Mobile version

Gibraltar’s internal wave viewed by Swot

Image of the Month - August 2024

Internal waves are gravity waves propagating in the interior of a stratified fluid. They can also be seen on the surface of the fluid, albeit with a smaller amplitude. Straits are places where internal waves can often be observed as a series of concentric circles. These waves are caused by the flow of water (including tidal currents, in this case called internal tides) through the narrower passage, and their friction with the bathymetry - see a demonstration model in a tank. They play an important role in the mixing of ocean waters from the surface to the bottom, and in the redistribution of heat, nutrients, CO2, etc. They can also travel long distances (depending on the geography of the ocean basin), and thus transport heat and nutrients. We have already seen some of them as measured by Swot, probably generated on the bathymetry between Sumatra and the Andaman Islands)
They were quite difficult to detect with conventional altimeters, which only measure at nadir along the track, even though the signal can reach several centimeters in some locations. In straits, the very coastal environment also adds complexity to classical altimetry, while Swot, with its high spatial resolution, has no problem measuring up to the coasts. 
Such waves have been observed in the past by satellites such as Sentinel-1 (Synthetic Aperture Radar), or optical satellites such as Sentinel-2, often in the closely monitored of Gibraltar Strait. The KaRIn instrument aboard Swot (Nasa/Cnes/CSA/UKSA) not only detects them in two dimensions in the Strait of Gibraltar, but also measures the height of internal waves generated on all the world's oceans, systematically at every cycle. This will make it possible to better understand and therefore model them. Several models have been developed in preparation for Swot, to try to correct the sea surface anomalies from internal tides for people who want to focus on meso- and submeso-scale circulation. These will now be compared with the actual measurements, and a second set of improved models will then be proposed to the users and the ground segment, as internal tide corrections. 

See also:

Other web sites on this topic:

EnglishFrançais
Rss feedsContactPartnersFAQLexiconLegal noticePersonal Data Protection PolicyMobile
You must enable cookies in your browser preferences to save the modifications
You are using an older version of Internet Explorer, please update to take full advantage of Aviso+ features

Customize the home page

View all widgets
Reduce display
Public profile
User profile

Select/Deselect widgets

Discover AVISO+

Customizable home, reading tools, products search guide, etc.. Discover step by step the features of the new site AVISO+.

Customizable homepage

This home page is composed of blocks called "widgets".

Rearrange the blocks with a "Click & Drop".

Hide a widget with the cross at the top right. Reset or add a widget with the "wrench" icon. The "User" and "Public" profiles offer a predefined organization.

All the modifications are automatically saved as cookies on your machine so as to enable you to have your own specific AVISO+.

Reading tools

Ease your reading by choosing the page background colour (black/white) and/or by modifying the font size.

Browsing menu and breadcrum trail

To ease your browsing through AVISO+, you can use at any time the main banner items with the interactive submenus or use the browsing menu on the left side of the screen (it is open by default). For more readiness of the page contents, you can fold and unfold the browsing menu by clicking on the tab. At any time you can know where you are thanks to the browsing menu or the breadcrum at the top of the page.

Products search guide

The first submenu of the "Data" banner item leads you to a new search form enabling you to find quickier the product that suits your needs. The list of results is updated according to your selection criteria.

AVISO+ Multimedia

The first submenu of the "Multimedia" banner item leads you to AVISO+ collections of images and videos linked to altimetry and its applications. Have a nice visit!