Andrew Yee[_1_]
October 3rd 06, 12:02 AM
ESA News
http://www.esa.int
2 October 2006
Record ozone loss during 2006 over South Pole
Ozone measurements made by ESA's Envisat satellite have revealed the ozone
loss of 40 million tonnes on 2 October 2006 has exceeded the record ozone
loss of about 39 million tonnes for 2000.
Ozone loss is derived by measuring the area and the depth of the ozone hole.
The size of this year's ozone hole is 28 million square km, nearly as large
as the record ozone hole extension during 2000, and the depth of the ozone
hole is around 100 Dobson Units, rivalling the record low ozone values in
1998. This year's record ozone loss was reached because these two
measurements occurred during the same time period. (A Dobson unit is a unit
of measurement that describes the thickness of the ozone layer in a column
directly above the location being measured.)
"Such significant ozone loss requires very low temperatures in the
stratosphere combined with sunlight. This year's extreme loss of ozone can
be explained by the temperatures above Antarctica reaching the lowest
recorded in the area since 1979," ESA Atmospheric Engineer Claus Zehner
said.
Ozone is a protective layer found about 25 kilometres above us mostly in the
stratospheric stratum of the atmosphere that acts as a sunlight filter
shielding life on Earth from harmful ultraviolet rays. Over the last decade
the ozone level has lowered by about 0.3% per year on a global scale,
increasing the risk of skin cancer, cataracts and harm to marine life.
The thinning of the ozone is caused by the presence of pollutants in the
atmosphere such as chlorine, originating from man-made pollutants like
chlorofluorocarbons (CFCs), which have still not vanished from the air
despite being banned under the Montreal Protocol (1987).
During the southern hemisphere winter, the atmospheric mass above the
Antarctic continent is kept cut off from exchanges with mid-latitude air by
prevailing winds known as the polar vortex. This leads to very low
temperatures, and in the cold and continuous darkness of this season, polar
stratospheric clouds are formed that contain chlorine.
As the polar spring arrives, the combination of returning sunlight and the
presence of polar stratospheric clouds leads to splitting of chlorine
compounds into highly ozone-reactive radicals that break ozone down into
individual oxygen molecules. A single molecule of chlorine has the potential
to break down thousands of molecules of ozone.
The ozone hole, first recognised in 1985, typically persists until November
or December, when the winds surrounding the South Pole (polar vortex)
weaken, and ozone-poor air inside the vortex is mixed with ozone-rich air
outside it.
Envisat, the largest Earth observation satellite ever built, can localise
ozone depletion and track its changes, enabling the rapid estimation of UV
radiation as well as providing forecasting. The three atmospheric
instruments aboard Envisat are the Scanning Imaging Absorption Spectrometer
for Atmospheric Cartography (SCIAMACHY), the global ozone monitoring by
occultation of stars (GOMOS) sensor and the Michelson interferometer for
passive atmospheric sounding (MIPAS).
In the framework of GMES (Global Monitoring of the Environment and
Security), ESA has backed a project named TEMIS (Tropospheric Emission
Monitoring Internet Service) that provides operational ozone and UV
radiation monitoring based on SCIAMACHY and GOME-1 data. The
ozone-monitoring data provided by these instruments span a time period of 11
years, which will be extended by the upcoming MetOp satellite series.
The first MetOp satellite in the series of three is scheduled to be launched
in 2006 and will assist climate researchers in monitoring ozone levels and
other atmospheric parameters. MetOp -- Europe's first polar-orbiting
satellite and a mission dedicated to operational meteorology -- will include
a next-generation ozone-monitoring instrument called GOME-2, intended to
guarantee continuity of observation of this vital environmental factor well
into the following decades.
"Long-term measurements of ozone levels are of key importance for being able
to monitor the ozone's predicted recovery, which is currently estimated to
take place by around 2060," Zehner said.
[NOTE: Images supporting this release are available at
http://www.esa.int/esaCP/SEMQBOKKKSE_index_1.html ]
More about ...
* Observing the Earth
http://www.esa.int/esaEO/index.html
Related news
* South Polar ozone hole makes big comeback
http://www.esa.int/esaCP/SEM712A5QCE_index_0.html
* Envisat witnesses return of the South Polar ozone hole
http://www.esa.int/esaCP/SEM3B90XDYD_index_0.html
* Near-real time ozone forecasting made possible by Envisat
http://www.esa.int/esaCP/SEMR9DWLDMD_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
Related links
* TEMIS
http://www.temis.nl/
* KNMI
http://www.knmi.nl/
http://www.esa.int
2 October 2006
Record ozone loss during 2006 over South Pole
Ozone measurements made by ESA's Envisat satellite have revealed the ozone
loss of 40 million tonnes on 2 October 2006 has exceeded the record ozone
loss of about 39 million tonnes for 2000.
Ozone loss is derived by measuring the area and the depth of the ozone hole.
The size of this year's ozone hole is 28 million square km, nearly as large
as the record ozone hole extension during 2000, and the depth of the ozone
hole is around 100 Dobson Units, rivalling the record low ozone values in
1998. This year's record ozone loss was reached because these two
measurements occurred during the same time period. (A Dobson unit is a unit
of measurement that describes the thickness of the ozone layer in a column
directly above the location being measured.)
"Such significant ozone loss requires very low temperatures in the
stratosphere combined with sunlight. This year's extreme loss of ozone can
be explained by the temperatures above Antarctica reaching the lowest
recorded in the area since 1979," ESA Atmospheric Engineer Claus Zehner
said.
Ozone is a protective layer found about 25 kilometres above us mostly in the
stratospheric stratum of the atmosphere that acts as a sunlight filter
shielding life on Earth from harmful ultraviolet rays. Over the last decade
the ozone level has lowered by about 0.3% per year on a global scale,
increasing the risk of skin cancer, cataracts and harm to marine life.
The thinning of the ozone is caused by the presence of pollutants in the
atmosphere such as chlorine, originating from man-made pollutants like
chlorofluorocarbons (CFCs), which have still not vanished from the air
despite being banned under the Montreal Protocol (1987).
During the southern hemisphere winter, the atmospheric mass above the
Antarctic continent is kept cut off from exchanges with mid-latitude air by
prevailing winds known as the polar vortex. This leads to very low
temperatures, and in the cold and continuous darkness of this season, polar
stratospheric clouds are formed that contain chlorine.
As the polar spring arrives, the combination of returning sunlight and the
presence of polar stratospheric clouds leads to splitting of chlorine
compounds into highly ozone-reactive radicals that break ozone down into
individual oxygen molecules. A single molecule of chlorine has the potential
to break down thousands of molecules of ozone.
The ozone hole, first recognised in 1985, typically persists until November
or December, when the winds surrounding the South Pole (polar vortex)
weaken, and ozone-poor air inside the vortex is mixed with ozone-rich air
outside it.
Envisat, the largest Earth observation satellite ever built, can localise
ozone depletion and track its changes, enabling the rapid estimation of UV
radiation as well as providing forecasting. The three atmospheric
instruments aboard Envisat are the Scanning Imaging Absorption Spectrometer
for Atmospheric Cartography (SCIAMACHY), the global ozone monitoring by
occultation of stars (GOMOS) sensor and the Michelson interferometer for
passive atmospheric sounding (MIPAS).
In the framework of GMES (Global Monitoring of the Environment and
Security), ESA has backed a project named TEMIS (Tropospheric Emission
Monitoring Internet Service) that provides operational ozone and UV
radiation monitoring based on SCIAMACHY and GOME-1 data. The
ozone-monitoring data provided by these instruments span a time period of 11
years, which will be extended by the upcoming MetOp satellite series.
The first MetOp satellite in the series of three is scheduled to be launched
in 2006 and will assist climate researchers in monitoring ozone levels and
other atmospheric parameters. MetOp -- Europe's first polar-orbiting
satellite and a mission dedicated to operational meteorology -- will include
a next-generation ozone-monitoring instrument called GOME-2, intended to
guarantee continuity of observation of this vital environmental factor well
into the following decades.
"Long-term measurements of ozone levels are of key importance for being able
to monitor the ozone's predicted recovery, which is currently estimated to
take place by around 2060," Zehner said.
[NOTE: Images supporting this release are available at
http://www.esa.int/esaCP/SEMQBOKKKSE_index_1.html ]
More about ...
* Observing the Earth
http://www.esa.int/esaEO/index.html
Related news
* South Polar ozone hole makes big comeback
http://www.esa.int/esaCP/SEM712A5QCE_index_0.html
* Envisat witnesses return of the South Polar ozone hole
http://www.esa.int/esaCP/SEM3B90XDYD_index_0.html
* Near-real time ozone forecasting made possible by Envisat
http://www.esa.int/esaCP/SEMR9DWLDMD_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
Related links
* TEMIS
http://www.temis.nl/
* KNMI
http://www.knmi.nl/