Mobile version

Separating planetary waves from eddies

Image of the Month - August 2008

Sea level anomalies Longitude-time diagram (at 27°S in the Pacific), top original, middle filtered so as to remove the eddies (showing planetary waves), bottom filtered so as to remove the planetary waves (showing mostly eddies). Such possibility enable to study the ones without the others -- and vice-versa (Credits Esa).


Eddies and planetary waves as observed in altimetric maps can be similar in their effects on sea surface height: propagation speed and direction, height and spatial scale can fall within a comparable range. To study the ones without the others, or to estimate their relative contributions to sea surface height, you have to separate them.  Research has been undertaken to better understand their respective role, by simulating planetary waves and eddies (planetary waves from theory, eddies from observation) and use those simulations to make a filter that enable to separate in the observations eddies from planetary waves.
Planetary waves were predicted by theory long before they were observed. With altimeters'  precision down to about 2 cm, since Topex/Poseidon, they have been observed continuously and globally since nearly 16 years -- as well as eddies. They both have impacts on the overall climate picture, since planetary waves are producing the El Niño phenomenon, and since eddies can transport heat.

Sea level anomaly maps, top modelled planetary waves, middle modelled waves plus eddies, bottom output of the filter (eddies removed). The latter enable to check the coherence of the filter (Credits Esa)

See also:

Websites on this subject:

EnglishFrançaisEspañol
Rss feedsContactSitemapPartnersFAQGlossaryLexiconMobile
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

The new 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!