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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 2016 June 27.
Antarctic ozone today: The ozone distribution is that of early winter with ozone amounts lowest over the continent but building around it as the polar vortex becomes established. Ozone values currently range from around 250 DU to above 400 DU. They are lowest over central Antarctica and highest over the Southern Ocean in the Pacific sector. There are significant differences between the various satellite measurements. Temperatures in the ozone layer are still cooling from their summer peak and are generally close to the normal. Through much of the ozone layer over the continent they are now below the threshold for Polar Stratospheric Cloud (PSC) formation, so that it is possible for some ozone depletion to take place. Temperatures are above the threshold over Wilkes Land, as is usually the case.
The 2015 ozone hole: Meteorological conditions were favourable for the creation of a significant ozone hole in 2015, with a stable polar vortex and a cold stratosphere. Ozone hole levels were briefly reached over the Antarctic Peninsula on August 5 and over Halley the next day in a dynamic event. Significant ozone depletion over the continent began in mid August as the sun returned. Depletion became more widespread by September, exceeding the mean for the last decade and greater than in the last couple of years. Ozone declined by about 1% per day near the centre of the ozone hole. The ozone hole peaked at some 26 million square kilometres in the first half of October. It was the largest ozone hole ever for the time of year in the second half of October. It became more elliptical in early November, affecting the Falkland Islands and South Georgia over November 4 and 5, and again around November 20 to 23. It remained amongst the largest of the decade into mid December. The polar vortex was the largest over the past decade in the upper part of the ozone layer from July to October and the area with PSCs was also larger than average during this period. At lower levels the vortex was largest ever, by a considerable amount, from October and into December. Some volcanic aerosol from the eruption of Calbuco in southern Chile in late April 2015 reached Antarctica and this may have lead to additional ozone depletion.
PSCs were visible from the UK on February 1 and 2
and again at the end of the month.
The dense form known as nacreous or mother-of-pearl clouds was most noticed in
the earlier displays (eg
this shot by Alan Tough from Alloa), however diffuse clouds with the appearance
of high stratocumulus were more widespread.
See the final situation report for last year for information on the 2014 - 2015 season.
Notes: 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.
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. 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. The provisional Halley 2015 minimum value was lower than that of
2014, 2013 and 2012. The low value in 2015 was mostly due to the
prevailing meteorological conditions, but may also have been influenced by the eruption from Calbuco
in southern Chile.
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 begins at the end of August and
ends in mid April. Note: 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. The preliminary Dobson values given here
should therefore be
treated with some caution and will be revised. During the
winter, Dobson observations using the Moon as a light source are possible and
measurements in late June and early July showed values dropping from around 330 DU to 230 DU as
the polar vortex rotated.
Further observations at the next lunation
showed values dropping from around 300 DU in late July to 250 DU in early
August. When moon and solar observations became possible in the last
ten days of August ozone values were around 255 DU and they dropped to around
125 DU by mid October (60% depletion), a decline of about 1% (3 DU) per day.
Values slowly rose, with occasional pauses, reaching around 280 DU (15%
depletion) in early January. Values since then slowly declined to around
240 DU (20% depletion) by mid April, when routine observations ceased.
Lunar observations in May gave values around 230 DU, whilst those in June were
higher at around 240 DU. Mean Dobson ozone values
were below the
ozone hole threshold from August 31 until December 1. The lowest daily value this
season was 116 DU on October 13, the lowest ozone value here
since 2011.
The
mean for November was the second lowest for the month on record. The
highest daily value was 302 DU on January 5.
Halley also has a SAOZ spectrometer, and measurements with this
began in early August. Surprisingly,
these early measurements suggested that ozone amounts rose from around 200 DU in
early August to around 270 DU by mid month. The low value around August 6
and this broad increase is confirmed by OMI data, suggesting a dynamic event
that generated substantial ozone loss. Ozone values fell to reach around
110 DU in mid October and then rose slowly to mid November and then more quickly
to around 260 DU at the end of the year. They remained within 15 DU of 250 DU
during 2016 until the sun set in early May. The lowest SAOZ daily value this season
was 104 DU on October
14. Daily SAOZ values dropped below the ozone hole threshold on August 25
and remained there until December 10. In general mean
Dobson observations look to the north, whilst mean SAOZ observations look
towards the south.
Rothera - Total ozone: Real-time
graphs showing current ozone and NO2 levels. Mean ozone values
slowly fell from around 300 DU at the beginning of 2015 to around 270
DU
by early May. Values then rose to a peak of around 330 DU in early
July, then dropped rapidly to reach ozone hole levels by early September.
They fell more slowly and variably, reaching around 165 DU in mid
November, with minima around 170 DU in mid September and around 160 DU in mid
October. From mid November to the end of the month they rose rapidly to
reach around 280 DU, peaking at 290 DU in early December. They have remained
within 20 DU of 290 DU during the first four months of 2016. They fell to
around 250 DU in early May and had risen to around 300 DU by the solstice. Daily
values were briefly below 220 DU on August 5 and again from August 22 to 25.
Mean values were below the ozone hole threshold from September 5 to 29 and from
October 4 to November 23. The lowest SAOZ daily value this season
was 126 DU on November 3. The highest spring time ozone was 344 DU on
December 8, though
361 DU was reached in June. 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.
The observing season at Vernadsky began in late July, when ozone values
were around 300 DU. Mean values declined slowly from around 290 DU at the
beginning of August (close to the normal) to around 210 DU (45% depletion) in
mid November. Within this slow decline there were significant variations,
with a minimum of around 200 DU in mid September (40% depletion), a maximum of
around 300 DU (10% depletion) at the beginning of October and a minimum of 210
DU (40% depletion) in mid October. Values rose rapidly from mid November
to reach a peak of around 340 DU (10% depletion) at the end of the month.
Values declined to around 295 DU (15%
depletion) by the end of the year. They were within 20 DU of
295 DU during the first part of 2016, slowly declining to around 270 DU
by the time observations ceased in late May. The lowest daily value this season
was 160 DU on
November 3. The highest values were 378 DU on September 30 and 377 DU on
December 8. 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, 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.
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". During 2015 Rothera saw the clouds on July 1, 7, 21, August 3, 12, 13, 24, 25. The 2016 season started early at Rothera with a sighting on May 14.
Halley - 100 hPa temperature
: The stratosphere cooled
over the 2015 winter, with
the 100 hPa temperature falling below -80°C. At the beginning
of August it was around -85°C, a little cooler than the normal, and it rose,
initially slowly, then more quickly to a peak of around -41°C in early January,
a little cooler than the normal. It is now cooling and had reached -75°C
by mid June.
It was a little
cooler than the normal from January to mid March. The mean for 2015 June
was a little below normal, whilst July was less variable than usual and the
second coldest on record. Overall the
August temperature was near to the normal, but more variable than usual.
The monthly means for October and November were the coldest on record and it was
still well below the normal in December. The mean for 2016 May was a little
cooler than the normal.
Peninsula - 100 hPa temperature Satellite: Satellite
imagery gives a global perspective on the ozone hole, though there are
notable differences between the different satellites, demonstrating the need for
verification by ground based stations. Our
2015/2016 Antarctic ozone hole movie is produced from OMI images, which are generally well calibrated
with respect to ground based measurements. The NCEP and KNMI analyses
are shown on the Canadian
Met Service daily ozone maps pages. The KNMI model is generally better at
analysis and forecasting in the Antarctic. In general the NCEP analysis in
the Southern Hemisphere tends to over-emphasize ozone depletion and the forecast
further increases the amount of depletion, but on occasion (for example in early
August 2011) also ignores real
ozone depletion. The SMOBA and TOAST analyses both use SBUV and TOVS data, but the TOAST algorithm
may at times over-estimate ozone depletion. US NWS CPC
plots from NOAA show the current
area of the ozone hole, though note that this is often a preliminary plot. The Sciamachy uv
index from the ESA Tropospheric Emission Monitoring Internet Service
shows the exposure risk at any location. Arctic:
Ozone values across the Arctic and temperate parts of the Northern Hemisphere
are generally high, relatively uniform, and declining and range from around 290 DU to
just below 400 DU. Ozone values over the UK are around 330 DU.
Temperatures are well above the PSC formation threshold. During January the Arctic stratosphere
was near its coldest for the winter and
its temperature was generally much colder than average for this time of year,
with minimum values close to or below the long term minimum, leading to the
development of PSCs.
A
short lived
spring warming event took place in early February, but temperatures remained colder than the normal for the
time of year. Significant ozone
depletion took place as the sun returned, though values did not drop below the
220 threshold for an ozone hole. It would be worth setting a different
limit for the Arctic as a proportionally greater depletion is required here to
meet the threshold which was set for the Antarctic. A second warming
event took place in early March, this time pushing stratospheric temperatures
above the PSC formation threshold. The north polar vortex is usually smaller and more disturbed than the
corresponding one that forms during the Antarctic winter.
In 2010/11 a
generally more stable than usual Arctic vortex allowed stratospheric
temperatures to drop below the PSC formation threshold for a substantial period
over the northern winter. Warmings occurred in early
January and early February, however parts of the Arctic
ozone layer within the vortex remained cold enough for
stratospheric clouds to form until early April, with
temperatures substantially colder than the normal. With large amounts of
clouds sunlit, ozone depletion reached
its greatest towards the end of March. Ozone values
at Lerwick dropped to 249 DU on 2011 March 29, when the major depletion event passed
near the UK, but values
across the UK returned to near normal by mid April. The major spring warming of the stratosphere occurred
in early April and temperatures from then on were then too warm for PSCs to
exist. By contrast the 2012/13 vortex was very unstable with stratospheric warmings
occurring in
early and late December 2012. Temperatures had warmed above
the PSC formation threshold in late December and were at or near record levels in 2013 January.
In 2015/16 the vortex was again very cold and
stable and in early February the vortex elongated south across the UK.
Spectacular displays of PSCs and nacreous clouds were seen across the UK on
February 1 and 2; good views were had from Cambridge. Ozone depletion
occurred, with unusually low values recorded on January 31/February 1, for
example 224 DU at Reading on February 1. The vortex
elongated again towards the end of the month, and further clouds were seen from
parts of the UK, with 240 DU recorded at Lerwick on February 29.
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 2015/16 are shown in our Northern Hemisphere TOMS 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. 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 recent
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
2013 December 2]. Provisional daily mean ozone
values for 2015/2016 for Halley
[Updated 2016 June 27] and Vernadsky. [Updated 2016 June 3].
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 2016 February 26, but the daily means may still have errors up to 10%, particularly when
ozone values or the solar elevation are low. These preliminary Halley values
should therefore be treated with some caution. The instrument constants
for Dobson 123 at Vernadsky were revised on 2016 April 4. Temperature
and Ozone graphs for Halley and Vernadsky/Faraday. [Updated 2015 October
23].
The historic period shown in the inline graphs is for 1957 - 1972. Rothera - 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]. Rothera - Ozone & nitrogen
dioxide: 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
[OMI, updated 2016 June 27]. A short sequence of the 2001
ozone hole. Requests for permission to use this data or for further
information should be sent to Jon Shanklin who maintains
these pages.
© Copyright Natural Environment Research Council - British Antarctic Survey
2016
:
The mean 100 hPa temperature for June was near normal, whilst that for
July was colder than average. It was around -76°C during August, a little
cooler than the normal. It fell to around -80°C, significantly colder than
usual, in mid September but then rose to around -71°C (near the normal) by the
beginning of October. It fell to reach -77°C after mid month, but slowly
rose to -70°C by mid November, which is some 22° colder than the normal.
Later in the month it rose rapidly to -51°C, and then more slowly to reach -50°C
in early December, but fell to -58°C in mid month, which is some 15° colder than
the normal. It finally rose to the summer peak at the end of the
year, reaching -43°C, very close to the normal. It is now cooling,
generally remaining a little below the normal and had dropped to around -65°C by
mid June. The mean for May was the coldest on record, with particularly low
temperatures on May 27. There is often large day to day variation because
the area is in the edge region of the circumpolar vortex. The
temperature is usually lowest in late August.
Background and related material
Ozone bulletins
Ozone data
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 I 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.
Provisional daily mean ozone values for Faraday/Vernadsky and Halley between 1972 and 2013 April. [Updated 2013 June 24]
Provisional daily mean ozone values for Vernadsky in
2013/14 , 2014/15 ,
2015/16.
Provisional daily mean ozone values for Halley in
2013/14 , 2014/15 ,
2015/16.
Provisional monthly mean ozone values for Faraday/Vernadsky and Halley between 1956 and 2015 December.
Provisional monthly minimum ozone values for Faraday/Vernadsky between 1972 and 2015 April and Halley between 1956 and 2015 April.
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 , 2014 ,
2015 , 2016 [updated
2016 May 16,
processing revised 2013 November 22] and as real-time
graphs showing current ozone and NO2 levels [Not yet available].
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 [updated 2016
June 27]
and as real-time
graphs showing current ozone and NO2 levels. Data is missing between
2013 December 23 and 2014 January 6.
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.
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
[OMI, updated 2016 June 27]
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 in June.
Today's
OMI global image
The current
area of the hole and other
latest details are available from the NOAA Climate Prediction Center.
Environment Canada have an excellent 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.
Contacts
