British Antarctic Survey Ozone Bulletin 02/96 issued 1996 September 10

This bulletin presents total column ozone measurements made using Dobson ozone spectrophotometers. Note that all ozone values are preliminary and are subject to revision from time to time when the instrument constants are re-evaluated. All ozone data is reduced to the Bass-Paur scale as recommended by the WMO.

1. Data from the British Antarctic Survey (BAS) Halley station (76 south, 26 west, on the Brunt ice shelf).

a) Ozone. Routine ozone measurements from Halley station do not start until towards the end of August because the sun is not high enough to permit measurements. The few measurements available suggest that values are around 180 DU, rather lower than in 1995. Data from our long term record for the station indicate normal values of around 300 DU for this period (with a range of 260 DU to 340 DU).

Halley preliminary mean daily total ozone, (DU) Dobson No 103: Instrument constants revised 1996 March 8 (0 indicates no data)

1996 August 1 - 1996 August 29

   0   0   0   0   0   0   0   0   0   0
   0   0   0   0   0   0   0   0   0   0
   0   0   0   0   0 183 184 180 177

Halley provisional monthly mean total ozone (DU)

Period    Aug  Sep  Oct  Nov  Dec  Jan  Feb  Mar  Apr  Year
1995/96   219  160  129  163  253  263  248  247  224  210
1957-72   295  285  300  355  350  320  300  295  285  310

b) Radiosonde data. Stratospheric temperatures at 100 hPa, near the peak of the ozone layer can be used to reflect changes in ozone amount. Stratospheric clouds, which are crucial to the mechanism of ozone depletion, are likely to be present when the 100 hPa temperature is below -80 deg C and may persist whilst the temperature is below -75 deg C. Data from Halley show that the 100 hPa temperature is presently close to the long term mean, at around -83 deg C.

2. Data from the Ukrainian Antarctic Research Centre Vernadsky station (65 south, 64 west on the coast of the Antarctic Peninsula, formerly the BAS Faraday station).

Preliminary ozone values from Vernadsky show mean total ozone values generally around 220 DU during August, but with exceptionally low values below 140 DU on August 4th and also with low values around the 7th and 28th. Day to day variation is around 20 DU. Data from BAS long term records for the station indicate normal values of around 330 DU for this period (with a range of 280 DU to 380 DU). The previous minimum mean daily value recorded during the month was 170 DU in 1992. The August monthly mean of 206 DU is the lowest for that month by a substantial margin, the previous lowest was 236 DU, also in 1992. Early September saw an initial rise to 270 DU followed by a rapid fall to 175 DU by September 5th.

Vernadsky preliminary mean daily total ozone (DU). Dobson No 31: Instrument constants revised 1995 December 14

1996 August 1 - 1996 September 5

 217 206 172 141 178 207 161 177 200 221
 214 218 213 229 211 227 230 225 212 225
 227 235 223 251 221 197 184 177 179 217 198
 223 245 212 181 176

Vernadsky provisional monthly mean total ozone (DU)

Period    Aug  Sep  Oct  Nov  Dec  Jan  Feb  Mar  Apr  Year
1996/7    206
1995/6    237  194  251  228  298  285  287  278  266  258
1957-72   310  330  345  370  345  320  300  295  310  325

3 Information from other sources.

TOVS satellite images from the US NCEP/NWS/NOAA Climate Prediction Center show that intermittent ozone reduction events occurred during the first half of August, with depletion becoming more systematic in the second half. Two of the reduction events occurred over the Antarctic Peninsula around August 4th and 8th and are associated with the very low ozone readings made at Vernadsky. The ozone "hole" now covers most of the Antarctic continent and is centred close to the south pole, but slightly offset towards South America. It is slightly elongated in shape and is rotating with a period of about a month. The axis of elongation last lay along the Antarctic Peninsula around August 29 and will next extend towards South America around September 10. The circumpolar high ozone belt is located at about 50=F8S. NASA's Earth Probe TOMS images give more detailed resolution and the solar elevation now allows the sensor to image the continent north of 80=F8S. These images show that the main region of ozone depletion is currently located near the Peninsula.

If you use or pass on this data please make acknowledgement to J D Shanklin, British Antarctic Survey.

Regards, Jon Shanklin


Jon Shanklin / j.shanklin@bas.ac.uk / British Antarctic Survey, Cambridge, England