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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 20 12 May 18 .

Situation at 2012 May 3

The 2011 Antarctic ozone hole is over.  The  weak summer circulation is changing to the winter mode,  but ozone gradients remain generally small.   Minimum ozone values are currently around 250 DU and well above the ozone hole threshold.   Maximum values are near 330 DU, well down from peaks above 400 DU in early spring.   The lower stratospheric temperature is falling, and temperatures generally remain a little below the normal for this time of year.  It is too warm for stratospheric clouds to form.

The hole began to form in mid August, and by mid September had reached an area of around 25 million square kilometres, larger than the average for the last decade and remained near this size into early October.  It had shrunk to around 20 million square kilometres by mid October and remained a similar size till mid November, when its size dropped rapidly but remained at a few million square kilometres until mid December.  It  filled by the summer solstice.   Its size from October to mid November was near to or above the record area for the time of year.  The hole became more elliptical in mid October and the edge of the ozone hole passed over the tip of South America and the Falkland Islands, but then returned to a more circular form.  The edge of the ozone hole  passed over the tip of South America around September 26 to 28, October 9, 16 to 19.  The edge again passed over this area from November 7 to 8.  Significant differences between the various satellite analyses of ozone distribution remain.

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.  This year the polar vortex was cold and stable, allowing substantial ozone depletion.  It is still too soon to say that we have had the worst ever ozone hole.

The northern circulation pattern is beginning to enter the summer mode, with peak ozone levels declining.  Minimum temperatures were close to the seasonal extreme in late 2011 and well below the PSC formation temperature, but a spring warming in mid January pushed them above the threshold.  Arctic ozone levels are within 30% of normal, with areas that are higher and lower than the mean.  There was substantial Arctic ozone depletion over the northern winter of 2010/11, particularly in March 2011.   

See the final situation report for last year for information on the 2010 - 2011 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.  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).  

Click on a thumbnail to get the latest graph or high resolution image, which is updated more frequently than the thumbnails.  

zoz1112.JPG (235976 bytes) Halley - Total ozone:   The observing season at Halley began at the start of September with the station already experiencing ozone hole conditions, and mean values around 190 DU.   Relatively less depleted air was over the station in early September, but mean values began to drop significantly and had reached 125 DU (60% depletion) by the end of the month.  Mean values rose during October, though the seasonal daily minimum of 106 DU (65% depletion) was reached on October 4.  Ozone values reached the ozone hole threshold of 220 DU (40% depletion) by the end of November, and peaked at around 300 DU (12% depletion) around Christmas.  Values slowly fell to reach around 260 DU (15% depletion)  in mid April, which was the end of the observing season.  The maximum value reached since the equinox is 314 DU on December 19.  Note: the instrument constants for #73 were revised in 2012 February, and the above values have been updated to reflect the improved calibration.  Dobson 31 began observations on February 4 and became the operational instrument on February 14 when observations with Dobson 73 ceased.  The zenith calibration of #31 needs improvement, so the figures from mid February onwards will be revised when enough data has accumulated. 

r11.JPG (238835 bytes) Rothera -  Total ozone:     Real-time graphs showing current ozone and NO2 levels .   Mean values slowly declined from around 300 DU at the beginning

r12.JPG (111679 bytes) of 2011 to around 285 DU in mid June, though with an excursion to around 270 DU in the first half of March.  Values began to drop quickly in July and there were brief excursions to ozone hole levels on July 1 and at the end of the month.  Mean values had reached 160 DU by mid September, and then slowly declined to reach 140 DU by late October when a rise to 175 DU took place.  Values fell to around 160 DU in November and then slowly rose back to 175 DU before rising rapidly to 310 DU by the end of the month.  The rise continued more slowly and values peaked at around 345 DU in mid December.  Values fell to around 255 DU towards the end of the year as a remnant of low ozone passed over the station, before rising to 300 DU at year end.  They began 2012 at around 295 DU and had slowly declined to 280 DU by mid May, with fluctuations on a timescale of around 20 days.  The lowest daily value recorded this season was 116 DU on September 28.  The highest daily value since the spring equinox is 354 DU on December 12.  Surprisingly, the low values that were seen in early August were not captured by most of the analyses, with only TOAST giving values close to the observed 178 DU. Superimposed on the general trends 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.  Some data was lost following a station power down in mid June and the data between June 16 and 29 may have errors.

foz1112.JPG (2036778 bytes) Vernadsky - Total ozone:    Vernadsky station is run by the (External) National Antarctic Scientific Centre of Ukraine .    The observing season at Vernadsky began in late July, when mean values were around 250 DU (20% depletion).  During August they remained around 240 DU but fell to ozone hole levels in early September and had reached around 180 DU by the middle of the month (45% depletion).  Values varied around this level until late October, before a rapid rise to 240 DU (35% depletion).  Values fell again in November to around 185 DU (50% depletion) in mid month, but then rose, reaching 305 DU (20% depletion) in early December.  A slower rise continued, and values peaked at around 330 DU (5% depletion) mid month.  Values irregularly fell, with occasional rises to near normal levels, to reach around 270 DU (15% depletion) by the end of April.  There were brief sharp rises during the spring period, with daily values reaching 309 DU on September 24, 335 DU on October 29 and a peak of 350 DU on December 13.  The lowest daily value recorded this season was 134 DU on September 28.  Superimposed on the general trends 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.  

nacreous_20070712a.JPG (233412 bytes) 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 have seen displays of nacreous clouds; they were seen from Rothera on June 26, July 5, 30, 31, September 22, October 28.  Those at Halley are of the form described during the IGY as "ultra-cirrus".

zt1112.JPG (269717 bytes) Halley - 100 hPa temperature:   The 100 hPa temperature was generally a little below the normal during the autumn and close to the normal during early winter.  Temperatures during August and September remained roughly around -82°C, and whilst close to the normal early in the period, were 3° below it by the end.  From mid September to early November the temperature rose rather slowly and was substantially below the normal.  There was a more rapid rise until the December solstice, when it reached -46°C, which is some 5° below the normal.  It then rose rather more slowly to reach -42°C in late January, which is near the normal for this time of year.  It is now falling and had reached -60°C by the end of April.  It remained significantly below, and occasionally close to, the normal from September to March.

ft1112.JPG (310233 bytes)  Peninsula - 100 hPa temperature:    The mean 100 hPa temperature in the Antarctic Peninsula  has mostly been below the normal since May.  The temperature is normally at its lowest at the end of August at around -76°C.   At -78°C it was significantly below the normal in the first half of August, but returned to near normal late in the month.  It then dropped back to around -79°C in September.  A slow and irregular warming began in October, becoming more rapid from mid November, with the mean temperature reaching near normal levels around -44°C in early December.  It fell, declining to around -49°C after the solstice, but then slowly rose reaching around  -44°C in early February, close to the normal.  The temperature is now falling and had reached -59°C by the end of April.  A short-lived spring warming occurred at the end of October.  The temperature was substantially below the normal during September, October and November.  There is often large day to day variation because the area is in the edge region of the circumpolar vortex.  

Satellite: (External) 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 2011/2012 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 (External) 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-emphasise 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 (External) CPC plots from NOAA show the (External) current area of the ozone hole .  The Sciamachy (External) 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 range from around 300 DU to just above 450 DU.   The circulation is emerging from the winter pattern and there is currently high ozone over the Siberian Arctic and northern Canada.  The 70 hPa zonal minimum temperature was generally below the seasonal normal from October, and dropped below the PSC formation threshold in December, with record minimum temperatures being set.  January begin with temperatures continuing to set record minima, though rose in mid month to near normal and above the PSC formation threshold.  In early October a few areas of northern Europe were below 250 DU at the normal autumnal minimum of column ozone, and in early December the Iberian Peninsula also experienced similarly low ozone levels.  

The north polar vortex is usually smaller and more disturbed than the corresponding one that forms during the Antarctic winter.  In 2011 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.  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.  There are sometimes significant differences (over 100 DU) between modelled, satellite and ground-based measurements, particularly when there is large variation in total column ozone.  Ozone values over the Arctic during 2009/10 are shown in our Northern Hemisphere TOMS movie .   For more UK information see the DEFRA (External) 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 (External) 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 2011 February 28].
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 2011/2012 for Halley   [Dobson 73, updated 2012 February 24],  Halley   [Dobson 31, updated 2012 April 23] and Vernadsky .  [Updated 2012 May 18]  
Provisional daily mean ozone values for Faraday/Vernadsky and Halley between 1972 and 2011. [Updated 2011 June 24]
Provisional monthly mean ozone values for Faraday/Vernadsky and Halley between 1956 and 2011.
Provisional monthly minimum ozone values for Faraday/Vernadsky between 1972 and 2011 and Halley between 1956 and 2011.
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]

Temperature and Ozone graphs for Halley and Vernadsky/Faraday. [Updated 2012 May 3].  The historic period shown in the inline graphs is for 1957 - 1972.

Stratospheric Temperature
Monthly 100 hPa temperature means for The Antarctic Peninsula and Halley between 1954 and 2011. [Updated 2011 June 24]

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:   
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 and 2012 [updated 2012 May 18] and as real-time graphs showing current ozone and NO2 levels .
Bentham ozone. Provisional values for 1997 / 1998 / 1999 / 2000 / 2001 / 2003 / 2004 [updated 2004 November 5 ]. 

Some background information on Halley , Rothera and Faraday stations is available from BAS. Information about (External) Vernadsky station is also available from the Ukrainian Antarctic Centre. Information about (External) 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 and 2011/2012 OMI, updated 2012 May 11].  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 and 2011/2012 [OMI updated 2012 May 11]  A short sequence of ozone depletion during the 2002/03 northern winter showing the difference from the normal.
These annual movies are now about 4Mb and were compiled from daily (External) TOMS images until the end of 2005; from 2005/06 they were compiled from OMI images. The movies begin and end in June.
(External) Today's OMI global image
The (External) current area of the hole and (External) other latest details are available from the (External) NOAA Climate Prediction Center .
Environment Canada have an excellent set of (External) daily maps showing both northern and southern ozone levels from a variety of sources.
The Sciamachy (External) uv index from the ESA  Tropospheric Emission Monitoring Internet Service.  Note that west longitude is negative when entering co-ordinates.

Contacts

Requests for permission to use this data or for further information should be sent to Jon Shanklin who maintains these pages.

(External) NERC / BAS / MET

© Copyright Natural Environment Research Council - British Antarctic Survey 20 12

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