Category: Earth Observation

Image depicts the sea surface temperature. Image credit: Shep Smithline, GFDL; Chris Hill, MIT. Click to enlarge
Researchers from MIT, NASA’s Goddard Space Flight Center and several other government and academic institutions have created four new supercomputer simulations that for the first time combine mathematical computer models of the atmosphere, ocean, land surface and sea ice.

These simulations are the first field tests of the new Earth System Modeling Framework (ESMF), an innovative software system that promises to improve predictive capability in diverse areas such as short-term weather forecasts and century-long climate-change projections.

Although still under development, groups from NASA, the National Science Foundation, the National Oceanic and Atmospheric Administration (NOAA), the Department of Energy, the Department of Defense and research universities are using ESMF as the standard for coupling their weather and climate models to achieve a realistic representation of the Earth as a system of interacting parts.

ESMF makes it easier to share and compare alternative scientific approaches from multiple sources; it uses remote sensing data more efficiently and eliminates the need for individual agencies to develop their own coupling software.

“The development of large Earth system applications often spans initiatives, institutions and agencies, and involves the geoscience, physics, mathematics and computer science communities. With ESMF, these diverse groups can leverage common software to simplify model development,” said NASA’s Arlindo da Silva, a scientist in Goddard’s Global Modeling and Assimilation Office.

The newly completed field tests, known as interoperability experiments, show that the new approach can be successful. Although most of the experiments would require exhaustive tuning and validation to be scientifically sound, they already show that ESMF can be used to assemble coupled applications quickly, easily and with technical accuracy.

The MIT experiment combines an atmosphere-land-ice model from NOAA’s Geophysical Fluid Dynamics Laboratory with an MIT ocean-sea ice model known as MITgcm (http://mitgcm.org/). This may ultimately bring new insights into ocean uptake of carbon dioxide and other atmospheric gases and information on how this process affects climate. Christopher Hill, principal research scientist in the MIT Department of Earth, Atmospheric and Planetary Sciences, and a member of the MIT Climate Modeling Iniatiative, led development of the software at MIT.

The ESMF research team plans to release the software to the scientific community via the Internet later this month.

Original Source: MIT News Release

Artist’s conception of the Earth’s inner layers. Image credit: S. Jacobsen, M. Wysession, and G. Caras. Click to enlarge
Recently, seismologists have observed that the speed and direction of seismic waves in Earth?s lower mantle, between 400 and 1,800 miles below the surface, vary tremendously. ?I think we may have discovered why the seismic waves travel so inconsistently there,? stated Jung-Fu Lin.* Lin was with the Carnegie Institution?s Geophysical Laboratory at the time of the study and lead author of the paper published in the July 21, issue of Nature. ?Until this research, scientists have simplified the effects of iron on mantle materials. It is the most abundant transition metal in the planet and our results are not what scientists have predicted,? he continued. ?We may have to reconsider what we think is going in that hidden zone. It?s much more complex than we imagined.?

The crushing pressures in the lower mantle squeeze atoms and electrons so closely together that they interact differently from under normal conditions, even forcing spinning electrons to pair up in orbits. In theory, seismic-wave behavior at those depths may result from the vice-gripping pressure effect on the electron spin-state of iron in lower-mantle materials. Lin?s team performed ultra high-pressure experiments on the most abundant oxide material there, magnesiow?stite (Mg,Fe)O, and found that the changing electron spin states of iron in that mineral drastically affect the elastic properties of magnesiow?stite. The research may explain the complex seismic wave anomalies observed in the lowermost mantle.

As co-author of the study Viktor Struzhkin elaborated: ?This is the first study to demonstrate experimentally that the elasticity of magnesiow?stite significantly changes under lower-mantle pressures ranging from over 500,000 to 1 million times the pressure at sea level (1 atmosphere). Magnesiow?stite, containing 20% iron oxide and 80% magnesium oxide, is believed to constitute roughly 20% of the lower mantle by volume. We found that when subjected to pressures between 530,000 and 660,000 atmospheres the iron?s electron spins went from a high-spin state (unpaired) to a low-spin state (spin-paired). While monitoring the spin-state of iron, we also measured the rate-of-change in the volume (density) of magnesiow?stite through the electronic transition. That information enabled us to determine how seismic velocities will vary across the transition.?

?Surprisingly, bulk seismic waves travel about 15% faster once the electrons of iron are spin-paired in the magnesium-iron oxide,? commented co-author Steven Jacobsen. ?The measured velocity jump across the transition might, therefore, be detectable seismically in the deep mantle.? The experiments were conducted inside a diamond-anvil pressure cell using the intense X-ray light source at the nation’s third-generation synchrotron source, Argonne National Laboratory near Chicago.

?The mysterious lower mantle region can?t be sampled directly. So we have to rely on experimentation and theory. Since what happens in Earth?s interior affects the dynamics of the entire planet, it?s important for us to find out what is causing the unusual behavior of seismic waves in that region,? stated Lin. ?Up to now, earth scientists have understood Earth?s interior by only considering pure oxides and silicates. Our results simply point out that iron, the most abundant transition metal throughout the entire Earth, gives rise to very complex properties in that deep region. We look forward to our next experiments to see if we can refine our understanding of what is happening there,? he concluded.

Original Source: Carnegie Institution News Release

Resolute Bay seen by the Hyperion instrument aboard Earth Observing-1. Image credit: NASA. Click to enlarge
Spring thaw in the Northern Hemisphere was monitored by a new set of eyes this year — an Earth-orbiting NASA spacecraft carrying a new version of software trained to recognize and distinguish snow, ice, and water from space.

Using this software, the Space Technology 6 Autonomous Sciencecraft Experiment autonomously tracked changes in the cryosphere, the section of Earth that is frozen, and relayed the information and images back to scientists.

The software, developed by engineers at NASA’s Jet Propulsion Laboratory, Pasadena, Calif., controls the Earth Observing-1 spacecraft. NASA’s Goddard Space Flight Center, Greenbelt, Md, manages the satellite. The software has taken more than 1,500 images of frozen lakes in Minnesota, Wisconsin, Quebec, Tibet and the Italian Alps, along with sea ice in Arctic and Antarctic bays.

While other spacecraft only capture images when they receive explicit commands to do so, for the last year Earth Observing-1 has been making its own decisions. Based on general guidelines from scientists, the spacecraft automatically tracks events such as volcano eruptions, floods and ice formation. The most recent software upgrade allows the spacecraft to accurately recognize cryosphere changes such as ice melting.

Previously, scientists spent several months developing software for Earth Observing-1 to detect changes in snow, water and ice. The new software is capable of learning by itself, and it took only a few hours for scientists to train it to recognize cryosphere changes. In fact, the new software has learned to classify the images so well that scientists plan to use it for the remainder of the mission.

“This new software is capable of a rudimentary form of learning, much the way a child learns the names of new objects,” said Dominic Mazzoni, the JPL computer scientist who developed the software. “Instead of programming the software using a complicated series of commands and mathematical equations, scientists play the role of a teacher, repeatedly showing the computer different images and giving feedback until it has correctly learned to tell them apart.”

On Earth Observing-1, the software searches for specific cryospheric events and reprograms the spacecraft to capture additional images of the event.

“The software has exceeded all of our expectations,” said Dr. Steve Chien, JPL principal investigator for the Autonomous Sciencecraft Experiment. “We have demonstrated that a spacecraft can operate autonomously, and the software has taken literally hundreds of images without ground intervention.”

Similar software has been used to distinguish between different types of clouds in images captured by JPL’s Multi-angle Imaging SpectroRadiometer, an instrument on NASA’s Terra spacecraft. Automatically identifying types of clouds from space will help scientists better understand Earth’s global energy balance and predict future climate trends.

Future versions of the software also might be used to track dust storms on Mars, search for ice volcanoes on Jupiter?s moon Europa, and monitor activity on Jupiter’s volcanically active moon Io. NASA’s New Millennium Program developed both the satellite and the software. The program is responsible for testing new technologies in space.

For more information on the Autonomous Sciencecraft Experiment on the Internet, visit: http://ase.jpl.nasa.gov .

For more information on the New Millennium Program on the Internet, visit: http://nmp.jpl.nasa.gov .

For information about the Earth Observing-1 spacecraft on the Internet, visit: http://eo1.gsfc.nasa.gov .

Original Source: NASA News Release

Artist illustration of NASA satellite measuring sea levels. Image credit: NASA/JPL. Click to enlarge.
For the first time, NASA has the tools and expertise to understand the rate at which sea level is changing, some of the mechanisms that drive those changes and the effects that sea level change may have worldwide.

“It’s estimated that more than 100 million lives are potentially impacted by a one-meter (3.3-foot) increase in sea level,” said Dr. Waleed Abdalati, head of the Cryospheric Sciences Branch at NASA’s Goddard Space Flight Center, Greenbelt, Md. “When you consider this information, the importance of learning how and why these changes are occurring becomes clear,” he added.

Although scientists have directly measured sea level since the early part of the 20th century, it was not known how many of the observed changes in sea level were real and how many were related to upward or downward movement of the land. Now satellites have changed that by providing a reference by which changes in ocean height can be determined regardless of what the nearby land is doing. With new satellite measurements, scientists are able to better predict the rate at which sea level is rising and the cause of that rise.

“In the last 50 years sea level has risen at an estimated rate of .18 centimeters (.07 inches) per year, but in the last 12 years that rate appears to be .3 centimeters (.12 inches) per year. Roughly half of that is attributed to the expansion of ocean water as it has increased in temperature, with the rest coming from other sources,” said Dr. Steve Nerem, associate professor, Colorado Center for Astrodynamics Research, University of Colorado, Boulder.

Another source of sea level rise is the increase in ice melting. Evidence shows that sea levels rise and fall as ice on land grows and shrinks. With the new measurements now available, it’s possible to determine the rate at which ice is growing and shrinking.

“We’ve found the largest likely factor for sea level rise is changes in the amount of ice that covers the Earth. Three-fourths of the planet’s freshwater is stored in glaciers and ice sheets or the equivalent of about 67 meters (220 feet) of sea level,” said Dr. Eric Rignot, principal scientist for the Radar Science and Engineering Section at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “Ice cover is shrinking much faster than we thought, with over half of recent sea level rise due to the melting of ice from Greenland, West Antarctica’s Amundsen Sea and mountain glaciers,” he said.

Additionally, NASA scientists and partner researchers now are able to measure and monitor the world’s waters globally in a sustained and comprehensive way using a combination of satellite observations and sensors in the ocean. By integrating the newly available satellite and surface data, scientists are better able to determine the causes and significance of current sea level changes.

“Now the challenge is to develop an even deeper understanding of what is responsible for sea level rise and to monitor for possible future changes. That’s where NASA’s satellites come in, with global coverage and ability to examine the many factors involved,” said Dr. Laury Miller, chief of the National Oceanic and Atmospheric Administration Laboratory for Satellite Altimetry, Washington, D.C.

NASA works with agency partners such as the National Oceanic and Atmospheric Administration and the National Science Foundation to explore and understand sea level change. Critical resources that NASA brings to bear on this issue include such satellites as:

— Topex/Poseidon and Jason, the U.S. portions of which are managed by JPL, which use radar to map the precise features of the oceans’ surface, measuring ocean height and monitoring ocean circulation;

— Ice, Cloud and Land Elevation Satellite (IceSat), which studies the mass of polar ice sheets and their contributions to global sea level change;

— Gravity Recovery And Climate Experiment (Grace), also managed by JPL, which maps Earth’s gravitational field, allowing us to better understand movement of water throughout the Earth.

Original Source: NASA News Release

Radar satellite view of Istanbul. Image credit: ESA. Click to enlarge.
The city of Istanbul, located astride the eastern edge of Europe and western edge of the Asian continent, shown in an Envisat radar multi-temporal composite image.

What is today Europe’s third largest urban centre has been a major city for the last two thousand years. It has known three different names in that time: Byzantium when it was the gateway to Greek settlements on the Black Sea, Constantinople when it became the capital of the Eastern Roman Empire, then Istanbul when it fell to Muslim invaders in 1453.

In 1919 Istanbul lost its position as capital of Turkey, but remains that country’s leading economic centre. Its population has grown from 2.84 million in 1970 to around ten million today, with settlers flocking from rural areas of Anatolia. Around 30% of all the cars owned in Turkey are in Istanbul.

Urban areas show up as white in this image ? the brightest areas being the most densely built-up. Among the densest is the old town, located on the west side of the city on the Emin?nu Peninsula, below the river estuary known as the Golden Horn. Further west along the coast are the runways of Ataturk International Airport.

Istanbul owes its prosperity to its status as a link between the Balkans, the Middle East and Central Asia, and to the high level of shipping that travels through the narrow Bosporus (Bosphorus) channel dividing Europe and Asia.

Some 48 000 ships pass through the Bosporus annually, three times denser than the Suez Canal traffic and four times as dense as the Panama Canal. Around 55 million tonnes of oil are shipped through here each year. Look closely along the Bosporus and bright points from individual ships can be seen. Also visible are the two bridges connecting the two continents, crossed by at least 45 000 vehicles daily.

Note the chain of islands known as the Princes’ Islands (Kizil Islands) off the east side of Istanbul. The city faces onto the inland Sea of Marmara (Marmara Denizi), which has an area of around 11 350 square kilometres. The Bosporus links the Sea to the Black Sea. Note also Lake Iznik (Iznik Golu) towards the south-east corner of the image.

Because radar images measure surface texture rather than reflected light, there is no colour in a standard radar image.

Instead the colour in this image is due to it being a multitemporal composite, made up of three Advanced Synthetic Aperture Radar (ASAR) images acquired on different dates, with separate colours assigned to each acquisition to highlight differences between them: Red for 31 July 2003, Green for 17 April 2003 and blue for 26 February 2004.

The view was acquired in ASAR Image Mode Precision, with pixel sampling of 12.5 metres.

Original Source: ESA News Release

Changing ozone hole. Image credit: NASA/JPL. Click to enlarge.
Despite near-record levels of chemical ozone destruction in the Arctic this winter, observations from NASA’s Aura spacecraft showed that other atmospheric processes restored ozone amounts to near average and stopped high levels of harmful ultraviolet radiation from reaching Earth’s surface.

Analyses from Aura’s Microwave Limb Sounder indicated Arctic chemical ozone destruction this past winter peaked at near 50 percent in some regions of the stratosphere, a region of Earth’s atmosphere that begins about 8 to 12 kilometers (5 to 7 miles) above Earth’s poles. This was the second highest level ever recorded, behind the 60 percent level estimated for the 1999-2000 winter. Data from another instrument on Aura, the Ozone Monitoring Instrument, found the total amount of ozone over the Arctic this past March was similar to other recent years when much less chemical ozone destruction occurred. So what tempered the ozone loss? The answer appears to lie in this year’s unusual Arctic atmospheric conditions.

“This was one of the most unusual Arctic winters ever,” said scientist Dr. Gloria Manney of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., who led the Microwave Limb Sounder analyses. “Arctic lower stratospheric temperatures were the lowest on record. But other conditions like wind patterns and air motions were less conducive to ozone loss this year.”

While the Arctic polar ozone was being chemically destroyed toward the end of winter, stratospheric winds shifted and transported ozone-rich air from Earth’s middle latitudes into the Arctic polar region, resulting in little net change in the total amount of ozone. As a result, harmful ultraviolet radiation reaching Earth’s surface remained at near-normal levels.

Imagery and an animation depicting the Microwave Limb Sounder and Ozone Monitoring Instrument 2005 Arctic ozone observations may be viewed at:

http://www.nasa.gov/vision/earth/lookingatearth/ozone-aura.html

Extensive ozone loss occurs each winter over Antarctica (the “ozone hole”) due to the extreme cold there and its strong, long-lived polar vortex (a band of winds that forms each winter at high latitudes). This vortex isolates the region from middle latitudes. In contrast, the Arctic winter is warmer and its vortex is weaker and shorter-lived. As a result, Arctic ozone loss has always been lower, more variable and much more difficult to quantify.

This was the first Arctic winter monitored by Aura, which was launched in July 2004. Aura’s Microwave Limb Sounder is contributing to our understanding of the processes that cause Arctic wind patterns to push ozone-rich air to the Arctic lower stratosphere from higher altitudes and lower latitudes. Through Aura’s findings, scientists can differentiate chemical ozone destruction from ozone level changes caused by air motions, which vary dramatically from year to year.

“Understanding Arctic ozone loss is critical to diagnosing the health of Earth’s ozone layer,” said Dr. Phil DeCola, Aura program scientist at NASA Headquarters, Washington. “Previous attempts to quantify Arctic ozone loss have suffered from a lack of data. With Aura, we now have the most comprehensive, simultaneous, global daily measurements of many of the key atmospheric gases needed to understand and quantify chemical ozone destruction.”

Ozone loss in Earth’s stratosphere is caused primarily by chemical reactions with chlorine from human-produced compounds like chlorofluorocarbons. When stratospheric temperatures drop below minus 78 degrees Celsius (minus 108 degrees Fahrenheit), polar stratospheric clouds form. Chemical reactions on the surfaces of these clouds activate chlorine, converting it into forms that destroy ozone when exposed to sunlight.

The data obtained by Aura were independently confirmed by instruments participating in NASA’s Polar Aura Validation Experiment, which flew underneath Aura as it passed over the polar vortex. The experiment, flown on NASA’s DC-8 flying laboratory from NASA’s Dryden Flight Research Center, Edwards, Calif., carried 10 instruments to measure temperatures, aerosols, ozone, nitric acid and other gases. The experiment was carried out in January and February 2005.

Aura is the third and final major Earth Observing System satellite. Aura carries four instruments: the Ozone Monitoring Instrument, built by the Netherlands and Finland in collaboration with NASA; the High Resolution Dynamics Limb Sounder, built by the United Kingdom and the United States; and the Microwave Limb Sounder and Tropospheric Emission Spectrometer, both built by JPL. Aura is managed by NASA’s Goddard Space Flight Center, Greenbelt, Md.

For more information on Aura on the Internet, visit: http://aura.gsfc.nasa.gov/

For more information on the Microwave Limb Sounder on the Internet, visit: http://mls.jpl.nasa.gov/

JPL is managed for NASA by the California Institute of Technology in Pasadena.

Original Source: NASA/JPL News Release

ESA’s Envisat image of iceberg B-15A. Image credit: ESA. Click to enlarge.
The mammoth B-15A iceberg appears poised to strike another floating Antarctic ice feature, a month on from a passing blow that broke off the end of the Drygalski ice tongue. As this Envisat image reveals, this time its target is the ice tongue of the Aviator Glacier.

First discovered in 1955, and named to mark the work done by airmen to open up the Antarctic continent, the Aviator Glacier is a major valley glacier descending from the plateau of Victoria Land along the west side of the Mountaineer Range. It enters the sea at Lady Newnes Bay, where it forms a floating ice tongue that extends into the water for about 25 kilometres.

This Envisat Advanced Synthetic Aperture Radar (ASAR) image was acquired on 16 May 2005 in Wide Swath Mode (WSM), providing spatial resolution of 150 metres across a 400-km swath. ASAR can pierce through clouds and local darkness and is capable of differentiating between different types of ice.

The sensor has been following the movements of B-15A since the beginning of the year, gathering the highest frequency weather-independent dataset of this part of the Ross Sea.

Measuring around 115 kilometres in length with an area exceeding 2500 square kilometres, the B-15A iceberg is the world’s largest free-floating object. It is the largest remaining section of the even larger B-15 iceberg that calved from the Ross Ice Shelf in March 2000 before breaking up into smaller sections.

Since then its B-15A section has drifted into McMurdo Sound, where its presence blocked ocean currents and led to a build-up of sea ice that decimated local penguin colonies, deprived of open waters for feeding. During the spring of this year prevailing currents took B-15A slowly past the Drygalski ice tongue. A full-fledged collision failed to take place, but a glancing blow broke the end off Drygalski in mid-April.

The stretch of Victoria Land coast parallel to B-15A’s current position is unusually rich in wildlife, noted for colonies of Adelie penguins as well as Weddell seals and Skuas. If B-15A were to remain in its current position for any prolonged length of time, the danger is that the iceberg could pin sea-ice behind it, blocking the easy access to open water that local animal inhabitants currently enjoy.

Twin-mode Antarctic observations
Envisat’s ASAR instrument monitors Antarctica in two different modes: Global Monitoring Mode (GMM) provides 400-kilometre swath one-kilometre resolution images, enabling rapid mosaicking of the whole of Antarctica to monitor changes in sea ice extent, ice shelves and iceberg movement.

Wide Swath Mode (WSM) possesses the same swath but with 150-metre resolution for a detailed view of areas of particular interest.

ASAR GMM images are routinely provided to a variety of users including the US National Oceanic and Atmospheric Administration (NOAA) National Ice Centre, responsible for tracking icebergs worldwide.

ASAR imagery is also being used operationally to track icebergs in the Arctic by the Northern View and ICEMON consortia, which provide ice monitoring services as part of the Global Monitoring for Environment and Security (GMES) initiative, jointly backed by ESA and the European Union.

This year also sees the launch of CryoSat, a dedicated ice-watching mission designed to precisely map changes in the thickness of polar ice sheets and floating sea ice.

CryoSat, in connection with regular Envisat ASAR GMM mosaics and SAR interferometry – a technique used to combine radar images to measure tiny centimetre-scale shifts between acquisitions – should answer the question of whether the kind of ice-shelf calving that gave rise to B-15 and its descendants are a consequence of ice sheet dynamics or other factors.

Together they will provide insight into whether such iceberg calving occurrences are becoming more common, as well as improving our understanding of the relationship between the Earth’s ice cover and the global climate.

Original Source: ESA News Release

Envisat image of a plankton bloom of the coast of Spain. Image credit: ESA. Click to enlarge.
A break in the clouds in an Envisat observation of the west coast of Europe this week reveals a striking marine phytoplankton bloom currently dominating the Bay of Biscay.

Phytoplankton are microscopic marine plants that drift on or near the surface of the sea, by far the most abundant type of life found in the ocean. Just like plants on land they employ green-pigmented chlorophyll for photosynthesis – the process of turning sunlight into chemical energy.

While individually microscopic, phytoplankton chlorophyll collectively tints the surrounding ocean waters, providing a means of detecting these tiny organisms from space with dedicated ‘ocean colour’ sensors.

As if dye had been placed in the water, the greenish colour highlights whirls of ocean currents. Floating freely in the water, phytoplankton are sensitive not just to available sunlight but also to local environmental variations such as nutrient levels, temperature, currents and winds. Favourable conditions lead to concentrated ‘blooms’ like the one we see here.

Monitoring phytoplankton is important because they form the base of the marine food web ? sometimes known as ‘the grass of the sea’.

On a local level, out-of-control blooms can devastate marine life, de-oxygenating whole stretches of water, while some species of phytoplankton and marine algae are toxic to both fish and humans. It is useful that fishermen, fish farmers and public health officials know about such events as soon as possible.

Globally, phytoplankton are a major influence on the amount of carbon in the atmosphere, and hence need to be modelled into calculations of future climate change.

Phytoplankton blooms occur frequently at this time of year in the Bay of Biscay. This ‘spring bloom’ takes place as cold, nutrient-rich waters are finally exposed to sufficient sunlight to trigger rapid phytoplankton growth. The bloom is signaling a new cycle of biological production, important for the local fishing industry – the Bay of Biscay being a rich fishery.

Envisat’s Medium Resolution Imaging Spectrometer (MERIS) instrument is optimised for ocean colour detection, but also returns detailed multispectral information on land cover, clouds and atmospheric aerosols.

MERIS acquires continuous daytime observations in Reduced Resolution mode as part of its background mission. This is a detail from a MERIS Reduced Resolution image was acquired on 2 May 2005. The full version, viewable by clicking the high-resolution image, has a spatial resolution of 1200 metres and covers an area of 838 by 2277 km.

Original Source: ESA News Release

Envisat will build up the most detailed map of the entire Earth. Image credit: ESA. Click to enlarge.
The most detailed portrait ever of the Earth’s land surface is being created with ESA’s Envisat environmental satellite. The GLOBCOVER project aims at producing a global land cover map to a resolution three times sharper than any previous satellite map.

It will be a unique depiction of the face of our planet in 2005, broken down into more than 20 separate land cover classes. The completed GLOBCOVER map will have numerous uses, including plotting worldwide land use trends, studying natural and managed ecosystems and modelling climate change extent and impacts.

Envisat’s Medium Resolution Imaging Spectrometer (MERIS) instrument is being systematically used in Full Resolution Mode for the project, acquiring images with a spatial resolution of 300 metres, with an average 150 minutes of acquisitions occurring daily.

The estimate is that up to 20 terabytes of imagery will be needed to mosaic together the final worldwide GLOBCOVER map ? an amount of data equivalent to the contents of 20 million books. The image acquisition strategy is based around regional climate patterns to minimise cloud or snow cover. Multiple acquisitions are planned for some regions to account for seasonal variations in land cover.

Other Envisat sensors will work in synergy with MERIS. The Advanced Synthetic Aperture Radar (ASAR) instrument will be used to differentiate between similar land cover classes, such as wetlands and humid tropical rainforests. And information from the satellite’s Advanced Along Track Scanning Radiometer will be used to correct for atmospheric distortion and to perform ‘cloud masking’, or the elimination of cloud pixels.

An international network of partners is working with ESA on the two-year GLOBCOVER project, which is taking place as part of the Earth Observation Data User Element (DUE).

Participants include the United Nations Environment Programme (UNEP), the Food and Agriculture Organisation (FAO), the European Commission’s Joint Research Centre (JRC), the International Geosphere-Biosphere Programme (IGBP) and the Global Observations of Forest Cover and Global Observations of Land Dynamics (GOFC-GOLD) Implementation Team Project Office.

“UNEP anticipates being able to put the GLOBCOVER map to good use within its programme of assessment and early warning of emerging environmental issues and threats, particularly those of a trans-boundary nature,” said Ron Witt of UNEP. “Changes in land cover patterns, effects of environmental pollution and loss of biodiversity often do not respect national or other artificial boundaries. “An updated view of such problems – or their effects – from interpreted space imagery should offer a large boost to UNEP’s effort to monitor the health of the planet and our changing environment.”

Located at Friedrich-Schiller University in Jena, Germany, the GOFC-GOLD Implementation Team Project Office is responsible for developing international standards and methodology for global observations, and is advising GLOBCOVER on classification issues.

The GLOBCOVER classification system is being designed to be compatible with the Global Land Cover map previously produced for the JRC for the year 2000, a one-kilometre resolution map produced from SPOT-4 Vegetation Instrument data and known as GLC 2000.

GLOBCOVER will also serve to update and improve the European Environment Agency’s CORINE 2000 database, a 300-metre resolution land cover map of the European continent based on a combination of updated land cover maps and satellite imagery.

Once worldwide MERIS Full Resolution coverage is achieved, there will actually be two GLOBCOVER maps produced. The first, GLOBCOVER V1, will be produced automatically by mosaicking images together in a standardised way.

The JRC is then utilising its GLC2000 experience to produce the more advanced GLOBCOVER V2 in the second year, taking a regionally-tuned approach to the data. Some 30 teams worldwide will participate in analysing and validating GLOBCOVER products.

Acquired in a standardised 15 bands, the MERIS images are going to be processed with an upgraded algorithm that includes an ortho-rectification fool, correcting for altitude based on a digital elevation model (DEM) derived from the Radar Altimeter-2 (RA-2), another Envisat instrument.

Original Source: ESA News Release

Rosetta’s view of Earth, taken during its March 2005 flyby. Image credit: ESA. Click to enlarge.
ESA?s comet chaser mission Rosetta took infrared and visible images of Earth and the Moon, during the Earth fly-by of 4/5 March 2005 while on its way to Comet 67P/Churyumov-Gerasimenko.

These images, now processed, are part of the first scientific data obtained by Rosetta. ?The Earth fly-by represented the first real chance to calibrate and validate the performance of the Rosetta?s instruments on a real space object, to make sure everything works fine at the final target,? said Angioletta Coradini, Principal Investigator for the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument.

?Although we were just calibrating VIRTIS during the Earth fly-by last month, we obtained images of Earth and the Moon which have a high scientific content,? she added.

On 4 and 5 March, before closest approach to Earth and from a distance of 400 000 kilometres from our Moon, Rosetta?s VIRTIS took these images with high resolution in visible and infrared light. In these images, only a small portion of the Moon surface was illuminated (between 19% and 32%).

The spectral analysis (chemical ?finger-printing?) gives indications of the mineralogical differences between highlands and ?seas? or ?maria?. For instance, it was possible to see marked differences in the abundance of two kinds of rocks known as pyroxene and olivine.

On 5 March, after the closest approach to Earth, VIRTIS then took a series of high-resolution images of our planet in visible and infrared light from a distance of 250 000 kilometres. Only 49% of the Earth surface was visible from Rosetta.

Once at Comet 67P/Churyumov-Gerasimenko in 2014, VIRTIS will be used to determine the composition and the nature of the solid nucleus and the gases present in the comet?s coma.

In combination with the other Rosetta instruments, it will also help the selection of the ?touchdown? site for the Rosetta lander Philae.

Before then, Rosetta will make more cosmic loops to reach the comet, and its instruments will collect new data about planets, asteroids and comets. The next encounter with Earth is planned for November 2007.

VIRTIS as been developed by a large consortium of European scientists, with major contribution by Italy, France and Germany.

Original Source: ESA News Release