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ANTARCTIC OZONE
This page gives information about ozone at Halley, Rothera and Vernadsky/Faraday
stations. It was either updated or new data was added on 2019
October 4.
The next update will be in early
October.
Antarctic ozone today: An annual stratospheric warming commenced unusually early this year and temperatures are rising through much of the ozone layer. The area above Antarctica with Polar Stratospheric Clouds (PSCs) has dropped to near zero, the smallest at this time of year for decades. The polar vortex has begun to shrink and is now 23 million square kilometres in area near the base of the ozone layer; this is smaller than it has been in the last decade. It is shrinking more rapidly higher in the ozone layer. The vortex is offset from the Pole towards the Atlantic. Lowest ozone amounts, around 190 DU, are over Dronning Maud Land. Ozone amounts are much higher around Antarctica over the southern ocean with amounts near 450 DU in places. The ozone hole is currently some 7 million square kilometres in area, down from a peak of around 11 million square kilometres in area in early September and smaller than ever seen in the last decade. Overall the stratosphere has been much less stable than usual, which is giving rise to the small size of the vortex. More stable conditions have returned and the ozone hole is expected to remain stable over the coming 10 days, remaining offset from the pole towards the Atlantic.
The 2019 ozone hole: The 2019 polar vortex began to form in May and had reached some 20 million square kilometres in area near the base of the ozone layer by early July; this was smaller than over the last decade. At the time of the solstice, the growing polar vortex was unusually offset towards the Indian Ocean and centred over East Antarctica. It returned to being more pole centred and by early August was some 28 million square kilometres in area. Since the solstice it has been near the smallest over the last decade and has generally been offset towards the Atlantic. It reached its maximum size in late August, unusually early. Temperatures in the ozone layer were below the -78°C Polar Stratospheric Cloud (PSC) formation threshold from late May until the equinox. The spring warming of the stratosphere began in early September. Such an early pulse of warming in the stratosphere was not uncommon in the years prior to the formation of an ozone hole in the 1980s, but it has been rarer in the last 30 years. The area with potential PSCs reached a peak of some 26 million square kilometres in area at times from mid July to August and then declined rapidly. Satellite observations show that the ozone hole began to grow from mid-August and reached a peak of around 11 million square kilometres in area in early September. It then shrank to 3 million square kilometres as a result of the warming, but has since grown and is currently some 7 million square kilometres in area, still smaller than seen over the last decade. Overall the stratosphere has been quite disturbed during the winter, with strong wave activity with a period of around a month, and this gave rise to the smaller than usual vortex.
See the final situation report for last year for information on the 2018 - 2019 season.
Notes: An ozone hole is defined as an area with values below 220 Dobson Units (DU). On average a column of air will hold 300 DU of ozone, equivalent to 3mm of ozone at sea-level pressure. Most of the ozone is between 10 and 40 km with a peak at around 20 km. The Antarctic ozone hole is usually largest in early September and deepest in late September to early October. September 16 is world ozone day, and in 2009 the final UN Member State to ratify the Montreal Protocol signed up. All 197 Member States have now ratified the protocol up to and including the Beijing amendments. 2007 was the International Year of the Ozone Layer. Prior to the formation of ozone holes, Antarctic ozone values were normally at their lowest in the autumn (ie March). On occasion atmospheric vertical motions create small areas with ozone substantially below the long term average. Different satellites give different views of the exact ozone distribution. The continent covers 14 million sq. km. A summary of the WMO/UN 2014 Ozone Assessment, the Assessment for Decision-Makers was released on 2014 September 10. 2017 was the 30th Anniversary of the Montreal Protocol. The US Government shutdown in 2019 means that some NOAA/NASA data about the stratosphere is not currently available. 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.
News: Observations reported in Nature in May 2018 showed that the rate of decline of CFC-11, an ozone depleting substances in the atmosphere, which is also a greenhouse gas, had become slower than predicted. This suggested that either something unusual was taking place in the atmosphere or that there were additional man-made emissions. The paper suggested that the most likely reason was illegal manufacture and release from somewhere in eastern Asia. Investigation by the EIA has found that production of polyurethene foam in China can explain the observed changes. They encourage the Chinese government to take immediate action. This became news again in May 2019 when another paper was published in Nature.
Observations
from Halley since 1994 (the year when ozone depleting gasses were at their peak
according to one estimate) show a slow increase of about 1 DU per year in the
minimum ozone amount recorded each October, however the inter-annual variation
is such that this trend is not yet significant (at the 99% level), ie the data
is also consistent with no change in the minimum amount. Although the
amount of ozone destroying substances in the atmosphere is going down, the
inter-annual variation in the size and depth of the ozone hole is largely
controlled by the meteorological conditions in the stratosphere. The
provisional Halley 2015 October minimum value was lower than that of 2014, 2013
and 2012 and this was due to the prevailing meteorological conditions. It
was also influenced by the eruption from Calbuco in southern Chile. The
recovery in springtime (ie September and October) minimum ozone values at Halley
is now statistically significant. A simple extrapolation of the trend in
minimum values gives the final year with ozone hole levels as 2073, though the
error bars on this estimate are very large. Models suggest that recovery
may be more rapid after 2010. It is still too soon to say that we have
had the worst ever ozone hole, particularly as there has been no major volcanic
eruption in the Southern Hemisphere since 1992. There has also been little
cooling of the lower stratosphere since the mid 1990s.
Click on a thumbnail to get the latest graph or high resolution images, which are updated more frequently than the thumbnails.
Halley - Total ozone:
The Dobson ozone observing season at Halley normally begins at the end of August and
ends in mid April. Very early and late season observations are made
with the Sun at low elevation, and are less accurate than those made during the
main observing period of September 6 to April 6. In addition the Dobson at
Halley was changed in 2012 February and required maintenance in 2013 August, so
the zenith sky tables of the current instrument are not yet fully determined.
Ozone observations at the station ceased
on 2017 February 15 when the station was shut down for the winter due to the risk of
calving of the ice shelf on which it
is located.
Manual observations resumed
on 2017 December 7, but ceased for the winter on 2018 February 26.
Jonathan Shanklin was on station over the summer and made many calibration
observations. An automated Dobson ran for a short while during 2018 January and
February, and resumed in 2019 January. The preliminary automated Dobson values given here should be treated with some caution
and will be revised as there is good evidence that the currently calculated
values are too high when ozone values are low.
Automated observations resumed in late August, and they suggest that ozone levels have fallen from around 270 DU (10% depletion) to 245 DU (15% depletion) however comparison with other sources suggests that these values may be too high. The lowest value recorded to date this season is 238 DU on September 28. Very unusually the data suggest that Halley has not been within the ozone hole so far this season.
Rothera - Total ozone:
Real-time graphs showing current ozone and NO2 levels. There are occasional periods when the
computed values appear erroneous and this is 
likely due to internal clock
errors. Ozone values were around 280 DU in the first half of January.
The instrument then stopped working for a lengthy period, but following a return
to measurements, values were around 290 DU for most of the first half of the
year, with wave activity giving some longer period fluctuation of around +/- 20
DU. Stronger wave activity pushed values to a peak of around 320 DU at the
solstice, but they fell to a minimum of around 230 DU in mid July before rising
again to around 295 DU in late July, a little above the normal. By the
third week of August they had dropped to around 145 DU, but have risen and are
now around 280 DU, well above the average for the date. The station
experienced its first "ozone hole" day of the season on July 2 and was within
the growing ozone hole from August 11 to September 20. The lowest value
recorded this season was 110 DU on August 19 and the highest to date is 351 DU on
October 3. The September mean is the highest since 1985. Superimposed on the general trends described
here are fluctuations with periods of days to around a month and values can
change by over 50% in a few days in the spring when the polar vortex rotates
across the station.
Vernadsky - Total ozone: Vernadsky station is run by the
National Antarctic Scientific Centre of Ukraine. It is some 250 km north of
Rothera. The observing season at Vernadsky began in late July, when ozone
values were around 230 DU, though they quickly recovered to around 300 DU by the
end of the month. They fell rapidly to around 180 DU (45% depletion)
during the first three weeks of August. Mean values rose slowly to 190 DU
(40% depletion) in mid September and then rapidly to just below normal values
around 315 DU late in the month. Mean values are currently around 290 DU
(15% depletion). The lowest value recorded
this season was 144 DU on September 3 and the highest to date is 403 DU on
September 26.
Superimposed on the general trends during the year are fluctuations with periods of days to around a month and values can change by over 50% in a few days in the spring when the polar vortex rotates across the station, which is usually near the edge region of the polar vortex. Very early and late season observations are made with the Sun at low elevation, and are less accurate than those made during the main observing period of August 6 to May 6. The instrument constants were revised in 2016 November, which resulted in some previously listed values for 2016 and earlier being updated. A further revision may be required. See the data section for current provisional values for 1972 - date.
Temperature
and PSCs: The 100 hPa pressure level is near the base of the ozone
layer, but is reached by most radiosonde flights. The
temperature at this height is sufficiently cold from July to October that polar
stratospheric clouds (PSCs) can form. Note: "the normal" is used to refer to
the long term mean for the time of year.
Both Halley and Rothera see
displays of nacreous clouds. Those at Halley are of the form described
during the IGY as "ultra-cirrus". The 2019 season started early
at Rothera with a sighting on May 22. They also saw nacreous clouds on
June 3, 12, 13, 17, July 1, 2, 3, 4, August 9, 10, 13, 14, 16, 18, 20.
Halley - 100 hPa temperature: The station is currently
unoccupied and no sonde flights are taking place.
Peninsula - 100 hPa temperature:
The 100 hPa temperature started the year at around -45°C,
a little cooler than the 30-year mean. It generally fell and had reached -70°C in early June.
Then the offset
of the polar vortex towards the Indian Ocean pushed temperatures back up to -60°C
around the time of the solstice, which is
much above the historic
mean
for the time of year. It fell to around -82°C in early September, which is
7° below
the historic mean for the time of year. It is now rising and is around
-61°C, 10° above the historic mean for the time of year. There is often large day to day variation during the spring because the area is
in the edge region of the circumpolar vortex.
The June mean temperature was the joint warmest since 2013.
All the colder winters in the ozone layer have been within the last 15 years.
Arctic: Ozone values across the Arctic and temperate parts of the Northern Hemisphere are nearing the autumn minimum and generally lower over the pole than mid temperate latitudes. They range from around 240 DU to around 360 DU. Ozone amounts over the UK are around 280 DU. The ozone layer temperature is well above the PSC formation temperature, but is falling.
The north polar vortex is usually smaller and more disturbed than the corresponding one that forms during the Antarctic winter. It was relatively large and stable during the winter of 2017/18. Significant ozone depletion affected the north polar region during January and February 2018. Values were low between Svalbard and Scandinavia, where ozone hole levels below 220 DU appear to have been reached on 2018 February 3. Low values below 220 DU were also reached near the west coast of Canada on 2018 February 12, 13, 16 and 17, in what appears to be dynamic event, although PSCs were seen. A major spring warming then took place with a rapid rise in ozone amounts across the northern polar regions.
There are sometimes significant differences (over 100 DU) between modeled, satellite and ground-based measurements, particularly when there is large variation in total column ozone. Ozone values over the Arctic during 2018/19 are shown in our Northern Hemisphere OMI movie. For more UK information see the DEFRA UK Stratospheric Ozone Measurements page.
Equator: Ozone levels are normally lowest over the topics and OMI data shows nothing unusual. The latest theories on how the ozone layer will change in response to increased carbon dioxide in the atmosphere suggest that there will be a slow decline in ozone amounts over tropical and sub-tropical regions.
Measurements reported here refer to ozone in the "ozone layer", where most of the ozone in the atmosphere is found. This "layer" stretches from roughly 10 to 40km above the Earth's surface, with a peak at around 20km. Bringing all the ozone in the "layer" down to ground level would give a thickness of around 3mm of pure ozone, which reduces to around 1mm at the height of the ozone hole. A little ozone also exists closer to the Earth's surface and research shows that natural halogens in Antarctica can produce depletion in this near surface layer. The theoretical basis for the formation of the Antarctic ozone hole and its link with the halogen chemistry of man-made substances is well established and the mechanism is described at sites such as the Ozone Hole Tour at the Cambridge University Centre for Atmospheric Science.
The BAS ozone bulletins contained the actual ozone values reported together with an analysis of the situation. These were distributed by email on request, but are now superceded by this web site. The last email ozone bulletin was issued on 2002 May 28. The final situation report of each season is archived for historical reference.
Please read this metadata
description before asking any questions about the data.
[updated 2018 February 26].
Two documents describe our standard operating procedures:
The BAS Dobson Manual
and the BAS ozone station
instructions. A paper describing the stations, observing programs and
reduction procedures is in preparation. Most of our data is available on line,
however please note that this is provisional and likely to change without
warning. You must request permission to reproduce the data and we may be
able to supply more suitable or more up to date material. If data from
Halley is used you must give the station name as Halley; Halley Bay was a
geographical feature that no longer exists.
Older data (1972 - 2011) has been recomputed and all the preliminary values are posted. Some of the zenith sky regressions do not give a good fit and will be improved. The direct sun measurements during this period are unlikely to change.
Current provisional daily
mean ozone values for 2019/2020 for Halley
[Updated 2019 October 4] and Vernadsky. [Updated 2019 October 4].
Note : The Dobson at Halley was changed in 2012 February and
required maintenance in 2013 August. The calibration of the current
instrument is not yet fully determined. The zenith sky tables or other
calibration values were last revised on 2018 February 4, but the daily means may
still have errors up to 5%, particularly when ozone values or the solar
elevation are low. The instrument constants for Dobson 123 at Vernadsky
were revised in 2017 December and may require further revision. The preliminary
Halley and Vernadsky values should therefore be treated with some caution.
Halley has become a summer only station and there are no manual observations
between 2017 February 15 and 2017 December 7,
2018 February 26 and 2018 December 10 and since 2019 February 16. The instrument calibration constants
are being
revised, so values given here may change.
Halley
Provisional daily mean ozone values for Halley in
2011/12 , 2012/13
,
2013/14 , 2014/15
,
2015/16 , 2016/17
, 2017/18 , 2018/19 using Dobson 31.
Provisional daily mean ozone values for Halley in
2005/06 , 2006/07
,
2007/08 , 2008/09
,
2009/10 , 2010/11
,
2011/12 using Dobson 73 in manual mode. 2017/18
, 2018/19 , 2019/20 using Dobson 73 in auto mode.
Provisional daily mean ozone values for Halley in
1991/92 , 1992/93
,
1993/94 , 1994/95
,
1995/96 , 1996/97
,
1997/98 , 1998/99
,
1999/00 , 2000/01
,
2001/02 , 2002/03
,
2003/04 , 2004/05
,
2005/06
using Dobson 103.
Provisional daily mean ozone values for Halley in
1981/82 , 1982/83
,
1983/84 , 1984/85
,
1985/86 , 1986/87
,
1987/88 , 1988/89
,
1989/90 , 1990/91
,
1991/92
using Dobson 123.
Provisional daily mean ozone values for Halley in
1972/73 ,
1973/74 , 1974/75
,
1975/76 , 1976/77
,
1977/78 , 1978/79
,
1979/80 , 1980/81
,
1981/82
using Dobson 31.
Provisional individual ozone values for Halley
in
2011/12 , 2012/13
,
2013/14 , 2014/15
, 2015/16 ,
2016/17 , 2017/18 ,
2018/19 using Dobson 31.
Provisional individual ozone values for Halley in
2005/06 , 2006/07
,
2007/08 , 2008/09
,
2009/10 , 2010/11
,
2011/12 with Dobson 73 in manual mode, 2017/18
, 2018/19 , 2019/20 using Dobson 73 in auto mode.
Provisional individual ozone values for Halley in
1991/92 , 1992/93
,
1993/94 , 1994/95
,
1995/96 , 1996/97
,
1997/98 , 1998/99
,
1999/00 , 2000/01
,
2001/02 , 2002/03
,
2003/04 , 2004/05
,
2005/06
using Dobson 103.
Provisional individual ozone values for Halley in
1981/82 , 1982/83
,
1983/84 , 1984/85
,
1985/86 , 1986/87
,
1987/88 , 1988/89
,
1989/90 , 1990/91
,
1991/92
using Dobson 123.
Provisional individual ozone values for Halley in
1972/73 ,
1973/74 , 1974/75
,
1975/76 , 1976/77
,
1977/78 , 1978/79
,
1979/80 , 1980/81
,
1981/82
using Dobson 31.
Faraday/Vernadsky
Provisional daily mean
ozone values for Vernadsky in
2004/05 , 2005/06
, 2006/07 ,
2007/08 , 2008/09
, 2009/10 ,
2010/11 , 2011/12
, 2012/13 ,
2013/14 , 2014/15
, 2015/16 ,
2016/17 , 2017/18 ,
2018/19 , 2019/20 using Dobson 123.
Provisional daily mean ozone values for Vernadsky in
1983/84 , 1984/85
, 1985/86 ,
1986/87 , 1987/88
, 1988/89 ,
1989/90 , 1990/91
, 1991/92 ,
1992/93 , 1993/94
, 1994/95 ,
1995/96 , 1996/97
, 1997/98 ,
1998/99 , 1999/00
, 2000/01 ,
2001/02 , 2002/03
, 2003/04 ,
2004/05 using Dobson 31.
Provisional daily mean ozone values for Vernadsky in
1971/72 ,
1972/73 , 1973/74
, 1974/75 ,
1975/76 , 1976/77
, 1977/78 ,
1978/79 , 1979/80
, 1980/81 ,
1981/82 , 1982/83
, 1983/84 ,
1984/85 using Dobson 73.
Provisional individual ozone values for Vernadsky in
2004/05 , 2005/06
, 2006/07 ,
2007/08 , 2008/09
, 2009/10 ,
2010/11 , 2011/12
, 2012/13 ,
2013/14 , 2014/15
, 2015/16 ,
2016/17 , 2017/18 ,
2018/19 , 2019/20 using Dobson 123.
Provisional individual ozone values for Vernadsky in
1983/84 , 1984/85
, 1985/86 ,
1986/87 , 1987/88
, 1988/89 ,
1989/90 , 1990/91
, 1991/92 ,
1992/93 , 1993/94
, 1994/95 ,
1995/96 , 1996/97
, 1997/98 ,
1998/99 , 1999/00
, 2000/01 ,
2001/02 , 2002/03
, 2003/04 ,
2004/05 using Dobson 31.
Provisional individual ozone values for Vernadsky in
1971/72 ,
1972/73 , 1973/74
, 1974/75 ,
1975/76 , 1976/77
, 1977/78 ,
1978/79 , 1979/80
, 1980/81 ,
1981/82 , 1982/83
, 1983/84 ,
1984/85 using Dobson 73.
Provisional monthly mean ozone values for Faraday/Vernadsky and Halley between 1956 and 2019 September.
Provisional monthly minimum ozone values for Faraday/Vernadsky between 1972 and 2018 April and Halley between 1956 and 2019 September.
Mean daily ozone values for the period 1957 - 1972 for
Faraday
and Halley. [NB: not corrected to Bass-Paur]
Daily ozone values for the period 1957 - 1973 for Faraday and Halley. [Revised to Bass-Paur]
Provisional Halley SAOZ total column nitrogen dioxide
and ozone:
2013 [processing revised 2013 November 22] ,
2014 ,
2015 , 2016 [updated
2016 December 12] and as
real-time graphs showing current ozone and NO2 levels [Not yet available].
The SAOZ did not run during the 2018 winter; it may run during the 2019 winter.
Temperature and Ozone graphs for Halley and Vernadsky/Faraday. [Updated 2017 July 24]. The historic period shown in the inline graphs is for 1957 - 1972.
Rothera
Ozone & nitrogen dioxide:
SAOZ total column nitrogen dioxide and ozone:
1996 ,
1997 , 1998 ,
1999 ,
2000 , 2001 ,
2002 ,
2003 , 2004 ,
2005 ,
2006 , 2007 and
2008
[to 2008 January 22].
"New" SAOZ total column nitrogen dioxide and ozone:
2006 , 2007 ,
2008 ,
2009 , 2010 ,
2011 ,
2012 , 2013 ,
2014 ,
2015 , 2016 ,
2017 , 2018 , 2019
[updated 2019 October 4]
and as
real-time graphs showing current ozone and NO2 levels. Data is missing
between 2013 December 23 and 2014 January 6. Data from 2017 January 6 to
May 8 is
likely to be revised as there were some issues with the instrument. Some
data in 2017 October and November, which show high standard deviation is also
suspect, though in some cases this simply reflects large changes in ozone column
during the day. There are some shorter periods with missing data due to
computer glitches. These became more problematic in 2019 and no data was collected
between 2019 January 18 and March 4.
Provisional monthly mean ozone values
from 1996 to 2019 September.
Note that means for some months are based on partial data.
Ozonesondes:
During 2003 we carried out ozone sonde flights at Rothera as part of the
QUOBI project. Data from these
flights
is available in NASA-AMES format. Animation
of the ozonesonde flight results [note that although the ozone scale on these
graphs reads nanobars, it should read mPa].
Bentham ozone. Provisional values for 1997
/ 1998 / 1999 /
2000
/ 2001 / 2003 /
2004 [updated 2004 November 5]. The
Bentham instrument ran until 2012, but data from it has not been used to produce
further ozone values.
Some background information on Halley, Rothera and Faraday stations is available from BAS. Information about Vernadsky station is also available from the Ukrainian Antarctic Centre. Information about Vladimir Ivanovich Vernadsky
Some surface and upper air synoptic data is also available on line from our public data page.
Southern Hemisphere ozone
hole movies for 1997/1998 , 1998/1999
, 1999/2000 , 2000/2001
, 2001/2002 , 2002/2003
, 2003/2004 , 2004/2005
, 2005 [TOMS], 2005/2006
, 2006/2007 , 2007/2008
, 2008/2009 , 2009/2010
, 2010/2011 , 2011/2012
, 2012/2013 , 2013/2014
, 2014/2015 , 2015/2016
, 2016/2017 , 2017/2018
, 2018/2019 , 2019/2020
[OMI, updated 2019 September 16]. A short sequence of the
2001 ozone hole.
Northern Hemisphere movies for 2000/2001 , 2001/2002
, 2002/2003 ,
2003/2004
, 2004/2005 , 2005
[TOMS], 2005/2006 ,
2006/2007
, 2007/2008 , 2008/2009
, 2009/2010 , 2010/2011
, 2011/2012 , 2012/2013
, 2013/2014 , 2014/2015
, 2015/2016 , 2016/2017
, 2017/2018 , 2018/2019
, 2019/2020
[OMI, updated 2019 September 16] A short sequence of ozone depletion during the
2002/03 northern winter showing the difference from the normal.
The annual movies are about 7Mb and were compiled from daily TOMS images until the end of 2005; from
2005/06 they have been compiled from OMI images. The movies begin and end on
the June solstice.
Today's
forecast OMI Antarctic image
The
current area of the hole and
other latest details are available from the NOAA Climate Prediction Center.
Environment Canada have a set of
daily maps showing both northern and southern ozone levels from a variety of
sources.
The Sciamachy uv index
from the ESA Tropospheric Emission Monitoring Internet Service.
Note that west longitude is negative when entering co-ordinates.
Requests for permission to use this data or for further information should be sent to Jon Shanklin who maintains these pages.
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