Mobile version

TOPEX/POSEIDON observes wave enhancement in the Agulhas current

M.L. Gründlingh (NRIO, South Africa)

A number of vessels passing around the tip of the African continent have been damaged by so-called giant waves generated through interaction between the Agulhas Current flowing southwestwards and waves propagating northeastwards.

Significant wave height (SWH) data collected by the TOPEX/POSEIDON satellite were inspected for evidence of wave enhancement in the Agulhas Current. NOAA satellite infrared images provided the position of the Agulhas Current at the time of the TOPEX/POSEIDON satellite overpass, and a time limit of three days between the crossing of the two satellites was applied.

A large number of such wave enhancements were found in the TOPEX/POSEIDON data. As an example, conditions observed in January 1993 are presented. The NOAA image of 2 January 1993 shows the Agulhas Current as a ribbon of warm water flowing southwestwards along the east coast (Figure 1). Off Port Elizabeth and further downstream the linear flow of the current is perturbed by meanders of various dimensions.

Five orbits of TOPEX/POSEIDON (Figure 1) traversing the region of the infra-red image (D96: 4 January; D20: 1 January; D198: 7 January; A183: 7 January; D122: 5 January) show peaks of different amplitudes in the Agulhas Current (Figure 2). Along pass D20 the peak was sharp and located at the inshore edge of the current. Small mismatches (e.g. on 7 January) between the positions of peak enhancement and the "core" of the Agulhas Current can be ascribed to a lateral displacement of the current over the period between the passage of the two satellites. Decreases (attenuations) of the SWH were observed in the area of the eastward flowing Agulhas Return current, where the waves are often aligned with the current.

Rss feedsContactPartnersFAQLexiconMobile
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!