Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


MERIS/AATSR Workshop looks at twin sensors with many uses


Two satellite sensors work better than one for the study of Earth’s oceans, atmosphere and land - that was the message of a major ESA workshop bringing together scientific users of Envisat’s MERIS and AATSR instruments.

Launched three and a half years ago, ESA’s Envisat satellite was built with a synergistic approach in mind. Its ten onboard instruments observe the Earth in a variety of ways, but Envisat’s two most closely aligned sensors are the Medium Resolution Imaging Spectrometer (MERIS) and Advanced Along-Track Scanning Radiometer (AATSR).

Both instruments produce visible-light images of the Earth. MERIS acquires imagery in multispectral bands that return additional environmental information, while AATSR is a radiometer that takes the temperature of the ocean and land to a very high precision, with a dual view design to better characterise the contents of the atmosphere. Their complementary nature means there is a lot of potential in synergistic combination of their data – a possibility explored at this week’s event.

More than 220 European and world scientists gathered at ESRIN, ESA’s European Centre for Earth Observation in Frascati, Italy, to participate in the five-day MERIS/AATSR Workshop. A total of 90 scientific presentations were given during the event, along with 14 keynote speeches, and 65 posters detailing research were on show. The Workshop also hosted training sessions in utilising the software tools used to process images from both sensors - known as the Basic ERS & Envisat AATSR and MERIS (BEAM) toolbox.

Both MERIS and AATSR have a similar history: they were originally designed for operation over the ocean but their high performance has led to an increasing amount of applications for the study of atmospheric constituents and land surfaces.

MERIS was optimised for the observation of ocean colour – used to derive marine phytoplankton and water contents - while AATSR’s main task is to maintain a long-term record of sea surface temperature (SST) commenced by predecessor sensors (ATSR-1 and -2) from 1991 onwards.

The Workshop heard that both MERIS and AATSR are still functioning nominally and are projected to continue working well for another five years. For both sensors, calibration and validation is continuing on an ongoing basis and new processing algorithms and products are being developed.

Professor David Llewellyn-Jones of the Space Research Centre of the University of Leicester - whose research who first originated the (A)ATSR series - reviewed the prospects for synergy with MERIS: "We are at a stage now where we have enough of an understanding of our own problems that we can perhaps look outwards to where we can best combine data from the two sensors."

In processing terms, AATSR’s dual view was judged useful as a means of improved correction for atmospheric or aerosol effects of MERIS data. Conversely, for example, MERIS Full Resolution imagery - with a resolution three times sharper than AATSR - has the potential to better differentiate between pixels of cloud and cold ocean, which currently reduces SST coverage. There was also a lot of scientific potential for this combination of data.


AATSR records sea surface temperature with an accuracy of less than 0.3 K, and Prof. Llewellyn-Jones emphasised the value of the satellite sensor’s long and independently-recorded dataset for the study of climate change. SST is also an important variable for phytoplankton distribution, as blooms are influenced by their local environment.

Phytoplankton charts produced by MERIS exhibit similar patterns to SST maps; picking out currents and eddies such as the Gulf Stream and the Kuroshio Current in Asia. Improved knowledge of patterns of SST and phytoplankton correspondence could help predict blooms on regional and ultimately global levels – phytoplankton populations also being important in climate terms as marine sinks of carbon dioxide.

Ana Silió of the Laboratoire d’Océanographie de Villefranche presented research on the Benguela Current off Africa’s west coast using MERIS and AATSR in combination (together with another ocean ocean sensor SeaWIFS) to model its ’primary productivity’ – the amount of biomass produced via photosynthesis.

MERIS is used operationally for phytoplankton monitoring in a number of regions: a presentation on Harmful Algae Bloom (HAB) detection carried out by the Nansen Environmental and Remote Sensing Center in Norwegian coastal waters recounted that MERIS has now become the primary ocean colour instrument used for this purpose. MERIS data are also being used operationally to derive the quality of coastal water masses as part of the European Union’s Framework Water Directive.

The Workshop also heard how AATSR data was being assimilated in near-real time together with other SST satellite sensors and information sources for the Medspiration project, an ESA-funded effort to represent the temperatures of the seas around Europe as the continent’s contribution to a worldwide project to do the same on a global basis – the Global High Resolution Sea Surface Temperature Pilot Project (GHRSST-PP).


Both sensors are currently the source of a number of atmospheric products: AATSR returns information on cloud properties including aerosol size and optical thickness and depth while MERIS also returns information on the aerosol distribution as well as atmospheric water vapour concentration detection. Combining atmospheric information from both could be useful for atmospheric correction and improving overall data quality.

One presentation by Hermann Mannstein of the German Aerospace Center (DLR) recounted how AATSR is being used to detect the straight clouds from aircraft exhausts over Europe and the North Atlantic, as part of an ESA project called Contrails to examine their environmental impact. MERIS results were being used to validate the AATSR-based algorithm used to spot contrails.


MERIS’s multispectral capability makes it highly adaptable for land cover mapping. A number of MERIS processing algorithms were discussed during the Workshop, including one algorithm developed by the European Commission’s Joint Research Centre (EC-JRC) used to monitor photosynthesis activity, and so track plant growth and health across Europe and the world.

Jadunandan Dash of Southampton University discussed another MERIS product, the MERIS Terrestrial Chlorophyll Index (MTCI) and its use to identify levels of chlorophyll in forests. MTCI has also shown a chlorophyll reduction on vegetation in low-lying coastal zones affected by the tsunami of 26 December 2004. The reduction is due to salt stress, and the plan is to monitor other affected areas to see how the vegetation recovers.

The Workshop also heard presentations on how MERIS Full Resolution mode, with its 300 metre resolution, is being utilised for ESA’s GLOBCOVER project, which is planned to provide the world’s sharpest land cover map.

On land AATSR has been used to maintain a long-term ATSR Fire Atlas, working by night to identify hot spots of fires. One presentation subject was the comparison of ATSR Fire Atlas and MERIS-derived land classifications. A new AATSR Land Surface Temperature (LST) extends the sensor’s applications on land, with a maximum accuracy by night of a few degrees K.

The future

As well as presenting results, the Workshop was also an opportunity for the MERIS and AATSR communities to exchange information with each other and give their inputs to ESA.

Overall the scientists pronounced themselves satisfied with data delivery, particularly MERIS Reduced Resolution data, which is now made available via a rolling internet-based archive. Also MERIS Full Resolution data are now being systematically acquired over land and coastal areas and, in turn, being systematically processed, with the long term intention of being similarly made accessible online.

Mariangela D’Acunto | alfa
Further information:

More articles from Earth Sciences:

nachricht Ice shelf vibrations cause unusual waves in Antarctic atmosphere
25.10.2016 | American Geophysical Union

nachricht Enormous dome in central Andes driven by huge magma body beneath it
25.10.2016 | University of California - Santa Cruz

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Ice shelf vibrations cause unusual waves in Antarctic atmosphere

25.10.2016 | Earth Sciences

Fluorescent holography: Upending the world of biological imaging

25.10.2016 | Power and Electrical Engineering

Etching Microstructures with Lasers

25.10.2016 | Process Engineering

More VideoLinks >>>