication by the NGA.
It covers stretches of water from the Suez Canal, the Gulf of Aden and the Arabian Sea to the Gulf of Oman and the Persian Gulf.
Sections 13 through 17 of this work depict the different parts of the Persian Gulf, beginning with ‘the Strait of Hormuz and the entrance to the Persian Gulf’ and ‘the Persian Gulf – Iran – Bushehr to the Shatt al-Arab’.

On the basis of the recognition by the USBGN and GNS of the term ‘Persian Gulf’ for US government use, and on the grounds of long-established domestic and global usage, all US agencies in principle acknowledge the term ‘Persian Gulf’.
In practice, too, it was what all US agencies, media, etc, adhered to unwaveringly.
Thus, ‘Persian Gulf’ has been the official American term since 1917 and in the absence of any explanation from the US government, there’s no logical reason to change it, except as a rather gesture calculated to annoy the Iranians.

 
A 1763 map of the Persian Gulf by the French cartographer Jacques-Nicolas Bellin.
Credit...Library of Congress

The US Navy wavering with the term ‘Persian Gulf’

As US military units were reflagging and escorting Kuwaiti oil tankers at the height of a ‘tanker war’ in 1987 towards the end of the Iran–Iraq War, they began referring to the Gulf in official statements in September 1987 as the ‘Arabian Gulf’.
At the time, a spokesman for the DOD said ‘this usage was adopted out of deference to a number of Arab countries’.

There are also signs indicating that the more a ‘cold war’ between Tehran and Washington set in, the more American officials have tended to distance themselves from the US’s time-honoured recognition of the term ‘Persian Gulf’.
It seems that, increasingly, they began using this issue to bring more pressure to bear on Iran, in parallel with toughening sanctions.

During the Persian Gulf War in 1991–2, ‘Persian Gulf’ was often in the headlines.
Although it has been in use for many years, US Navy commanders in the region, in parallel with the military base rights the US received from some Persian Gulf Arab states, began wavering on Persian Gulf nomenclature mainly during the Iraq war.
 
Navy causes controversy by changing ‘Persian Gulf’ to ‘Arabian Gulf’
source : AllGov

As The Los Angeles Times noted then: “Some US Navy officials, in deference to the Arab partners of the multinational coalition against Iraq, have begun using the “Arabian Gulf” terminology.’
At the same time, they asked that the name be changed to ‘Arabian Gulf’.(p. 60) This request meant to pander to its Arab partners and providers of military bases.
 
Map of the Arabian Gulf countries at the western coast of the Gulf.
Source: (Rehren. T, 2011, p. 2).
 
An early map of Arabian Gulf. 
Source: (Al-Qasimi, 1996. p 41). 
 
The request was put before the USBGN Foreign Names Committee, which carefully studied the matter.
Yet, however interesting under the circumstances, it was turned down.
One argument – which has always been a major principle of the USBGN – emphasised that ‘no country can change a traditional name of a feature whose territory is beyond the sovereignty of a single nation’.
Another argument against the change was ‘the existence of a nearby body of water already named the ‘Arabian Sea’(p. 60).

A US Navy spokesperson, addressing the protests by Iranians, reads as follows: “… [W]e are aware of the long and proud history of the Persian people … We are also well aware of the long history behind the origin of the name of the Persian Gulf … The term ‘Arabian Gulf’ (versus) Persian Gulf is really only applicable to the Navy since its commands in their area would be the only naval forces publishing stories in the region.
In most other respects (nautical charts and publications for example) the historic name of Persian Gulf is used.
We value and respect the partners with whom we serve around the globe, and mean no harm or insult to any people.”

A review of the literature produced by the DOS shows that its officials are still mostly, and perhaps instinctively, loyal to the term with which they have been familiar for many years since their school and college days.
Despite the official position on the use of the term ‘Persian Gulf’ in the State Department and the White House, occasionally and in specific circumstances another term has been used to address a different audience.
Google Maps renames Persian Gulf during nuclear talks
source : Shafaq

Congress and ‘Persian Gulf’


The US Congress uses the name ‘Persian Gulf’ uniformly in legislation such as the ‘Persian Gulf Conflict Education Equity Act’, adopted on 5 February 1991.
In another adopted act, a ‘Persian Gulf veteran’ is defined as ‘a veteran who served on active military, naval, or air service in the Southwest Asia Theatre of operations.’

We may conclude that ‘Persian Gulf’ continues to be the official name recognised by the US official agencies and by US academic, media and cultural establishments.
The US Navy’s position on the usage of the term, as well as some inconsistency exhibited by the DOS, appear to be on account of deteriorating relations with Iran.
This situation has allowed proponents of ‘Arabian Gulf’ to find a more receptive audience within various US administrations, especially where the matter of US forces stationed on Arab soil is concerned.

Links :

Monday, May 19, 2025

Kongsberg Discovery equips year-long research voyage with latest technology

Statsraad Lehmkuhl is one of the world’s largest, oldest and most elegant square-rigged ships still in full operation year-round.
(Image courtesy: One Ocean Expedition)
 
From Hydro

Kongsberg Discovery has played a pivotal role in transforming the 111-year-old Statsraad Lehmkuhl into a modern research vessel for the next leg of the One Ocean Expedition, which set sail from Bergen, Norway, on 11 April.
Measuring nearly 100 metres, the iconic three-masted barque is Norway’s largest sailing ship.
It now carries a comprehensive suite of Kongsberg Discovery technology to support scientific exploration of remote and ecologically significant marine environments, including the storied Northwest Passage.

Among the onboard systems are 75kHz and 300kHz acoustic Doppler current profilers (ADCPs), EK80 echosounders, a sophisticated hydrophone cluster and the Seapath GNSS-aided inertial navigation system.
Data captured at sea will be processed and shared daily via Blue Insight, Kongsberg Discovery’s advanced platform for ocean data management and analytics.
Additional equipment includes weather stations, water samplers, situational awareness and motion reference units, plus various sensors designed to expand the vessel’s research capabilities and contribute to a deeper understanding of the world’s oceans.
 

For further details on the route and expedition, see here.
 
Collecting a wealth of data en route

The One Ocean Expedition 2025–2026 is a 12-month voyage encompassing 26 ports across three continents.
It will see a crew featuring seasoned scientists, eager students and key stakeholders crossing the Atlantic Ocean, the Mediterranean, the Arctic, the Pacific and the Caribbean.
En route, the team will collect a wealth of data to help ascertain ocean health, monitor marine ecosystems and assess the impact of climate change, building both knowledge and awareness of pressing issues.

“It is a great honour to be supporting this crucial expedition with our cutting-edge solutions,” says Martin Wien Fjell, president of Kongsberg Discovery.
“The ship will work as a unique data acquisition platform, empowering insights in often remote and little-understood environments, such as the Northwest Passage, while gathering invaluable information about the broader state of ocean health.

“Our systems are perfectly suited to the tasks ahead, performing with proven reliability, optimal precision and high-quality results in even the most demanding conditions. We’re looking forward to setting sail, while also helping the students set sail on their careers as the next generation of ocean scientists and explorers. We believe major discoveries await.”

Kongsberg Discovery technology is installed throughout Statsraad Lehmkuhl, transforming the 111-year-old ship into a modern research vessel.
(Image courtesy: Kongsberg Discovery)

Technology package

Kongsberg Discovery’s innovations will be put to work on several key assignments, including measuring ocean currents with the ADCP, to help understand how marine life is affected by ocean movements, and recording underwater noise using hydrophones, to ‘listen’ for pollution and monitor marine mammals such as whales.

“The Statsraad Lehmkuhl is an incredible vessel, but to meet the ambitious expedition goals it needed a major technology upgrade,” comments Haakon Vatle, CEO and expedition leader, The One Ocean Expedition.
“We’re immensely grateful to Kongsberg Discovery and the Kongsberg Group for their commitment to tailoring a technology package that will allow us to shine light on the depths and unlock a level of understanding that, we hope, can benefit the entire world.”

The One Ocean Expedition sets sail during One Ocean Week in Bergen, calling in at ports including Reykjavik, Nuuk (Greenland), Cambridge Bay (Canada), Seattle, La Paz (Mexico), Cartagena (Columbia), Cadiz and Dublin.
During its stop in Nice, France, vessel team members will participate in the 2025 UN Ocean Conference.
Statsraad Lehmkuhlwill return to Bergen in April 2026, in time for next year’s One Ocean Week.

Links :
  • Marine Technology News : Kongsberg Discovery Technology Sets Sail On One Ocean Expedition Research Voyage

Sunday, May 18, 2025

SV "Pourquoi pas?". Jean-Baptiste Charcot's oceanographic ship.


 
Last voyage of the Pourquoi-Pas (1936)
Jean-Baptiste Charcot (French polar explorer) and his crew
aboard the Pourquoi-Pas before being lost in Icelandic storm

Saturday, May 17, 2025

Our Planet | Coastal Seas

Experience our planet's natural beauty and examine how climate change impacts all living creatures in this ambitious documentary of spectacular scope.
In this episode: From fearsome sharks to lowly urchins, 90 percent of marine creatures live in coastal waters.
Protecting these habitats is a battle humanity must win.