[BAS Science]   [BAS home]   [ Met home]	Meteorology and Ozone Monitoring Unit

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 2014 June 23.

Antarctic Situation at 2014 June 23

Antarctic ozone today:  The ozone distribution is that of winter with ozone amounts increasing around the Southern Ocean and lower amounts over the continent.   Highest ozone values are around 430 DU over the Indian Southern Ocean, with lowest values below 240 DU over Coats Land.  There are significant differences between the various satellite measurements.  Stratospheric temperatures are still cooling, and are widely below the threshold for Polar Stratospheric Cloud formation.

The 2013 ozone hole:  The 2013 ozone hole ended in mid November.  The temperature of the lower ozone layer rose rapidly in a "Spring warming event" in late October and Polar Stratospheric Clouds (PSCs) disappeared from within the polar vortex.   The ozone layer temperature dropped below -90°C on occasion during the late winter.  On a few days in early August,  in mid and late September new record minima were set.  It was significantly cooler than the long term mean until late August, and generally remained colder than the long term mean until mid October.  The area with temperatures colder than the PSC formation temperature of  -78°C was around average until mid September, reaching a broad peak of around 25 million square kilometres from mid July to late August.   The area dropped below average in mid September, and declined to near zero by mid October, a little earlier than average.  The Spring Warming pushed temperatures over the Antarctic Peninsula well above the long term average for the time of year.  The 2013 winter polar vortex was generally a little larger than the average over the last decade, reaching a peak of around 33 million square kilometres in late August.  According to NOAA SBUV measurements the ozone hole began to form in mid August and was at its largest at around 21 million square kilometres from mid to late September.  The area of the hole had shrunk to zero by mid November.   The hole was generally larger than in 2012, but smaller than the average of the last decade.  It was an earlier end to the ozone hole than the average for the last decade.  The edge of the ozone hole briefly touched the tip of South America on September 16, October 12 and more extensively from October 15 to 17.  

See the final situation report for last year for information on the 2012 - 2013 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).  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.

Observations from Halley since 1993 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, 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.  The 2013 ozone hole however begins to suggest that unless there is a major perturbation of the stratosphere, we may already have seen the worst ever ozone hole.  This is because meteorological conditions in 2013 were favourable for larger than average ozone depletion, but this did not occur.

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.  Initial Dobson measurements made at the end of August give values of around 195 DU and mean daily values had dropped to a minimum of around 145 DU by early October (50% depletion).  They rose slowly in the first half of the month to 180 DU, and then more rapidly to reach around 310 DU in early November and remained near this level until early December (10 - 15% depletion).  Values fell slowly to reach around 255 DU (15% depletion) by mid April.  The lowest daily value this season was 127 DU on September 23, the highest was 338 DU on November 29.  Halley also has a SAOZ spectrometer, and measurements with this, which began on August 3 and ended on May 8, suggest that ozone values were around 230 DU in early August and had dropped to a minimum of around 125 DU by the end of September.  Values began rising in October, with a more rapid rise starting in mid month to reach around 290 DU in early November.  Values remained near this level until early December but had fallen to around 255 DU towards the end of the year.  They have remained within about 10% of 265 DU during 2014.  The lowest SAOZ daily value this season was 106 DU on September 23 and the highest was 308 DU on November 5, 6 and 15.  SAOZ values from day 231 onwards were revised on November 22 following a change in computing procedure to include measurements made at a higher solar altitude.

Rothera - Total ozone:    Real-time graphs showing current ozone and NO2 levels.  2013 began with mean values not far from 280 DU, where they remained until late May 2013.  They rose to around 330 DU by the winter solstice, the highest at this time of year for a decade.  Values dropped, with brief excursions to ozone hole levels on July 19, 20 and August 1 to 3 and 14, before dropping below the ozone hole threshold of 220 DU at mid month.  By mid October mean daily values had dropped to around 150 DU, but then began to rise rapidly.  They peaked at around 365 DU in early November but then dropped to around 255 DU in late November.  They rose to a peak of around 305 DU in early December and had dropped to around 295 DU near the end of the year.  Mean ozone values declined slightly to around 280 DU by 2014 May and increased to around 300 DU by the winter solstice.  The lowest daily value  this season was 124 DU on September 29 and the highest was 383 DU on November 4.  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.  Data is missing from November 12 to 15 and from December 23 to January 6 due to a computer failure.

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 mean ozone values were around 280 DU; by late September they had fallen to a broad minimum of around 190 DU (40% depletion).  They began to rise quickly in mid October and reached a peak of around 385 DU in early November (comparable to normal).  They then fell substantially to around 280 DU (30% depletion) in late November, before recovering to a peak of around 320 DU (10% depletion) in early December.  Values slowly declined and reached around 265 DU (10% depletion) by the end of April.  The lowest daily value this season was 152 DU on September 15, whilst the highest was 399 DU on November 6.  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.   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 observering season has now ceased.

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".  This year, Rothera saw the clouds on September 2 and 3.

Halley - 100 hPa temperature:  The lower ozone layer remained near its winter temperature until late September with the 100 hPa temperature around -84°C, a couple of degrees colder than the normal.  The temperature rose slowly to reach -78°C in mid October, then more rapidly to reach -49°C in early November, which is several degrees warmer than the normal.  It had fallen back to -51°C by late November, 2° colder than the normal, but then rose to peak at around -41°C (near normal) in early December.  It is slowly cooling and has reached around -80°C.  The temperature was cooler than the normal between August and late October, from late November until early December, from mid December until late March and from mid April.

Peninsula - 100 hPa temperature:   The mean 100 hPa temperature in the Antarctic Peninsula  was below the normal during the winter and early spring.  The temperature had cooled to around -84°C by the end of August, about 8° below the normal for this time of year.  It rose slowly until mid October, remaining colder than the normal, when a more rapid rise commenced and the temperature peaked at around -39°C in early November, some 16° above the normal.  Daily values were amongst the highest temperatures on record for this time of year.  The temperature then dropped to around -56°C later in November, 18° below the normal, before recovering to near normal by early December.  They reached a peak of -43°C in late December but fell to -45°C early in the new year where they remained until early February.  The temperature is falling and has reached -70°C.  The temperature was significantly cooler than the normal between August and mid October, from late November until early December and since mid April.  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.

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 2013/2014 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-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 CPC plots from NOAA show the current area of the ozone hole.  The Sciamachy uv index from the ESA  Tropospheric Emission Monitoring Internet Service shows the exposure risk at any location.