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The Ozone Hole 2018
 

Antarctic Situation at 2018 November 23British Antarctic Survey Ozone Bulletin

Antarctic ozone today:  The 2018 ozone hole is nearly over, with only a small remnant remaining, which may persist for another week.  The vortex became unstable in early November leading to a rapid filling of the ozone hole.  The hole is currently still above average size for the decade at 9 million square kilometres, and is much larger than in 2017 or 2016.  The lowest ozone values, around 190 DU, are near Dronning Maud Land.  Amounts are higher, near 400 DU in places over the southern ocean, particularly over South Georgia.  Ozone values are still below the ozone hole threshold of 220 DU across part of the continent, but range from around 190 DU to 370 DU, with the highest values over the Antarctic Peninsula.  There are marked differences between the various satellite ozone measurements and analyses.  The KNMI analysis and TEMIS forecasts are close to the observed values, whereas the Canadian analysis seems largely based on SMOBA data and is clearly at variance with ground based observations.   The atmospheric circulation over the continent is in the process of a spring warming.   Temperatures in the ozone layer are rising and are now above the  -78°C Polar Stratospheric Clouds (PSC) formation threshold.  Temperatures are highest over the Antarctic Peninsula and decline towards the equator .  They are generally still a little below the normal within the polar vortex.  The southern polar vortex has passed its maximum size and is shrinking.  The vortex area is still larger than the decadal mean at around 25 million square kilometres near the centre of the ozone layer.  The area that can form PSCs has declined to zero.  The lower stratosphere has become unstable as is usual as the vortex begins to break up.  The ozone hole will persist for at about another week.

The 2018 ozone hole:  The polar vortex began to form in early May and reached its maximum area in late September at around 34 million square kilometres.  It was a little larger than the decadal mean in size, and was generally of average or above average stability.  PSCs began to form in mid May and the maximum area with potential PSCs was larger than the decadal mean and close to the maximum of the last decade at around 27 million square kilometres.  Ozone hole values below 220 DU were reached in late August, later than in the past couple of years; this was largely due to the stability in the stratosphere this year.  The ozone hole grew rapidly and by its maximum in late September was above the average size for the decade at 24.8 million square kilometres.  The stratosphere became less stable at the end of September, but then returned to stable conditions.  The ozone hole shrank when it was unstable, but stopped shrinking with the return to stability.  It became much less stable in November, with the vortex oscillating between a very elongated form and a more circular form.  Ozone values are rising across the continent, but the ozone hole still covers  around 9 million square kilometres.  When the vortex became less stable the ozone hole became more elongated and South Georgia was at the edge of the ozone hole at times during October and November.  NASA observations show that a minimum ozone amount of 102 DU was reached on October 11 and 12.  Although this is a low value it is not as low as around 1990 to 2000.  Ozone depletion would have been much worse this year without the protection of the Montreal Protocol.

 


https://ozonewatch.gsfc.nasa.gov

Antarctic Situation at 2018 November 12British Antarctic Survey Ozone Bulletin

Antarctic ozone today:  The 2018 ozone hole has passed its maximum extent and ozone values are now on the rise across the continent.  The vortex became unstable in early November resulting in it becoming very elongate, before returning to a more circular state.  The hole is currently (November 4) well above average size for the decade at 19 million square kilometres, and is much larger than in 2017 or 2016.  The lowest ozone values, around 140 DU, are near Dronning Maud Land.  Amounts are higher, over 400 DU in places over the southern ocean, particularly in the Pacific sector.  Ozone values are still below the ozone hole threshold of 220 DU across much of the continent, but range from around 150 DU to 350 DU, with the highest value along the coastal fringes of the Amundsen and Ross Seas and Enderby Land.  There are marked differences between the various satellite ozone measurements and analyses.  The KNMI analysis and TEMIS forecasts are close to the observed values, whereas the Canadian analysis seems largely based on SMOBA data and is clearly at variance with ground based observations.   The atmospheric circulation over the continent is now starting a spring warming.   Temperatures in the ozone layer are rising and are above the  -78°C Polar Stratospheric Clouds (PSC) formation threshold, but some clouds will remain.  Temperatures are highest in a broad ring around 45°S and decline towards the pole, where they are coldest, and to the equator .  They are generally below the normal within the polar vortex.  The southern polar vortex has passed its maximum size.  The vortex area is still larger than the decadal mean at around 27 million square kilometres near the centre of the ozone layer, but is shrinking.  The area that can form PSCs has declined to near zero, but much later than usual over the last decade.  The lower stratosphere has become unstable as is usual as the vortex begins to break up.  The ozone hole will persist for at least another week.

The 2018 ozone hole:  The polar vortex began to form in early May and reached its maximum area in late September at around 34 million square kilometres.  It was a little larger than the decadal mean in size, and was generally of average or above average stability.  PSCs began to form in mid May and the maximum area with potential PSCs was larger than the decadal mean and close to the maximum of the last decade at around 27 million square kilometres.  Ozone hole values below 220 DU were reached in late August, later than in the past couple of years; this was largely due to the stability in the stratosphere this year.  The ozone hole grew rapidly and by its maximum in late September was above the average size for the decade at 24.8 million square kilometres.  The stratosphere became less stable at the end of September, but then returned to stable conditions.  The ozone hole shrank when it was unstable, but stopped shrinking with the return to stability.  It became much less stable in early November, with the vortex becoming very elongated before returning to a more circular form.  Ozone values are rising across the continent, but the ozone hole still covered 19 million square kilometres on November 4.  When the vortex became less stable the ozone hole became more elongated and South Georgia was at the edge of the ozone hole at times during October and November.  NASA observations show that a minimum ozone amount of 102 DU was reached on October 11 and 12.  Although this is a low value it is not as low as around 1990 to 2000.  Ozone depletion would have been much worse this year without the protection of the Montreal Protocol.

Nov. 2, 2018
Ozone Hole Modest Despite Optimum Conditions for Ozone Depletion

The ozone hole that forms in the upper atmosphere over Antarctica each September was slightly above average size in 2018, NOAA and NASA scientists reported today.
 

Colder-than-average temperatures in the Antarctic stratosphere created ideal conditions for destroying ozone this year, but declining levels of ozone-depleting chemicals prevented the hole from as being as large as it would have been 20 years ago.

“Chlorine levels in the Antarctic stratosphere have fallen about 11 percent from the peak year in 2000,” said Paul A. Newman, chief scientist for Earth Sciences at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "This year’s colder temperatures would have given us a much larger ozone hole if chlorine was still at levels we saw back in the year 2000.”

According to NASA, the annual ozone hole reached an average area coverage of 8.83 million square miles (22.9 square kilometers) in 2018, almost three times the size of the contiguous United States. It ranks 13th largest out of 40 years of NASA satellite observations. Nations of the world began phasing out the use of ozone-depleting substances in 1987 under an international treaty known as the Montreal Protocol.

The 2018 ozone hole was strongly influenced by a stable and cold Antarctic vortex — the stratospheric low pressure system that flows clockwise in the atmosphere above Antarctica. These colder conditions — among the coldest since 1979 — helped support formation of more polar stratospheric clouds, whose cloud particles activate ozone-destroying forms of chlorine and bromine compounds.

In 2016 and 2017, warmer temperatures in September limited the formation of polar stratospheric clouds and slowed the ozone hole’s growth. In 2017, the ozone hole reached a size of 7.6 million square miles (19.7 square kilometers) before starting to recover. In 2016, the hole grew to 8 million square miles (20.7 square kilometers).

However, the current ozone hole area is still large compared to the 1980s, when the depletion of the ozone layer above Antarctica was first detected. Atmospheric levels of man-made ozone-depleting substances increased up to the year 2000. Since then, they have slowly declined but remain high enough to produce significant ozone loss.

NOAA scientists said colder temperatures in 2018 allowed for near-complete elimination of ozone in a deep, 3.1-mile (5-kilometer) layer over the South Pole. This layer is where the active chemical depletion of ozone occurs on polar stratospheric clouds. The amount of ozone over the South Pole reached a minimum of 104 Dobson units on Oct. 12 — making it the 12th lowest year out of 33 years of NOAA ozonesonde measurements at the South Pole, according to NOAA scientist Bryan Johnson.

"Even with this year's optimum conditions, ozone loss was less severe in the upper altitude layers, which is what we would expect given the declining chlorine concentrations we’re seeing in the stratosphere," Johnson said.

A Dobson unit is the standard measurement for the total amount of ozone in the atmosphere above a point on Earth's surface, and it represents the number of ozone molecules required to create a layer of pure ozone 0.01 millimeters thick at a temperature of 32 degrees Fahrenheit (0 degrees Celsius) at an atmospheric pressure equivalent to Earth’s surface. A value of 104 Dobson units would be a layer that is 1.04 millimeters thick at the surface, less than the thickness of a dime.

Prior to the emergence of the Antarctic ozone hole in the 1970s, the average amount of ozone above the South Pole in September and October ranged from 250 to 350 Dobson units.

What is ozone and why does it matter?

Ozone comprises three oxygen atoms and is highly reactive with other chemicals. In the stratosphere, roughly 7 to 25 miles (about 11 to 40 kilometers) above Earth’s surface, a layer of ozone acts like sunscreen, shielding the planet from ultraviolet radiation that can cause skin cancer and cataracts, suppress immune systems and damage plants. Ozone can also be created by photochemical reactions between the Sun and pollution from vehicle emissions and other sources, forming harmful smog in the lower atmosphere.

NASA and NOAA use three complementary instrumental methods to monitor the growth and breakup of the ozone hole each year. Satellite instruments like the Ozone Monitoring Instrument on NASA’s Aura satellite and the Ozone Mapping Profiler Suite on the NASA-NOAA Suomi National Polar-orbiting Partnership satellite measure ozone across large areas from space. The Aura satellite’s Microwave Limb Sounder also measures certain chlorine-containing gases, providing estimates of total chlorine levels.

The total amount of ozone in the atmosphere is exceedingly small. All of the ozone in a column of the atmosphere extending from the ground to space would be 300 Dobson units, approximately the thickness of two pennies stacked one on top of the other.

NOAA scientists monitor the thickness of the ozone layer and its vertical distribution above the South Pole by regularly releasing weather balloons carrying ozone-measuring “sondes” up to 21 miles (~34 kilometers) in altitude, and with a ground-based instrument called a Dobson spectrophotometer.

To learn more about NOAA and NASA efforts to monitor ozone and ozone-depleting gases, visit:

https://ozonewatch.gsfc.nasa.gov/

https://www.esrl.noaa.gov/gmd/hats/

Twenty Questions About the Ozone - https://www.esrl.noaa.gov/csd/assessments/ozone/2014/twentyquestions/

https://www.nasa.gov/feature/goddard/2018/ozone-hole-modest-despite-optimum-conditions-for-ozone-depletion

 

Antarctic Situation at 2018 October 29 British Antarctic Survey Ozone Bulletin

Antarctic ozone today:  The 2018 ozone hole has passed its maximum extent and ozone values are slowly beginning to rise across the continent.  Conditions have remained relatively stable through October so far and the hole is currently above average size for the decade at 19 million square kilometres, and is much larger than in 2017 or 2016.  The lowest ozone values, around 130 DU, are broadly over the Pole.  Amounts are higher, over 400 DU in places over the southern ocean, particularly south of Australia.  Ozone values are below the ozone hole threshold of 220 DU across much of the continent, but range from around 130 DU to 350 DU, with the highest value along the coastal fringe south of Australia.  There are marked differences between the various satellite ozone measurements and analyses.  The KNMI analysis and TEMIS forecasts are close to the observed values, whereas the Canadian analysis seems largely based on SMOBA data and is clearly at variance with ground based observations.   The southern polar vortex is just past its maximum size.  The atmospheric circulation over the continent is slowly beginning the transition to spring.   Temperatures in the ozone layer are generally rising but with the temperature still widely below  -78°C Polar Stratospheric Clouds (PSC) are extensive in the central part of the ozone layer over the continent.  Temperatures are highest in a broad ring around 45°S and decline towards the pole, where they are coldest, and to the equator .  They are generally a little below the normal within the polar vortex.  The vortex area is larger than the decadal mean at around 32 million square kilometres near the centre of the ozone layer, but is slowly beginning to shrink.  The area with PSCs present has passed its largest and is shrinking rapidly; it is now around 5 million square kilometres, still above the average for the decade at this time of year.  The lower stratosphere has become a little less stable as is usual as the vortex begins to break up.  The vortex is becoming less circular in shape, and the Falklands and South Georgia may be briefly affected by the ozone hole later in the first week of November.

The 2018 ozone hole:  The polar vortex began to form in early May and reached its maximum area in late September at around 34 million square kilometres.  It was a little larger than the decadal mean in size, and was generally of average or above average stability.  PSCs began to form in mid May and the maximum area with potential PSCs was larger than the decadal mean and close to the maximum of the last decade at around 27 million square kilometres.  Ozone hole values below 220 DU were reached in late August, later than in the past couple of years; this was largely due to the stability in the stratosphere this year.  The ozone hole grew rapidly and by its maximum in late September was above the average size for the decade at 23 million square kilometres.  The stratosphere became less stable at the end of September, but then returned to stable conditions.  The ozone hole shrank when it was unstable, but stopped shrinking with the return to stability.  Ozone values are very slowly beginning to rise across the continent, but the ozone hole still covers 19 million square kilometres.  When the vortex became less stable the ozone hole became more elongated and South Georgia was at the edge of the ozone hole at times during October.


https://ozonewatch.gsfc.nasa.gov

Antarctic Situation at 2018 October 26British Antarctic Survey Ozone Bulletin

Antarctic ozone today:  The 2018 ozone hole has passed its maximum extent and ozone values are slowly beginning to rise across the continent.  Conditions have remained stable through October so far and the hole is currently above average size for the decade at 20 million square kilometres, and is much larger than in 2017 or 2016.  The lowest ozone values, around 130 DU, are between the Antarctic Peninsula and the Pole.  Amounts are higher, over 400 DU in places over the southern ocean, particularly south of Australia.  Ozone values are below the ozone hole threshold of 220 DU across much of the continent, but range from around 130 DU to 350 DU, with the highest value along the coastal fringe south of Australia.  There are marked differences between the various satellite ozone measurements and analyses.  The KNMI analysis and TEMIS forecasts are close to the observed values, whereas the Canadian analysis seems largely based on SMOBA data and is clearly at variance with ground based observations.   The southern polar vortex is just past its maximum size.  The atmospheric circulation over the continent is slowly beginning the transition to spring.   Temperatures in the ozone layer are generally rising but with the temperature still widely below  -78°C Polar Stratospheric Clouds (PSC) are extensive in the central part of the ozone layer over the continent.  Temperatures are highest in a broad ring around 45°S and decline towards the pole, where they are coldest, and to the equator .  They are generally a little below the normal within the polar vortex.  The vortex area is larger than the decadal mean at around 32 million square kilometres near the centre of the ozone layer, but is slowly beginning to shrink.  The area with PSCs present has passed its largest and is beginning to shrink rapidly; it is now around 8 million square kilometres, above the average for the decade at this time of year.  The lower stratosphere has returned to more stable conditions and the rise in temperature within the central portion has stalled.  The vortex is becoming less circular in shape, and the Falklands and South Georgia may be affected by the ozone hole later in the first week of November.

The 2018 ozone hole:  The polar vortex began to form in early May and reached its maximum area in late September at around 34 million square kilometres.  It was a little larger than the decadal mean in size, and was generally of average or above average stability.  PSCs began to form in mid May and the maximum area with potential PSCs was larger than the decadal mean and close to the maximum of the last decade at around 27 million square kilometres.  Ozone hole values below 220 DU were reached in late August, later than in the past couple of years; this was largely due to the stability in the stratosphere this year.  The ozone hole grew rapidly and by its maximum in late September was above the average size for the decade at 23 million square kilometres.  The stratosphere became less stable at the end of September, but then returned to stable conditions.  The ozone hole shrank when it was unstable, but stopped shrinking with the return to stability.  Ozone values are very slowly beginning to rise across the continent, but the ozone hole still covers 20 million square kilometres.  When the vortex became less stable the ozone hole became more elongated and South Georgia was at the edge of the ozone hole at times during October.

Antarctic Situation at 2018 October 19 British Antarctic Survey Ozone Bulletin

Antarctic ozone today:  The 2018 ozone hole has passed its maximum extent and ozone values are slowly beginning to rise across the continent.  Conditions have remained stable in the first half of October and the hole is currently above average size for the decade at 21 million square kilometres, and is much larger than in 2017 or 2016.  The lowest ozone values, below 120 DU, are near the Pole.  Amounts are higher, over 400 DU in places over the southern ocean, particularly in the Pacific sector.  Ozone values are below the ozone hole threshold of 220 DU across most of the continent, but range from around 120 DU to 300 DU.  There are marked differences between the various satellite ozone measurements and analyses.  The KNMI analysis and TEMIS forecasts are close to the observed values, whereas the Canadian analysis seems largely based on SMOBA data and is clearly at variance with ground based observations.   The southern polar vortex is just past its maximum size.  The atmospheric circulation over the continent is slowly beginning the transition to spring.   Temperatures in the ozone layer are generally rising but with the temperature widely below  -78°C Polar Stratospheric Clouds (PSC) are extensive in the central part of the ozone layer over the continent.  Temperatures are highest in a broad ring around 45°S and decline towards the pole, where they are coldest, and to the equator .  They are generally a little below the normal within the polar vortex.  The vortex area is larger than the decadal mean at around 33 million square kilometres near the centre of the ozone layer, but is beginning to shrink.  The area with PSCs present has passed its largest and is beginning to shrink rapidly; it is now around 10 million square kilometres, a bit above the average for the decade at this time of year.  The lower stratosphere has returned to more stable conditions and the rise in temperature has stalled.  The vortex remains roughly circular in shape, however South Georgia is likely to remain on or near the edge of the ozone hole until at least October 26.

Antarctic Situation at 2018 October 8 British Antarctic Survey Ozone Bulletin

Antarctic ozone today:  The 2018 ozone hole has passed its maximum extent and ozone values are beginning to rise across the continent.  The hole is currently close to average size for the decade at 20 million square kilometres, and is larger than in 2017 or 2016.  The lowest ozone values, about 120 DU, are over Halley.  Amounts are higher, over 400 DU in places over the southern ocean, particularly in the Pacific sector.  Ozone values are below the ozone hole threshold of 220 DU across most of the continent, but range from around 120 DU to 350 DU.  There are marked differences between the various satellite ozone measurements and analyses.  The KNMI analysis and TEMIS forecasts are close to the observed values, whereas the Canadian analysis seems largely based on SMOBA data and is clearly at variance with ground based observations.   The southern polar vortex is just past its maximum size.  The atmospheric circulation over the continent is beginning the transition to spring.   Temperatures in the ozone layer are generally rising but with the temperature widely below  -78°C Polar Stratospheric Clouds (PSC) are extensive in the central part of the ozone layer over the continent.  Temperatures are highest in a broad ring around 45°S and decline towards the pole, where they are coldest, and to the equator .  They are generally a little below the normal within the polar vortex.  The vortex area is a little larger than the decadal mean at around 33 million square kilometres near the centre of the ozone layer, but is beginning to shrink.  The area with PSCs present has passed its largest and is beginning to shrink rapidly; it is now around 12 million square kilometres, close to the average for the decade at this time of year.  The lower stratosphere has become much less stable and this is driving the rise in temperature, however for the moment the vortex remains roughly circular in shape.  South Georgia may be affected by the ozone hole from October 11 to 13.

The 2018 ozone hole:  The polar vortex began to form in early May and reached its maximum area in late September at around 34 million square kilometres.  It was a little larger than the decadal mean in size, and was generally of average or above average stability.  PSCs began to form in mid May and the maximum area with potential PSCs was larger than the decadal mean and close to the maximum of the last decade at around 27 million square kilometres.  Ozone hole values below 220 DU were reached in late August, later than in the past couple of years; this was largely due to the stability in the stratosphere this year.  The ozone hole grew rapidly and by its maximum in late September was above the average size for the decade at 23 million square kilometres.  Ozone values are beginning to rise across the continent, but the ozone hole still covers 20 million square kilometres.


 https://ozonewatch.gsfc.nasa.gov

Antarctic Situation at 2018 October 1British Antarctic Survey Ozone Bulletin

Antarctic ozone today:  The 2018 ozone hole has formed and ozone values continue to drop across the continent.  The hole is currently above average size for the decade at 23 million square kilometres.  The lowest ozone values, about 120 DU, are near the South Pole.  Amounts are higher, over 400 DU in places over the southern ocean, particularly in the Pacific and Indian Ocean sectors.  Ozone depletion is increasing, with values below the ozone hole threshold of 220 DU across most of the continent.  Ozone values over the continent range from around 120 DU to 300 DU.  There are marked differences between the various satellite ozone measurements and analyses across the Southern Hemisphere.  The KNMI analysis and TEMIS forecasts are close to the observed values, whereas the Canadian analysis seems largely based on SMOBA data and is clearly at variance with ground based observations.   The southern polar vortex is near its maximum size.  The atmospheric circulation over the continent is still in winter mode.   Temperatures in the ozone layer are generally rising but with the temperature widely below  -78°C Polar Stratospheric Clouds (PSC) are extensive in the central part of the ozone layer over the continent.  Temperatures are highest in a broad ring around 45°S and decline towards the pole, where they are coldest, and to the equator .  They are generally a little below the normal within the polar vortex.  The vortex area is a little larger than the decadal mean at around 34 million square kilometres near the centre of the ozone layer.  The area with PSCs present has passed its largest of around 27 million square kilometres, and has shrunk to around 19 million square kilometres, the largest for a decade at this time of year.  In general the lower stratosphere is of above average stability for the time of year and hence the vortex is roughly circular in shape.

The 2018 ozone hole:  The polar vortex began to form in early May and reached its maximum area in late September at around 34 million square kilometres.  It was a little larger than the decadal mean in size, and was generally of average or above average stability.  PSCs began to form in mid May and the maximum area with potential PSCs was larger than the decadal mean and close to the maximum of the last decade at around 27 million square kilometres.  Ozone hole values below 220 DU were reached in late August, later than in the past couple of years; this was largely due to the stability in the stratosphere this year.  The ozone hole grew rapidly and by late September was above the average size for the decade at 23 million square kilometres.  Ozone depletion is near its maximum for the year.

The Ozone Hole 2018

Antarctic Situation at 2018 September 28British Antarctic Survey Ozone Bulletin

Antarctic ozone today:  The 2018 ozone hole has formed and ozone values continue to drop across the continent.  The hole is currently above average size for the decade at 23 million square kilometres.  The lowest ozone values, about 120 DU, are near the tip of the Antarctic Peninsula.  Amounts are higher, over 400 DU in places over the southern ocean, particularly in the Pacific sector.  Ozone depletion is increasing, with values below the ozone hole threshold of 220 DU across most of the continent.  Ozone values over the continent range from around 120 DU to 320 DU.  There are marked differences between the various satellite ozone measurements and analyses across the Southern Hemisphere.  The KNMI analysis and TEMIS forecasts are close to the observed values, whereas the Canadian analysis seems largely based on SMOBA data and is clearly at variance with ground based observations.   The southern polar vortex is near its maximum size.  The atmospheric circulation over the continent is still in winter mode.   Temperatures in the ozone layer have passed their minimum but with the temperature widely below  -78°C Polar Stratospheric Clouds (PSC) are extensive in the central part of the ozone layer over the continent.  Temperatures are highest in a broad ring around 45°S and decline towards the pole, where they are coldest, and to the equator .  They are generally a little below the normal within the polar vortex.  The vortex area is a little larger than the decadal mean at around 33 million square kilometres near the centre of the ozone layer.  The area with PSCs present has passed its largest of around 27 million square kilometres, and has shrunk to around 18 million square kilometres, larger than the decadal mean.  In general the lower stratosphere is of above average stability for the time of year and hence the vortex is roughly circular in shape.

The 2018 ozone hole:  The polar vortex began to form in early May and reached its maximum area in mid September at around 34 million square kilometres.  It was a little larger than the decadal mean in size, and was generally of average or above average stability.  PSCs began to form in mid May and the maximum area with potential PSCs was larger than the decadal mean and close to the maximum of the last decade at around 27 million square kilometres.  Ozone hole values below 220 DU were reached in late August, later than in the past couple of years; this was largely due to the stability in the stratosphere this year.  The ozone hole grew rapidly and by late September was above the average size for the decade at 23 million square kilometres.  Ozone values continue to drop across the continent.  Ozone depletion is expected to continue over the coming week.

The graphs above show the progress of the ozone hole for 2018. The gray shading indicates the highest and lowest values measured since 1979. The red numbers are the maximum or minimum values. The stratospheric temperature and the amount of sunlight reaching the south polar region control the depth and size of the Antarctic ozone hole. The dashed line in the minimum temperature plot indicates the temperature below which Type I (NAT) PSCs can form.   https://ozonewatch.gsfc.nasa.gov
 

Antarctic Situation at 2018 September 14British Antarctic Survey Ozone Bulletin

Antarctic ozone today:  Ozone values are dropping across the continent and the 2018 ozone hole has formed.  The hole is currently of average size for the decade at 20 million square kilometres.  The lowest ozone values, about 170 DU, are near McMurdo.  Amounts are higher, over 400 DU in places over the southern ocean, particularly south of Australia and New Zealand.  Ozone depletion is increasing, with values widely below the ozone hole threshold of 220 DU.  Ozone values over the continent range from around 170 DU to 260 DU.  There are marked differences between the various satellite ozone measurements and analyses across the Southern Hemisphere.  The KNMI analysis and TEMIS forecasts are close to the observed values, whereas the Canadian analysis seems largely based on SMOBA data and is clearly at variance with ground based observations.   The southern polar vortex is near its maximum size.  The atmospheric circulation is still in winter mode.   Temperatures in the ozone layer are just past their minimum and with the temperature widely below  -78°C Polar Stratospheric Clouds (PSC) are extensive in the central part of the ozone layer over the continent.  Ozone values are continuing to drop across the continent.  Temperatures are highest in a broad ring around 45°S and decline towards the pole, where they are coldest, and to the equator .  They are generally a little below the normal within the polar vortex.  The vortex area is a little larger than the decadal mean at around 34 million square kilometres near the centre of the ozone layer.  The area with PSCs present has passed its largest of around 27 million square kilometres, and has shrunk to around 20 million square kilometres, close to the decadal mean.  In general the lower stratosphere is of above average stability for the time of year and hence the vortex is roughly circular in shape.

The 2018 ozone hole:  The polar vortex began to form in early May and reached its maximum area in mid September at around 34 million square kilometres.  It was a little larger than the decadal mean in size, and was generally of average or above average stability.  PSCs began to form in mid May and the maximum area with potential PSCs was larger than the decadal mean and close to the maximum of the last decade at around 27 million square kilometres.  Ozone hole values below 220 DU were reached in late August, later than in the past couple of years; this was largely due to the stability in the stratosphere this year.  The ozone hole grew rapidly and by mid September was of average size for the decade at 20 million square kilometres.  Ozone values continue to drop across the continent.  Ozone depletion is expected to intensify over the coming week.

 

 
The graphs above show the progress of the ozone hole for 2018. The gray shading indicates the highest and lowest values measured since 1979. The red numbers are the maximum or minimum values. The stratospheric temperature and the amount of sunlight reaching the south polar region control the depth and size of the Antarctic ozone hole. The dashed line in the minimum temperature plot indicates the temperature below which Type I (NAT) PSCs can form.   https://ozonewatch.gsfc.nasa.gov

Antarctic Situation at 2018 September 3British Antarctic Survey Ozone Bulletin

Antarctic ozone today:  Ozone values are dropping across the continent and the 2018 ozone hole has formed.  The southern polar vortex is near its maximum size.  The atmospheric circulation is in winter mode with generally lower ozone over the continent and higher ozone over the Southern Ocean.   The lowest ozone values, below 200 DU, are near Halley.  Amounts are higher, over 400 DU in places over the southern ocean, particularly south of Australia.  Ozone depletion is increasing, with values below the ozone hole threshold of 220 DU.  Ozone values over the continent range from around 190 DU to 270 DU.  There are marked differences between the various satellite ozone measurements and analyses across the Southern Hemisphere.  The KNMI analysis is close to the observed values, whereas the Canadian analysis seems largely based on SMOBA data and is clearly at variance with ground based observations.   Temperatures in the ozone layer are nearing their minimum and with the temperature widely below  -78°C Polar Stratospheric Clouds (PSC) are extensive in the central part of the ozone layer over the continent.  Ozone values are continuing to drop over sunlit parts of the continent.  Temperatures are highest in a broad ring around 45°S and decline towards the pole, where they are coldest, and to the equator .  They are generally a little below the normal within the polar vortex.  The vortex area is close to the decadal mean at around 32 million square kilometres near the centre of the ozone layer.  The area with PSCs present is past its largest of around 27 million square kilometres, and has shrunk to around 24 million square kilometres, still a little larger than the decadal mean.  In general the lower stratosphere is a little above average stability for the time of year and hence the vortex is roughly circular in shape.

The 2018 ozone hole:  The polar vortex began to form in early May and reached its maximum area in mid August at around 32 million square kilometres.  It was a little larger than the decadal mean in size, and was generally of average or above average stability.  PSCs began to form in mid May and the maximum area with potential PSCs was larger than the decadal mean and close to the maximum of the last decade at around 27 million square kilometres.  Ozone hole values below 220 DU were reached in late August.  Ozone values are dropping over sunlit parts of the continent.  Ozone depletion is expected to intensify over the coming week.



Antarctic Situation at 2018 August 24British Antarctic Survey Ozone Bulletin

Antarctic ozone today:  Ozone values are dropping across the continent.  The southern polar vortex continues to grow, but is nearing its maximum size.  The atmospheric circulation is in winter mode with generally lower ozone over the continent and higher ozone over the Southern Ocean.   The lowest values, just below 220 DU, are on the northern fringes of the continent, but amounts are higher, near 450 DU in places, and building, over the southern ocean, particularly south of Australia and India.  Ozone depletion is increasing, with values at the ozone hole threshold of 220 DU.  Most short-term variation in ozone amount is due to dynamic processes.  Ozone values over the continent range from around 220 DU to 290 DU.  There are marked differences between the various satellite ozone measurements and analyses across the Southern Hemisphere.   Temperatures in the ozone layer are nearing their minimum and with the temperature widely below  -78°C Polar Stratospheric Clouds (PSC) have formed in the central part of the ozone layer over the continent.  Ozone values are dropping over sunlit parts of the continent, but have not quite reached ozone hole levels on a continuous basis.  Temperatures are highest in a broad ring around 45°S and decline towards the pole, where they are coldest, and to the equator .  They are generally a little below the normal within the polar vortex.  The vortex is growing in area, and is a little larger in size than the decadal mean at around 32 million square kilometres near the centre of the ozone layer.  The area with PSCs present is near its largest and is larger than the decadal mean and close to the maximum for the decade at around 27 million square kilometres.  In general the lower stratosphere is a little above average stability for the time of year and hence the vortex is roughly circular in shape.

The 2018 ozone hole:  The polar vortex is nearing its maximum area.  It is a little larger than the decadal mean in size, and generally of average stability.  The area with potential PSCs is larger than the decadal mean and close to the maximum of the last decade.  Ozone values are dropping over sunlit parts of the continent, and are near ozone hole levels.  Ozone depletion is expected to intensify over the coming week.

Provisional indications suggest that ozone hole levels were reached in the Arctic on 2018 February 3.  The region affected was between Svalbard and Scandinavia.  Very low ozone occurred over the west coast of Canada on February 12, 13, 16 and 17 in an event that was probably dynamically forced, although PSCs were seen.  A spring warming has occurred and all parts of the Arctic ozone layer are now above the PSC formation threshold.