British Antarctic Survey
Ozone Bulletin 15/97 issued 1997 December 8



Total ozone values have peaked at Halley and Vernadsky following the spring warming. The ozone hole for this year is over, though values are still 15% below the long term mean. The next bulletin will be issued in early January.


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


a) Ozone. Total ozone values fell from an estimated 300 DU in early July to around 200 DU in mid August. Values rose to around 240 DU towards the end of August but then steadily fell to reach 115 DU in early October. Ozone values rose to around 160 DU late in October and remained near this value until mid November when the spring warming started. Values peaked at around 280 DU in early December. They are however, still well below the long-term mean, with depletion near 15%. Day to day variation is now around 30 DU.


Halley preliminary mean daily total ozone, (DU)
Dobson No 103: Instrument constants revised 1997 December 5.
(0 indicates no data)


1997 August 1 - 1997 December 3

 0 0 0 0 0 0 0 0 0 0

194 0 194 195 213 214 221 215 230 217

0 0 0 0 0 0 215 245 204 188 181

173 186 180 180 214 213 204 190 170 181

187 166 169 156 179 177 144 152 166 171

160 153 135 131 126 138 144 130 121 122

152 122 115 119 121 117 111 114 123 112

112 115 126 119 116 120 122 143 147 161

161 149 173 187 178 165 162 153 146 141 156

152 143 154 152 171 160 160 164 159 159

161 159 161 182 181 187 202 225 237 248

262 270 248 241 266 276 284 308 288 272

278 281 275


Halley provisional monthly mean total ozone (DU)


Period Aug Sep Oct Nov Dec Jan Feb Mar Apr Year
1997/98 209 164 137 208
1996/97 172 155 149 181 260 278 265 245 242 216
1995/96 219 160 129 163 253 263 248 247 224 210
1957-72 295 285 300 355 350 320 300 295 285 310

Note that August and April do not have observations on every day, and that the routine measurement season is now longer than it was in 1957 - 72. Measurements made at the start of the season are of lower accuracy than in mid summer due to the low solar elevation. Gif images showing the data are available on the BAS ozone web-page.

b) Radiosonde data. Data from Halley show that the mean 100 hPa temperature rose from winter values of -83-deg C in mid October and reached a plateau at -75-deg C by the end of the month. The rapid spring warming began in mid November, and peaked in early December, but the 100 hPa temperature is still 6 deg C below the long term mean. Stratospheric clouds, which are instrumental in the mechanism of ozone depletion, have been observed from the station on August 1, 3, 6, 7, 8, 10, 13, 14, 15, September 3, 4, 21, 22, 26, 27, 30 and October 2, 3, 6 and 7. The display on August 10 was particularly vivid and that of September 30 showed classic development after sunset. The display on October 2 showed similar features to those seen in noctilucent clouds.



Data from the British Antarctic Survey (BAS) Rothera station (68-deg south, 68-deg west on Adelaide Island).


a) Ozone. Ozone measurements from Rothera are made using a SAOZ (Systeme d'Automatique Observations Zenithales) spectrometer. This is a research instrument, but the daily ozone values are available. These show a generally similar pattern of variation to that seen at Vernadsky, though day to day variation is a little less and minimum values are a little lower.

Rothera preliminary mean daily total ozone, (DU)
(0 indicates no data or data not available)


1997 August 1 - 1997 December 2


299 216 227 199 239 211 218 299 285 270

301 297 309 312 304 266 279 272 256 259

259 294 287 292 266 266 297 304 295 270 236

230 199 214 248 259 244 216 194 204 203

200 196 172 205 283 338 351 359 330 297

257 200 193 241 216 186 206 204 201 211

181 159 152 133 131 145 157 153 133 136

120 137 134 138 153 187 199 222 290 346

357 329 348 360 340 324 284 201 156 153 142

130 133 150 157 168 183 157 155 145 146

141 150 153 175 186 218 238 271 312 323

314 318 306 275 278 321 310 310 299 302

292 277


b) Stratospheric clouds. Nacreous or mother-of-pearl clouds are regularly seen from stations along the Antarctic Peninsula between early May and October, with a peak in July. There is some evidence that their frequency of occurrence has increased since the mid 1950s. This year they have been observed from Rothera on June 8, 10, 13, 15, July 4, 17, 21, 23, August 4, September 1, 3 and October 14.


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


Running mean total ozone values fell from an estimated 350 DU in early July to 240 DU in early August. Since then the running mean has varied between 150 and 340 DU (55 - 5% depletion) under the influence of strong planetary waves with a period of around a month. Day to day variation is currently around 40 DU. Particularly low values were recorded on August 2nd, when the station was affected by one of the ozone reduction events associated with the forming ozone hole. Very low values occurred around September 13th, October 4th, 11th and November 1st (142 DU is the lowest November daily mean on record for the station) when the centre of the ozone hole passed near the station. Very high values near 370 DU were recorded on September 18th and October 21st when the circumpolar high ozone belt was over the station. The spring warming produced a peak of around 300 DU, which is 15% below the long term mean.


Vernadsky preliminary mean daily total ozone (DU).
Dobson No 31: Instrument constants revised 1997 December 5


1997 August 1 - 1997 December 3


 271 212 234 227 231 232 232 283 278 261

256 259 277 287 287 255 241 237 236 250

237 299 293 297 258 289 316 314 307 302 255

236 199 207 257 256 252 234 214 213 210

202 184 154 206 271 356 370 373 372 287

269 214 186 255 250 218 246 263 265 243

227 198 176 150 151 161 201 182 159 170

152 161 158 150 156 194 237 234 330 370

364 356 365 364 343 343 322 275 195 186 172

143 152 164 182 197 229 222 170 164 154

157 169 167 166 188 198 229 278 320 321

319 324 296 295 332 327 315 301 317 308

311 282 278


Vernadsky provisional monthly mean total ozone (DU)


Period Aug Sep Oct Nov Dec Jan Feb Mar Apr Year
1997/98 265 249 232 237
1996/97 217 205 263 226 271 304 279 277 294 260
1995/96 237 194 251 228 298 285 287 278 266 258
1957-72 310 330 345 370 345 320 300 295 310 325

b) Radiosonde flights at Bellingshausen resumed in mid November and show a rapid rise in temperature at the 100 hPa level, though values are still below the long term mean for the time of year.


4. Information from other sources.


TOVS satellite images from the US NCEP/NWS/NOAA Climate Prediction Center and EP/TOMS images from the US NASA/GSFC show the development and decline of the ozone hole. Ozone values are now at their summer high over the Antarctic continent and the ozone hole is over for this year. The satellite images show that the edge of the ozone hole passed over the tip of South America and the Falkland Islands on September 13/14, October 12/15, October 31/November 5 and November 10/13 and just clipped the area on September 23/24 and October 4/5.



Further information is available on the BAS ozone web page, which contains earlier bulletins, data, graphs and general ozone information. The url is:
http://www.nbs.ac.uk/public/icd/jds/ozone


Note that all ozone values in this bulletin are preliminary and are subject to revision from time to time when the instrument constants are re-evaluated. Final data will be archived with WOUDC, Toronto in due course, but preliminary data back to 1973 are available from BAS on request. All Dobson ozone data is reduced to the Bass-Paur scale as recommended by the WMO. If you use or pass on this data please make acknowledgement to J D Shanklin, British Antarctic Survey.

 

Best wishes for a happy Christmas and New Year.

 

Jon Shanklin