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.
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 -84 deg C.
Preliminary ozone values from Vernadsky show mean total ozone values generally around 215 DU during August, but with exceptionally low values on August 4th and 7th. 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.
Vernadsky preliminary mean daily total ozone (DU). Dobson No 31: Instrument constants revised 1995 December 14
1996 August 1 - 1996 August 22
217 206 172 141 178 207 161 177 200 221 214 218 213 229 211 227 230 225 212 225 227 235
Vernadsky provisional monthly mean total ozone (DU)
Period Aug Sep Oct Nov Dec Jan Feb Mar Apr Year 1995/6 237 194 251 228 298 285 287 278 266 258 1957-72 310 330 345 370 345 320 300 295 310 325
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. The ozone "hole" covers most of the Antarctic continent and is centred close to the south pole. 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.
If you use or pass on this data please make acknowledgement to J D Shanklin, British Antarctic Survey.
Regards, Jon Shanklin
Data from j.shanklin@bas.ac.uk, formatting by WMC. British Antarctic Survey, Cambridge, England NERC / BAS / ICD / Navigate