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Scientists
"Concerned" Ozone layer over Europe dwindling
-European Space Agency
2
December 1999
PARIS - The ozone layer over Britain, Belgium, the Netherlands and Scandinavia has dwindled to worrying levels nearly as low as those found in the Antarctic, the European Space Agency
(ESA) said Thursday.
Measurements taken in the Netherlands showed local ozone levels were some two-thirds below the norm for this time of year, confirming the abnormally low levels detected over northwest Europe this week, ESA said in a statement.
The ozone layer, high up in the atmosphere, shields Earth from much of the sun's harmful ultraviolet rays. A gradual thinning due to emissions of damaging man-made chemicals has increased the occurrence of skin cancer and other illnesses related to over-exposure to ultraviolet rays, scientists say.
The damage to the ozone layer is worst over Antarctica where a hole about twice the size of China and more than two-and-a-half times the
scope of Europe has
developed.
TOMS Observes Low Ozone Event in
Northern Hemisphere-NASA
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A NASA Goddard Space Flight
Center satellite has observed the lowest value of ozone ever seen in the
Northern Hemisphere since satellites first began ozone measurements in
1978. The measurement was obtained on November 30, 1999 using the Total
Ozone Mapping Spectrometer (TOMS) instrument aboard NASA's Earth Probe
(TOMS-EP) satellite.
"This is an
extremely low measurement of ozone for the Northern Hemisphere," said
Dr. Richard McPeters, Principal Investigator for Earth Probe TOMS
The measurement showed
165 Dobson Units (DU) over the North Sea between Scotland and Norway on
November 30, 1999.
The previous low value
of 167 DU was observed in the same region on October 30, 1985. The lowest
values of ozone in the Northern Hemisphere are typically seen in the late
fall period. However, these low northern values rarely drop below 180 DU.
"A combination of
stratospheric and tropospheric weather systems can occasionally create
these extreme low ozone events," said Dr. Paul A. Newman of the NASA
Goddard Space Flight Center. "We understand that dynamics can cause
these low ozone events, but we're unsure why this event set a new record
low value."
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November
30, 1999
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TOMS
Satellite
December
2, 1999
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The NASA images also indicate
that the ozone event was also forming along the Eastern Seaboard over the United States
and Canada on November 26,1999
but moved towards Europe over the next few days. The ozone levels also dropped
over the Western United States as observed from these images.
Images from Earth Probe TOMS
Satellite
(Total Ozone Mapping
Spectrometer)
Nov
26, 1999
Nov 26,1999 Ozone Hole formation
enlarged view
NASA
TOMS images and San Francisco
State University Jet Stream Maps
The
NASA TOMS images show that the ozone hole started forming over The United States
and Canada as early as November 21, 1999. The upper wind images indicate the
ozone hole formation was moved towards Europe over the next several days
resulting in the formation occurring over Europe.
The
Canadian Environment images
from Nov 20- Dec 2,1999 indicate
that the ozone hole was also forming along the Eastern Seaboard over the United States
and Canada . The ozone levels also dropped
over the Western United States as observed from these images. The total ozone
maps for the northern hemisphere are based on near-real time NASA Earth Probe
Total Ozone Mapping Spectrometer (TOMS) gridded satellite data available from
the NASA TOMS home page and on
ground-based measurements provided by Environment Canada and by
the Russian Central Aerological Observatory. If available, other
ground-based total ozone observations are also used.
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