February 2016 :
With the successful launch of the Sentinel-3 satellite today, February 17th in Australian time,
it's a new era starting for ocean satellite altimetry.
With its 27 day repeat cycle Sentinel-3 brings back a capability
occupied by the European ENVISAT until 2010 and bridged over by the Indian-French SARAL/Altika the last few years.
In effect this kind of orbit complements nicely the Jason series to deliver higher spatial coverage of the ocean dynamics.
But today was the launch of Sentinel-3A ahile Sentinel-3B to be launched in 2017 will probably go on an interleave orbit,
doubling the spatial coverage of the Sentinel-3 within the 27 day repeat cycle. This new era doesn't only bring more operational
and robust observations of the sea level, not only it adds higher spatial coverage of the ground tracks.
It's also the start of a new technological step with a systematic Synthetic Aperture Radar mode use over the oceans.
This means the along track sampling comes down from the typical 7km to the 1km mark and also it can operate with maintained
quality much closer to the coasts. We are looking forward to test and use these new systematic high quality data.
From now on, most planned altimetry missions will have this SAR mode capability (Sentinel-3, Sentinel-6/Jason-CS)
or even SAR interferometric (i.e. high resolution sea surface height mapping) capability (SWOT).
(See : eumetsat-Sentinel3)
January 2016 :
Happy New Year. With the successful launch of the Jason-3 satellite today, January 18th in Australian time, the sea level record is promised to continue properly. We are looking forward to Sentinel-3A to launch in the coming weeks. (See : http://www.nesdis.noaa.gov/jason-3 , #Jason3)
December 2015 :
After being postponed earlier this year, the Jason-3 satellite is now planned to launch in January 2016.
See : http://www.nesdis.noaa.gov/jason-3/ Also, the European Copernicus programme is planning the first Sentinel-3 satellite (Sentinel-3A) which hosts a new generation of dual frequency altimeters capable of higher resolution on the ground and able to capture accurate sea level measurements. It has a 27 day repeat orbit, that is almost 3 times the Jason series.
It means that it will have roughly 3 times less temporal resolution and 3 times more spatial coverage.
With the sentinel-3B twin to be launched in 2017 the coverage should increase again meeting many more sea level applications requirements (closer to the coast and denser coverage in space). See details at : http://www.eumetsat.int/website/home/Satellites/FutureSatellites/CopernicusSatellites/Sentinel3/index.html
September 2015 :
The World Meteorological Orgnaization releases its 5 year summary. see : http://www.wmo.int.
click here to access older news
The SEA LEVEL RISE :
We love the coast. Coastal regions, particularly some
low-lying river deltas, have very high population densities. In excess
of 150 million people live within 1 metre of high tide level, and 250
million within 5 metres of high tide. There are billions of dollars invested
in coastal infrastructure immediately adjacent to the coast. Many of
the world's mega cities (populations of many millions) are on the coast.
The Oceans are changing. Many observations show that the ocean
has been changing over the last several decades. One aspect of this is a warming
ocean resulting in increase of ocean volume through thermal expansion.
There has also been addition of water from glacier and ice sheets and changes in
storage of water on or in the land (e.g. retention of water in man-made dams and
extraction of water from aquifers). These together result in changes in sea level.
An issue of the journal Science has focused on a number of aspects of ocean change,
including sea-level rise. You can view the full-text version of the editorial
A (pdf) reprint of this editorial can be obtained from
This sea-level rise is a response to increasing concentrations of greenhouse
gases in the atmosphere and the consequent changes in the global climate.
Sea-level rise contributes to coastal erosion
and inundation of low-lying coastal regions, particularly during extreme
sea level events. It also leads to saltwater intrusion into aquifers,
deltas and estuaries. These changes impact on coastal ecosystems, water
resources, and human settlements and activities. Regions at most risk
include heavily populated deltaic regions, small islands (especially
coral atolls), and sandy coasts backed by major coastal developments.
On this web site, we attempt to bring together information on sea level
rise and its causes. We also include our estimates of global and regional sea level, links
to other web pages and data sets and a list of our publications.
Photos: Bruce Miller, 2006
Global Mean Sea Level (GMSL) - 1880 to the end of 2014
Our most recent estimate of changes in global averaged sea level since 1993 are estimated from satellite altimeter data (red) and since 1880 by combining in situ sea level data from coastal tide gauges and the spatial patterns of variability determined from satellite altimeter data (blue).
Note that error bars have not been shown for the altimeter data (red curve) for clarity, but are about ±5 mm.
Note also that the error bars on the tide gauge-based estimate get larger in the last few years. This is because the number of gauges going in to the estimate drops off for the last couple of years because of delays getting the most recent data into the PSMSL archive, which is where we get this data from. This is simply due to the the time it takes the various national archives to compile and submit the data.
CLICK HERE to download a print-quality
pdf of this figure.