Climate Prediction Center - Stratosphere: SBUV-2 Total Ozone - Ozone Hole (noaa.gov) 29 December 2020 WMO-The record-breaking 2020 Antarctic ozone hole finally closed at the end of December after an exceptional season due to naturally occurring meteorological conditions and the continued presence of ozone depleting substances in the atmosphereThe 2020 ozone hole grew rapidly from mid-August and peaked at around 24.8 million square kilometres on 20 September 2020, spreading over most of the Antarctic continent. It was the longest-lasting and one of the largest and deepest holes since the ozone layer monitoring began 40 years ago. It was driven by a strong, stable and cold polar vortex and very cold temperatures in the stratosphere (the layer of the atmosphere between around 10 km and round 50 km altitude).  “The last two ozone hole seasons demonstrate the year-to-year variability of the ozone hole and improve our understanding of the factors responsible for its formation, extent and severity,” said Oksana Tarasova, head of WMO Atmospheric Environment Research Division, which oversees WMO Global Atmosphere Watch network of monitoring stations. “We need continued international action to enforce the Montreal Protocol on ozone depleting chemicals. There is still enough ozone depleting substances in the atmosphere to cause ozone depletion on an annual basis,” said Dr Tarasova. WMO’s Global Atmosphere Watch programme works closely with Copernicus Atmospheric Monitoring Service, NASA, Environment and Climate Change Canada and other partners to monitor the Earth’s ozone layer, which protects us from the harmful ultraviolet rays of the sun. Strong Polar Vortex Ozone depletion is directly related to the temperature in the stratosphere, which is the layer of the atmosphere between around 10 km and round 50 km altitude. This is because polar stratospheric clouds, which have an important role in the chemical destruction of ozone, only form at temperatures below -78°C. These polar stratospheric clouds contain ice crystals that can turn non-reactive compounds into reactive ones, which can then rapidly destroy ozone as soon as light from the sun becomes available to start the chemical reactions. This dependency on polar stratospheric clouds and solar radiation is the main reason the ozone hole is only seen in late winter/early spring. During the Southern Hemisphere spring season (August - October) the ozone hole over the Antarctic increases in size, reaching a maximum between mid-September and mid-October (NASA Ozone Watch image of 2020 ozone hole at its September peak pictured left). When temperatures high up in the atmosphere (stratosphere) start to rise in late Southern Hemisphere spring, ozone depletion slows, the polar vortex weakens and finally breaks down, and by the end of December ozone levels have returned to normal. However, in 2020, a strong, stable and cold polar vortex kept the temperature of the ozone layer over Antarctica consistently cold, preventing the mixing of ozone depleted air above Antarctica with ozone rich air from higher latitudes.  For much of the 2020 season, stratospheric ozone concentrations around 20 to 25 km of altitude (50-100hPa) reached near-zero values with the ozone layer depth as low as 94 Dobson Units (a unit of measurement), or approximately one third of its normal value. The EU Copernicus Atmospheric Monitoring Service reported that ozone analyses showed the ozone hole had closed on 28 December. Every season, the appearance of the ozone hole and its evolution is monitored by means of satellites and a number of ground-based observing stations. Characteristics of the ozone hole,  interactive maps, timeseries, current state and forecast are being prepared and monitored by the large ozone community through the services of different organizations such as the Copernicus Atmosphere Monitoring Service (CAMS), NASA ozonewatch programme, NOAA,  KNMI,  ECCC and others.   Record-breaking 2020 ozone hole closes | World Meteorological Organization (wmo.int)

Depth of the 2020 ozone hole. The 2020 ozone hole is also one of the deepest. Measurements from the Copernicus Sentinel-5P satellite show that this year’s ozone hole has reached its maximum depth with a peak of around 100 DU on October 2. Credit: Contains modified Copernicus Sentinel data (2020), processed by DLR/BIRA/ESA Depth of the 2020 ozone hole. The 2020 ozone hole is also one of the deepest. Measurements from the Copernicus Sentinel-5P satellite show that this year’s ozone hole has reached its maximum depth with a peak of around 100 DU on October 2. Credit: Contains modified Copernicus Sentinel data (2020), processed by DLR/BIRA/ESA

https://ozonewatch.gsfc.nasa.gov

Antarctic Situation at 2020 November 30 British Antarctic Survey

Antarctic ozone today:  The 2020 ozone hole grew rapidly from mid August and peaked at around 25 million square kilometres (msqkm) in early October.  It is shrinking very slowly and still covers 17 msqkm, by far the largest for this time of year over the last decade and still covers much of the Antarctic continent.  Ozone amounts are generally high around the continent as the polar vortex blocks transport further south, and are past their minimum within the vortex.   Values range from around 150 DU within the vortex to around 360 DU outside it.  NASA Ozone Watch reports a lowest value of 94 DU recorded on October 6, the lowest for around 15 years.  The vortex area near the base of the ozone layer has passed its maximum size of around 33 msqkm in August, and has shrunk a little to 27 msqkm which is well above average for the time of year and close to its largest ever.  It remains very stable.  The temperature of the ozone layer over Antarctica has passed its minimum and is above the -78°C Polar Stratospheric Cloud (PSC) formation threshold in all parts of the ozone layer. The area with potential PSCs peaked at around 29 msqkm in July and had declined to around 0 msqkm by late November, reaching this point later in the year than for over a decade.  The temperature within the vortex is well below average values and is setting extreme minima for the period over the last forty years.  It is highest around Antarctica and declines towards the equator and over the Pole.  The ozone hole is expected to persist, although slowly filling, over the coming ten days, but is nearing its end. The Antarctic Peninsula will be mostly within the ozone hole over the next week, but the final remnant of the hole is likely to be expelled towards South Africa.  The margins of the ozone hole are likely to be over the tip of South America over the next few days, with the Falkland Islands and South Georgia also affected for most of the period.

Antarctic Situation at 2020 November 2 British Antarctic Survey

Antarctic ozone today:  The 2020 ozone hole grew rapidly from mid August and peaked at around 25 million square kilometres (msqkm) in early October.  It now covers 19 msqkm, above average for the last decade and covers most of the Antarctic continent.  Ozone amounts are generally high around the continent as the polar vortex blocks transport further south, and are past their minimum within the vortex.   Values range from around 130 DU within the vortex to nearly 400 DU outside it.  The broad area with lowest values is currently roughly near the Pole.  NASA Ozone Watch reports a lowest value of 94 DU recorded on October 6, the lowest for around 15 years.  The vortex area near the base of the ozone layer has passed its maximum size at around 33 msqkm, and has shrunk a little to 30 msqkm which is above average for the time of year.  It remains very stable.  The temperature of the ozone layer over Antarctica has passed its minimum but is below the -78°C Polar Stratospheric Cloud (PSC) formation threshold in the lower parts of the ozone layer. The area with potential PSCs peaked at around 29 msqkm in July and has declined to around 7 msqkm, the largest it has been at this time of year.  The temperature is below average values and is highest around Antarctica and declines towards the equator and over the Pole.  The ozone hole is expected to persist over the coming ten days, with the Antarctic Peninsula generally being outside the ozone hole.

November 2, 2020  NASA Ozone Watch
Persistent cold temperatures and strong circumpolar winds supported the formation of a large and deep Antarctic ozone hole in 2020, and it is likely to persist into November, NOAA and NASA scientists reported.
On September 20, 2020, the annual ozone hole reached its peak area at 24.8 million square kilometers (9.6 million square miles), roughly three times the size of the continental United States. Scientists also detected the near-complete elimination of ozone for several weeks in a 6-kilometer (4-mile) high column of the stratosphere near the geographic South Pole.

This year brought the 12th-largest ozone hole (by area) in 40 years of satellite records, with the 14th-lowest ozone readings in 33 years of balloon-borne instrumental measurements. However, scientists noted that ongoing declines in the atmospheric concentration of ozone-depleting chemicals (which are controlled by the Montreal Protocol) prevented the hole from being as large as it might have been under the same weather conditions 20 years ago.
“From the year 2000 peak, Antarctic stratosphere chlorine and bromine levels have fallen about 16 percent towards the natural level,” said Paul Newman, an ozone layer expert and the chief Earth scientist at NASA’s Goddard Space Flight Center. “We have a long way to go, but that improvement made a big difference this year. The hole would have been about a million square miles larger if there was still as much chlorine in the stratosphere as there was in 2000.”
This year represented a dramatic turnabout from 2019, when warm temperatures in the stratosphere and a weak polar vortex hampered the formation of polar stratospheric clouds (PSCs). The particles in PSCs activate forms of chlorine and bromine compounds that destroy ozone. Last year’s ozone hole was the smallest since the early 1980s, growing to 16.4 million square kilometers (6.3 million square miles) in early September.
“This clear contrast between last year and this year shows how meteorology affects the size of the ozone hole,” said Susan Strahan, a scientist with NASA Goddard and Universities Space Research Association. “It also complicates detection of long-term trends.”
Atmospheric levels of ozone-depleting substances increased up to the year 2000. Since then, they have slowly declined but remain high enough to produce significant seasonal ozone losses. During recent years with normal weather conditions, the ozone hole has typically grown to a maximum of 20 million square kilometers (8 million square miles).
In addition to the area of the ozone hole, scientists also track the average amount of ozone depletion—how little is left inside the hole. On October 1, 2020, weather balloons launched from NOAA’s South Pole atmospheric observatory recorded a low value of 104 Dobson units of atmospheric ozone. NASA’s Ozone Watch reported a lowest daily value at 94 Dobson Units on October 6. 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.
The amount of ozone between 13 to 21 kilometers (8 to 13 miles) in altitude, as measured over the South Pole, has been close to record lows at several points this year. “It’s about as close to zero as we can measure,” said Bryan Johnson, a scientist with NOAA’s Global Monitoring Laboratory. Still, the rate at which ozone declined in September was slower compared with 20 years ago, which is consistent with there being less chlorine in the atmosphere.
NASA Earth Observatory image by Joshua Stevens, using data courtesy of NASA Ozone Watch and GEOS-5 data from the Global Modeling and Assimilation Office at NASA GSFC. Story by Theo Stein, NOAA, and Ellen Gray, NASA Earth Science News Team, with EO Staff.

https://ozonewatch.gsfc.nasa.gov

Large, deep Antarctic ozone hole to persist into November

October 30, 2020 NOAA

Persistent cold temperatures and strong circumpolar winds supported the formation of a large and deep Antarctic ozone hole that will persist into November, NOAA and NASA scientists reported today. 

The ozone hole reached its peak size at about 9.6 million square miles (or 24.8 million square kilometers), roughly three times the area of the continental United States, on September 20. Observations revealed the nearly complete elimination of ozone in a four-mile-high column of the stratosphere over the South Pole.  

This year will go down as having the 12th-largest ozone hole in 40 years of satellite records, with the 14th-lowest ozone readings in 33 years of balloon-borne instrumental measurements, the scientists said. Declining levels of ozone-depleting chemicals controlled by the Montreal Protocol prevented the hole from being as large as it would have been 20 years ago.

"We have a long way to go, but that improvement made a big difference this year,” said Paul A. Newman, chief scientist for Earth Sciences at NASA's Goddard Space Flight Center. “The hole would have been about a million square miles larger if there was still as much chlorine in the stratosphere as there was in 2000.” 
What is ozone and why does it matter?
Ozone, composed of three oxygen atoms, is highly reactive with other chemicals. In the stratosphere, roughly 7 to 25 miles above Earth’s surface, the ozone layer acts like sunscreen, shielding the planet from ultraviolet radiation. Closer to Earth’s surface, ozone created by  photochemical reactions between the sun and pollution from vehicle emissions and other sources can form harmful smog in the lower atmosphere.
This year represented a dramatic turnabout from 2019, when warm temperatures in the stratosphere and a weak polar vortex limited ozone hole growth to 6.3 million square miles (16. 4 million square kilometers), the smallest on record. 
How do NOAA and NASA measure ozone?
NASA and NOAA monitor the ozone hole by using three complementary instrumental methods. 
Satellites, including NASA’s Aura satellite and NASA-NOAA Suomi National Polar-orbiting Partnership satellite, measure the size of the ozone hole from space. The Aura satellite’s Microwave Limb Sounder estimates levels of ozone-destroying chlorine. 
NOAA staff at the South Pole also launch weather balloons carrying ozone-measuring sondes that directly sample ozone levels vertically through the atmosphere. Once sunshine returns after the long polar night, with a ground-based instrument called a Dobson spectrophotometer. 
Bryan Johnson, a scientist with NOAA’s Global Monitoring Lab, said ozonesonde measurements recorded a low daily value of 104 Dobson units on October 1. In late October, ozone levels between 8 and 13 miles in altitude were still “about as close to zero as we can measure.” A Dobson unit is the standard measurement for the total amount of ozone in the atmosphere above a point on Earth's surface.  
The amount of ozone in the atmosphere is exceedingly small. Prior to the emergence of the 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. If 300 Dobson units of ozone were compressed into a layer of pure ozone, it would approximate the thickness of two pennies stacked one on top of the other. 

Antarctic Situation at 2020 October 21 British Antarctic Survey

Antarctic ozone today:  The 2020 ozone hole grew rapidly from mid August and peaked at around 25 million square kilometres (msqkm) in early October.  It now covers 22 msqkm, above average for the last decade and covers most of the Antarctic continent.  Ozone amounts are generally high around the continent as the polar vortex blocks transport further south, and are past their minimum within the vortex.   Values range from around 110 DU within the vortex to over 400 DU outside it.  The area with lowest values is currently a little offset from the Pole towards South Africa.  NASA Ozone Watch reports a lowest value of 94 DU recorded on October 6, the lowest for around 15 years.  The vortex area near the base of the ozone layer has passed its maximum size at around 33 msqkm, and has shrunk a little to 31 msqkm which is above average for the time of year.  It remains very stable.  The temperature of the ozone layer over Antarctica has passed its minimum but is below the -78°C Polar Stratospheric Cloud (PSC) formation threshold in the lower parts of the ozone layer. The area with potential PSCs peaked at around 29 msqkm in July and has declined to around 13 msqkm, the largest it has been at this time of year.  The temperature is mostly a little below average values and is highest around Antarctica and declines towards the equator and over the Pole.  Severe ozone depletion is expected to persist over the coming week with the northern part of the Antarctic Peninsula largely outside the ozone hole until near the end of the month.

Antarctic Situation at 2020 October 12 British Antarctic Survey

Antarctic ozone today:  The 2020 ozone hole grew rapidly from mid August and peaked at around 24 million square kilometres (msqkm) in early October.  It now covers 22 msqkm, above average for the last decade and covers most of the Antarctic continent.  Ozone amounts are generally high around the continent as the polar vortex blocks transport further south, and are just past their minimum within the vortex.   Values range from around 110 DU within the vortex to well over 400 DU outside it.  The area with lowest values is currently roughly over Dronning Maud Land.  NASA Ozone Watch reports a lowest value of 94 DU recorded on October 6, the lowest for around 15 years.  The vortex area near the base of the ozone layer has passed its maximum size at around 33 msqkm, and has shrunk a little to 31 msqkm which is near average for the time of year.  It remains very stable.  The temperature of the ozone layer over Antarctica has passed its minimum but is below the -78°C Polar Stratospheric Cloud (PSC) formation threshold in the lower parts of the ozone layer. The area with potential PSCs peaked at around 29 msqkm in July and has declined to around 13 msqkm, well above the average for the time of year.  The temperature is mostly a little below average values and is highest around Antarctica and declines towards the equator and over the Pole.  Severe ozone depletion is expected to persist over the coming week with the hole transiting back from being elliptical to circular.

https://ozonewatch.gsfc.nasa.gov

2020 Antarctic ozone hole is large and deep

Published

The annually occurring ozone hole over the Antarctic is one of the largest and deepest in recent years. Analyses show that the hole has reached its maximum size.

The 2020 ozone hole grew rapidly from mid-August and peaked at around 24 million square kilometres in early October.  It now covers 23 million km2, above average for the last decade and spreading over most of the Antarctic continent. 

WMO’s Global Atmosphere Watch programme works closely with Copernicus Atmospheric Monitoring Service, NASA, Environment and Climate Change Canada and other partners to monitor the Earth’s ozone layer, which protects us from the harmful ultraviolet rays of the sun.

NASA’s Ozone Watch reports a lowest value of 95 Dobson Units recorded on October 1.  Scientists are seeing signs that the 2020 ozone hole now seems to have reached its maximum extent.

“There is much variability in how far ozone hole events develop each year. The 2020 ozone hole resembles the one from 2018, which also was a quite large hole, and is definitely in the upper part of the pack of the last fifteen years or so”, Vincent-Henri Peuch, Director of Copernicus Atmosphere Monitoring Service at ECMWF, said in a news release.

“With the sunlight returning to the South Pole in the last weeks, we saw continued ozone depletion over the area. After the unusually small and short-lived ozone hole in 2019, which was driven by special meteorological conditions, we are registering a rather large one again this year, which confirms that we need to continue enforcing the Montreal Protocol banning emissions of ozone depleting chemicals.”

The Montreal Protocol bans emissions of ozone depleting chemicals. Since the ban on halocarbons, the ozone layer has slowly been recovering; the data clearly show a trend in decreasing area of the ozone hole.

The latest WMO /UN Environment Programme Scientific Assessment of Ozone Depletion, issued in 2018, concluded that the ozone layer on the path of recovery and to potential return of the ozone values over Antarctica to pre-1980 levels by 2060.

The large ozone hole in 2020 has beendriven by a strong, stable and cold polar vortex, which kept the temperature of the ozone layer over Antarctica consistently cold.

Ozone depletion is directly related to the temperature in the stratosphere, which is the layer of the atmosphere between around 10 km and round 50 km altitude. This is because polar stratospheric clouds, which have an important role in the chemical destruction of ozone, only form at temperatures below -78°C.

These polar stratospheric clouds contain ice crystals that can turn non-reactive compounds into reactive ones, which can then rapidly destroy ozone as soon as light from the sun becomes available to start the chemical reactions. This dependency on polar stratospheric clouds and solar radiation is the main reason the ozone hole is only seen in late winter/early spring.

Stratospheric ozone concentrations have been observed to have reduced to near-zero values over Antarctica around 20 to 25 km of altitude (50-100hPa), with the ozone layer depth coming just below 100 Dobson Units, about a third of its typical value outside of ozone hole events. 

During the Southern Hemisphere spring season (August - October) the ozone hole over the Antarctic increases in size, reaching a maximum between mid-September and mid-October. When temperatures high up in the atmosphere (stratosphere) start to rise in late Southern Hemisphere spring, ozone depletion slows, the polar vortex weakens and finally breaks down, and by the end of December ozone levels have returned to normal.

https://public.wmo.int/en/media/news/2020-antarctic-ozone-hole-large-and-deep

Antarctic Situation at 2020 October 5  British Antarctic Survey

Antarctic ozone today:  The 2020 ozone hole grew rapidly from mid August and peaked at around 24 million square kilometres (msqkm) in early October.  It now covers 23 msqkm, above average for the last decade and covers most of the Antarctic continent.  Ozone amounts are generally high around the continent as the polar vortex blocks transport further south, and are near their minimum within the vortex.   Values range from around 100 DU within the vortex to well over 400 DU outside it.  The area with lowest values is roughly over the polar plateau at the longitude of South Africa.  NASA Ozone Watch reports a lowest value of 95 DU recorded on October 1.  The vortex area near the base of the ozone layer has passed its maximum size at around 33 msqkm, and has shrunk a little to 32 msqkm which is near average for the time of year.  It remains very stable.  The temperature of the ozone layer over Antarctica has passed its minimum but is below the -78°C Polar Stratospheric Cloud (PSC) formation threshold in most parts. The area with potential PSCs peaked at around 29 msqkm in July and has declined to around 17 msqkm, still above the average for the time of year.  The temperature is mostly close to or a little below average values and is highest around Antarctica and declines towards the equator and over the Pole.  Severe ozone depletion is expected to persist over the coming week with the hole transiting from circular to elliptical.

Antarctic Situation at 2020 September 15 British Antarctic Survey

Antarctic ozone today:  The 2020 ozone hole has grown rapidly and now covers 22 million square kilometres (msqkm), well above average for the last decade.  It covers most of the Antarctic continent.   Ozone amounts are generally high around the continent as the polar vortex blocks transport further south, and are decreasing within the vortex.   Values range from around 150 DU within the vortex to well over 400 DU outside it.  Lowest values are in a horse-shoe shaped arc.  The vortex area near the base of the ozone layer has passed its maximum size at around 33 msqkm, and has shrunk a little to 32 msqkm which is near average for the time of year.  The temperature of the ozone layer over Antarctica is near its minimum and is below the -78°C Polar Stratospheric Cloud (PSC) formation threshold in most parts. The area with potential PSCs peaked at around 29 msqkm in July and has declined to around 21 msqkm, still a little above the average for the time of year.  The temperature is mostly close to or a little below average values and is highest around Antarctica and declines towards the equator and over the Pole.  Ozone depletion is expected to continue over the coming ten days.

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

Antarctic Situation at 2020 September 7 British Antarctic Survey

Antarctic Situation at 2020 August 24 British Antarctic Survey

Antarctic ozone today:  The 2020 ozone hole is growing.   Ozone amounts are generally building around the continent as the polar vortex blocks transport further south, and are decreasing within the vortex.   Values range from around 190 DU within the vortex to over 400 DU outside it.  Lowest values are over West Antarctica.  Rothera experienced its first ozone hole day on June 30.  The vortex area is still slowly increasing and covers around 33 million square kilometres (msqkm) near the base of the ozone layer, which is above average for the time of year.  The temperature of the ozone layer over Antarctica is near its minimum and is below the -78°C Polar Stratospheric Cloud (PSC) formation threshold in most parts, giving an area with potential PSC of 25 msqkm, above the average for the time of year.  The temperature is mostly close to or a little below average values and is highest around Antarctica and declines towards the equator and over the Pole.  Ozone depletion is expected to increase over the coming ten days as photochemistry and planetary wave forcings play their part.

Antarctic Situation at 2020 August 17 British Antarctic Survey

Antarctic ozone today:  The 2020 ozone hole is growing.   Ozone amounts are generally building around the continent as the polar vortex blocks transport further south, and are decreasing within the vortex.   Values range from around 220 DU within the vortex to over 400 DU outside it.  Lowest values are near the Pole towards the Antarctic Peninsula.  Rothera experienced its first ozone hole day on June 30.  The vortex area is increasing and now covers around 33 million square kilometres (msqkm) near the base of the ozone layer, which is above average for the time of year.  The temperature of the ozone layer over Antarctica is falling and is now below the -78°C Polar Stratospheric Cloud (PSC) formation threshold in most parts, giving an area with potential PSC of 27 msqkm, above the average for the time of year.  The temperature is mostly close to or a little below average values and is highest around Antarctica and declines towards the equator and over the Pole.  Ozone depletion is expected to increase over the coming ten days as photochemistry and planetary wave forcings play their part.

Antarctic Situation at 2020 August 10 British Antarctic Survey

Antarctic ozone today:  The 2020 ozone hole is growing.   Ozone amounts are generally building around the continent as the polar vortex blocks transport further south, and are decreasing within the vortex.   Values range from around 190 DU within the vortex to around 390 DU outside it.  Lowest values are over the Southern Ocean in the Pacfic sector.  Rothera experienced its first ozone hole day on June 30.  The vortex area is increasing and now covers around 32 million square kilometres (msqkm) near the base of the ozone layer, which is above average for the time of year.  The temperature of the ozone layer over Antarctica is falling and is now below the -78°C Polar Stratospheric Cloud (PSC) formation threshold in most parts, giving an area with potential PSC of 27 msqkm, above the average for the time of year.  The temperature is mostly close to or a little below average values and is highest around Antarctica and declines towards the equator and over the Pole.  Ozone depletion is expected to increase over the coming ten days as photochemistry and planetary wave forcings play their part.