Andrew Yee
March 1st 06, 02:49 PM
ESA News
http://www.esa.int
28 February 2006
Four years on, Envisat hailed for its contribution to Earth science
Since its launch in 2002, Envisat, the world's largest and most
sophisticated satellite ever built, has been providing scientists and
operational users with invaluable data for global monitoring and
forecasting -- and the future looks even brighter.
"The Envisat mission has reached its full maturity with the services
provided by the satellite now well established, and the scientific results
based on its data being increasing published," Envisat Mission Manager
Henri Laur said. (For more information on Envisat's achievements, watch
Envisat in Action [10:37])
Envisat, short for environmental satellite, has a unique combination of 10
different instruments which collect data about the Earth's atmosphere,
land, sea and ice -- providing scientists with the most detailed picture
yet of the state of the planet.
Climate change
The Earth's climate is undergoing change more rapidly than at any other
point since the end of the last ice age, 10 000 years ago. Many scientists
and policy makers agree climate change is the biggest problem facing the
planet today.
In order for scientists to understand phenomena linked to climate change,
it is vital to determine how the Earth's processes influence each other.
Envisat is particularly well suited to make this possible because its
instruments collect data simultaneously from the Earth's systems.
Having access to near-continuous data over long periods of time is
important for scientists to identify and analyse long-term climatic trends
and changes. Envisat affords this to scientists by providing continuity of
data initiated in the early 1990s with previous ESA satellites ERS-1 and
ERS-2.
Sea surface temperature is one of the most stable of several geographical
variables which, when determined globally, characterises the state of the
Earth's climate system.
"The global sea temperature has been changing over the years. In fact, it
has been changing ever since records began but there is now evidence there
is a distinctive upward trend in global sea temperature, and this we can
now see from measurements made from Envisat," Professor David
Llewellyn-Jones of the University of Leicester said.
Rising sea levels are also important in the study of global warming. Radar
altimeter (RA-2), one of Envisat's instruments and an enhanced version of
an ERS satellite instrument, makes accurate measurements of the
satellite's height above the sea surface which is then converted to the
sea surface's height. Data acquired by ERS and Envisat show sea levels
have been rising by three millimetres a year since the early 1990s.
Ice monitoring
The recent discovery by Eric Rignot and Pannir Kanagaratnam's -- using
Synthetic Aperture Radar (SAR) data -- that the Greenland glaciers are
melting at a pace twice as fast as previously thought is consistent with
climate change.
Long-term satellite monitoring over Greenland and Antarctica is important
because it provides authoritative evidence of trends and allows scientists
to make predictions.
Envisat's largest instrument, the Advanced Synthetic Aperture Radar
(ASAR), is able to produce high-quality images of these ice sheets because
it is able to see through clouds and darkness -- conditions often found in
polar areas.
Within days of its launch, Envisat captured the disintegration of the
Larsen-B ice shelf in Antarctica. The images surprised scientists because
of the rapid rate at which the shelf broke apart.
"The experience with Larsen shows the glaciers are more vulnerable than
we thought before," Innsbruck University's Professor Helmut Rott said.
Atmospheric monitoring
Envisat circles the globe 14 times a day at a speed of seven kilometres
per second providing continuously updated measurements of the swift
changes occurring in the atmosphere.
The Scanning Imaging Absorption Spectrometer for Atmospheric Chartography
(SCIAMACHY) instrument measures atmospheric trace gases by observing
reflected and scattered sunlight. It has allowed scientists to develop
global mapping by routinely supplying data for global ozone thickness as
well as pollution.
"In 2003, we had 7 000 deaths in Europe from air pollution as a result of
fires. The ability to develop predictive capability, which was in the past
just not feasible, is a new area which will hopefully enable such
disasters to be minimized," Professor John Burrows of the University of
Bremen said.
Earthquake monitoring
Shifts in the movement of the earth's crust are a fearful hazard in many
parts of the world. As part of its 'background mission', Envisat acquired
images of the most seismically active areas of the Earth's land surface
(roughly 15 percent of land).
This data proved invaluable in assessing the earthquake in Bam, Iran, in
December 2003, which resulted in the deaths of 26,000 people.
Envisat's capability through ASAR's radar interferometry -- a technique
which compares two radar images, usually recorded from satellite, taken at
slightly different locations to obtain surface change -- gave scientists a
unique insight into the cause of this tragedy by revealing a blind fault.
According to Oxford University Professor Barry Parson, studying radar
images of the ground around Bam before and after the quake allowed
scientists to construct an interferogram and tell geologists in Iran that
the fault was actually in a different place than previously thought.
Coastal monitoring
Envisat is the only satellite with the capability to provide synergy
between radar and optical data, due to the power and depth of its
instrumentation.
This ability -- made possible by Medium Resolution Imaging Spectrometer
(MERIS) and ASAR -- provides scientists with unique views of coastal
phenomena.
While an optical image observes high-atmosphere cloud structure, a
simultaneous radar observation pierces through the clouds to measure the
sea surface. For instance, when Hurricane Katrina formed in August 2005,
Envisat captured the storm from cloud tops to ocean waves.
Dr. Johnny Johannessen, of the Nansen Environmental and Remote Sensing
Centre in Norway, said displaying the MERIS image next to the ASAR image
gave scientists a more complete understanding of Hurricanes Katrina and
Rita.
"You [could] clearly see the eye of the typhoon or hurricane. You [could]
also see the trajectory of these hurricanes and where they [would]
eventually hit the coastal areas," he said.
Providing almost real-time data
By relaying information through its sister satellite Artemis, Envisat is
able to supply data in almost real time. Faster, more accurate data has
resulted in almost 1 000 scientific projects currently using Envisat, and
the number is rising at a rate of 20 or 30 a month.
Envisat data are also increasingly used for operational applications like
monitoring the sea ice, oil slicks and illegal fisheries, among
others.These applications require the fastest possible access to the
satellite data so that quick decisions can be made.
The need for near real time information is also fundamental for the
continuing development of prediction models, such as forecasts for sea
waves, UV and vegetation stress.
About 250 gigabytes of data products are generated every day by the
Envisat mission -- not only for immediate use, but also for building an
archive for the next generation to use.
Future of Envisat
Envisat was initially intended to stay in orbit for five years. However,
given the overall excellent standing of the satellite, the ESA Ministerial
Council agreed last December in Berlin, Germany, to fund the Envisat
mission until 2010.
"This is a very important decision that was driven by requests from the
Earth Science community and the need to fulfil the needs of the GMES
programme in its early phase.
"In addition to using the funding for satellite operations, it will also
be used, to further improve the services offered to our users, such as
providing even easier access to the data, further improving the quality of
the processors used to interpret the data and supporting the data
re-analysis," Laur said.
"I think we are just seeing the beginning of what Envisat in total will
give us in 2010," Dr. Johannessen said.
Related news
* B-15A collides with Antarctic ice tongue
http://www.esa.int/esaEO/SEMEGLW797E_index_0.html
* Global air pollution map produced by Envisat's SCIAMACHY
http://www.esa.int/esaEO/SEM340NKPZD_index_0.html
* Envisat's rainbow vision detects ground moving at pace fingernails grow
http://www.esa.int/esaEO/SEMLD1W4QWD_index_0.html
* Envisat sees whirling Hurricane Katrina from ocean waves to cloud tops
http://www.esa.int/esaEO/SEMB41A5QCE_index_0.html
* Envisat concludes a busy second year in orbit
http://www.esa.int/esaEO/SEMASD2PGQD_index_0.html
* Envisat celebrates first anniversary in space
http://www.esa.int/esaEO/SEMBYF2A6BD_index_0.html
Related Missions
* Envisat overview
http://www.esa.int/esaEO/SEMWYN2VQUD_index_0_m.html
In Depth
* GMES
http://www.esa.int/esaLP/LPgmes.html
* Data User Element
http://dup.esrin.esa.it
* Earth Observation Market Development (EOMD)
http://www.eomd.esa.int/
* EO Principal Investigator Portal
http://eopi.esa.int/
[NOTE: Images supporting this release are available at
http://www.esa.int/esaEO/SEM7BLMVGJE_index_1.html ]
http://www.esa.int
28 February 2006
Four years on, Envisat hailed for its contribution to Earth science
Since its launch in 2002, Envisat, the world's largest and most
sophisticated satellite ever built, has been providing scientists and
operational users with invaluable data for global monitoring and
forecasting -- and the future looks even brighter.
"The Envisat mission has reached its full maturity with the services
provided by the satellite now well established, and the scientific results
based on its data being increasing published," Envisat Mission Manager
Henri Laur said. (For more information on Envisat's achievements, watch
Envisat in Action [10:37])
Envisat, short for environmental satellite, has a unique combination of 10
different instruments which collect data about the Earth's atmosphere,
land, sea and ice -- providing scientists with the most detailed picture
yet of the state of the planet.
Climate change
The Earth's climate is undergoing change more rapidly than at any other
point since the end of the last ice age, 10 000 years ago. Many scientists
and policy makers agree climate change is the biggest problem facing the
planet today.
In order for scientists to understand phenomena linked to climate change,
it is vital to determine how the Earth's processes influence each other.
Envisat is particularly well suited to make this possible because its
instruments collect data simultaneously from the Earth's systems.
Having access to near-continuous data over long periods of time is
important for scientists to identify and analyse long-term climatic trends
and changes. Envisat affords this to scientists by providing continuity of
data initiated in the early 1990s with previous ESA satellites ERS-1 and
ERS-2.
Sea surface temperature is one of the most stable of several geographical
variables which, when determined globally, characterises the state of the
Earth's climate system.
"The global sea temperature has been changing over the years. In fact, it
has been changing ever since records began but there is now evidence there
is a distinctive upward trend in global sea temperature, and this we can
now see from measurements made from Envisat," Professor David
Llewellyn-Jones of the University of Leicester said.
Rising sea levels are also important in the study of global warming. Radar
altimeter (RA-2), one of Envisat's instruments and an enhanced version of
an ERS satellite instrument, makes accurate measurements of the
satellite's height above the sea surface which is then converted to the
sea surface's height. Data acquired by ERS and Envisat show sea levels
have been rising by three millimetres a year since the early 1990s.
Ice monitoring
The recent discovery by Eric Rignot and Pannir Kanagaratnam's -- using
Synthetic Aperture Radar (SAR) data -- that the Greenland glaciers are
melting at a pace twice as fast as previously thought is consistent with
climate change.
Long-term satellite monitoring over Greenland and Antarctica is important
because it provides authoritative evidence of trends and allows scientists
to make predictions.
Envisat's largest instrument, the Advanced Synthetic Aperture Radar
(ASAR), is able to produce high-quality images of these ice sheets because
it is able to see through clouds and darkness -- conditions often found in
polar areas.
Within days of its launch, Envisat captured the disintegration of the
Larsen-B ice shelf in Antarctica. The images surprised scientists because
of the rapid rate at which the shelf broke apart.
"The experience with Larsen shows the glaciers are more vulnerable than
we thought before," Innsbruck University's Professor Helmut Rott said.
Atmospheric monitoring
Envisat circles the globe 14 times a day at a speed of seven kilometres
per second providing continuously updated measurements of the swift
changes occurring in the atmosphere.
The Scanning Imaging Absorption Spectrometer for Atmospheric Chartography
(SCIAMACHY) instrument measures atmospheric trace gases by observing
reflected and scattered sunlight. It has allowed scientists to develop
global mapping by routinely supplying data for global ozone thickness as
well as pollution.
"In 2003, we had 7 000 deaths in Europe from air pollution as a result of
fires. The ability to develop predictive capability, which was in the past
just not feasible, is a new area which will hopefully enable such
disasters to be minimized," Professor John Burrows of the University of
Bremen said.
Earthquake monitoring
Shifts in the movement of the earth's crust are a fearful hazard in many
parts of the world. As part of its 'background mission', Envisat acquired
images of the most seismically active areas of the Earth's land surface
(roughly 15 percent of land).
This data proved invaluable in assessing the earthquake in Bam, Iran, in
December 2003, which resulted in the deaths of 26,000 people.
Envisat's capability through ASAR's radar interferometry -- a technique
which compares two radar images, usually recorded from satellite, taken at
slightly different locations to obtain surface change -- gave scientists a
unique insight into the cause of this tragedy by revealing a blind fault.
According to Oxford University Professor Barry Parson, studying radar
images of the ground around Bam before and after the quake allowed
scientists to construct an interferogram and tell geologists in Iran that
the fault was actually in a different place than previously thought.
Coastal monitoring
Envisat is the only satellite with the capability to provide synergy
between radar and optical data, due to the power and depth of its
instrumentation.
This ability -- made possible by Medium Resolution Imaging Spectrometer
(MERIS) and ASAR -- provides scientists with unique views of coastal
phenomena.
While an optical image observes high-atmosphere cloud structure, a
simultaneous radar observation pierces through the clouds to measure the
sea surface. For instance, when Hurricane Katrina formed in August 2005,
Envisat captured the storm from cloud tops to ocean waves.
Dr. Johnny Johannessen, of the Nansen Environmental and Remote Sensing
Centre in Norway, said displaying the MERIS image next to the ASAR image
gave scientists a more complete understanding of Hurricanes Katrina and
Rita.
"You [could] clearly see the eye of the typhoon or hurricane. You [could]
also see the trajectory of these hurricanes and where they [would]
eventually hit the coastal areas," he said.
Providing almost real-time data
By relaying information through its sister satellite Artemis, Envisat is
able to supply data in almost real time. Faster, more accurate data has
resulted in almost 1 000 scientific projects currently using Envisat, and
the number is rising at a rate of 20 or 30 a month.
Envisat data are also increasingly used for operational applications like
monitoring the sea ice, oil slicks and illegal fisheries, among
others.These applications require the fastest possible access to the
satellite data so that quick decisions can be made.
The need for near real time information is also fundamental for the
continuing development of prediction models, such as forecasts for sea
waves, UV and vegetation stress.
About 250 gigabytes of data products are generated every day by the
Envisat mission -- not only for immediate use, but also for building an
archive for the next generation to use.
Future of Envisat
Envisat was initially intended to stay in orbit for five years. However,
given the overall excellent standing of the satellite, the ESA Ministerial
Council agreed last December in Berlin, Germany, to fund the Envisat
mission until 2010.
"This is a very important decision that was driven by requests from the
Earth Science community and the need to fulfil the needs of the GMES
programme in its early phase.
"In addition to using the funding for satellite operations, it will also
be used, to further improve the services offered to our users, such as
providing even easier access to the data, further improving the quality of
the processors used to interpret the data and supporting the data
re-analysis," Laur said.
"I think we are just seeing the beginning of what Envisat in total will
give us in 2010," Dr. Johannessen said.
Related news
* B-15A collides with Antarctic ice tongue
http://www.esa.int/esaEO/SEMEGLW797E_index_0.html
* Global air pollution map produced by Envisat's SCIAMACHY
http://www.esa.int/esaEO/SEM340NKPZD_index_0.html
* Envisat's rainbow vision detects ground moving at pace fingernails grow
http://www.esa.int/esaEO/SEMLD1W4QWD_index_0.html
* Envisat sees whirling Hurricane Katrina from ocean waves to cloud tops
http://www.esa.int/esaEO/SEMB41A5QCE_index_0.html
* Envisat concludes a busy second year in orbit
http://www.esa.int/esaEO/SEMASD2PGQD_index_0.html
* Envisat celebrates first anniversary in space
http://www.esa.int/esaEO/SEMBYF2A6BD_index_0.html
Related Missions
* Envisat overview
http://www.esa.int/esaEO/SEMWYN2VQUD_index_0_m.html
In Depth
* GMES
http://www.esa.int/esaLP/LPgmes.html
* Data User Element
http://dup.esrin.esa.it
* Earth Observation Market Development (EOMD)
http://www.eomd.esa.int/
* EO Principal Investigator Portal
http://eopi.esa.int/
[NOTE: Images supporting this release are available at
http://www.esa.int/esaEO/SEM7BLMVGJE_index_1.html ]