Mobile version

Altimetry and buoys

(Source: Météo France/CLS, 2002)

At first sight, using in-situ sensors like drifting buoys in combination with altimetry data might seem like overkill. However, both sources of data complement one another very well, each yielding unique information. For example, in-situ measurements validate altimetry data while sea surface heights measured by satellite altimetry help to deploy buoys more precisely.

Drifting buoys-floats with a floating anchor suspended 15 meters below the surface-are used to track surface currents. They are also useful for meteorologists, since a barometer or wind-measuring device can be fitted to them. Wind data collected by buoys are used to calculate the current due to wind (Ekman current) and, at a larger scale, the current due to the Earth's rotation (geostrophic currents).

 

 

 

 

Sea level anomalies and trajectories of drifting buoys tracked by Argos in the North Atlantic, in a zone where there are no major currents. This diagram shows how the buoys tend to follow eddies. The effect of tides is also clearly visible in the small looping patterns (in particular on the plot farthest north) (see animation, 5.9 Mb).
(Credits Météo France/CLS)

Sea level anomalies and trajectories of drifting buoys tracked by Argos (see animation, 3.7 Mb). The buoys mainly follow the Antarctic Circumpolar Current, despite circling in places due mostly to eddies. According to the data, these buoys must have all lost their floating anchor between May 13 and May 25, 2001. It is odd that they continued to follow the current and eddies.
(Credits Météo France/CLS).

 

Sea level anomalies and trajectories of drifting buoys tracked by Argos in the North Atlantic, west of Ireland. These buoys have been "trapped" inside eddies, which are clearly visible as peaks and valleys in sea level anomaly maps (see animation, 1 Mb).
(Credits Météo France/CLS).

 

Sometimes, drifting buoys can be "trapped" in an eddy and circle it in one direction or the other, depending on whether the eddy forms a peak or valley in the ocean surface, and depending on the hemisphere (see A turbulent sea and Current relief). This trapping of drifting buoys collecting meteorological readings proves useful, since the buoys stay in the same place. The advantage of drifting buoys over moored buoys is that they are cheap to produce and deploy. One drawback, however, is that they are sometimes washed up on the shore. Eddies compensate for this natural tendency.


Until now, buoys became trapped in eddies by pure chance. In future, operational oceanography, especially near-real-time altimetry data (from Ssalto/Duacs) and ocean forecasts (Mercator), will make it possible to deploy buoys inside eddies detected by altimetry.

 

 

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!