Mobile version

Variations on MDT

Lively Data : July 13, 2005

We saw last month (cf "Kuroshio and Gulf Stream") ocean circulation in the North Pacific and North Atlantic areas by mapping variance of Sea Level Anomalies (SLA).

Basically, choice of SLA - instead of Absolute Dynamic Topography (ADT)- is due to its availability in low resolution: otherwise computing variance in high resolution for a large area over several year is too long for the LAS. And by definition, at a given date:


For example, here are three maps plotted with LAS on December 8, 2004, respectively dynamic topography, sea level anomalies, and errors on these anomalies:

Absolute dynamique topography (merged data), sea level anomalies (merged data) and formal mapping error on SLA on December 8, 2004. Formal mapping error for merged data is accessible when choosing "NRT-SLA" as dataset; this map is also representative of errors made on ADT. We can opt for a map with no contours when writing (0,0,0) in "contour levels" option via "output options"; concerning color scale, it is possible to modify (minimum value, maximum value, step) in "fill levels" still available in "output options".

In the same way, on June 8, 2005:

Absolute dynamique topography (merged data), sea level anomalies (merged data) and formal mapping error on SLA on June 8, 2005.

These series of maps have something in common, it is Mean Dynamic Topography (MDT):

Mean dynamic topography (i.e ADT-SLA) computed respectively on December 8, 2004 and on June 8, 2005.
We used "compare two" option, then we defined suitable datasets and dates, and finally choosed "comparison plot".

MDT represents the stationnary component of total current, so MDT is still the same from a date to another.
Thus, about oceanic variability,


Use the  Live Access Server

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!