BAS ozone bulletin 09/95 issued 1995 Oct 23. Preliminary ozone values from the British Antarctic Survey Faraday station (65 south, 64 west on the coast of the Antarctic Peninsula) show mean ozone values dropping from values of around 300 Dobson Units (DU) at the beginning of August to around 180 DU at the end of September (45% depletion). The first week of October saw a major spring warming event, with a rise in mean total ozone to over 300 DU as the circumpolar high ozone belt moved across the station. Mean values then fell back to around 200 DU in mid October before rising again to around 240 DU at present. Planetary wave activity as the edge of the ozone hole passes over the station is giving day to day variation of around 60 DU. Values are generally above those reached in 1993 and 1994. Data from our long term record for the station indicate that normal values are around 350 DU in mid October (with a range of 290 DU to 450 DU). Faraday preliminary mean daily total ozone, (DU). Revised 1995 October 22 1995 August 1 - October 22 310 276 280 269 293 337 311 281 245 233 239 222 217 221 281 282 284 272 223 228 236 241 230 218 205 214 209 236 222 212 227 211 207 208 247 205 200 188 189 193 156 198 276 251 224 273 232 171 208 164 144 142 220 202 179 247 208 164 157 218 267 285 375 329 322 315 323 294 309 253 175 176 173 147 137 283 289 225 190 179 239 298 271 Faraday provisional monthly mean total ozone (DU) Revised 1995 October 22 Aug Sep 250 205 The mean for September is the second lowest September mean recorded at the station, the lowest being 195 DU in 1994. Preliminary ozone measurements from the British Antarctic Survey Halley station (76 south, 26 west on the Brunt ice shelf) show that mean total ozone values dropped from around 250 DU at the beginning of August to a minimum of 125 DU at the end of September (60% depletion). The decline has now halted and ozone values are rising slowly. Mean values are now around 140 DU, similar to those at the same time last year. Day to day variation is around 20 DU. Data from our long term record for the station indicate that normal values are around 300 DU in mid October (with a range of 270 DU to 350 DU). Stratospheric temperatures at 100 hPa, near the peak of the ozone layer, are slowly rising and are now around -79 deg C; this is 7 degrees below normal and similar to that of the same time last year. Some stratospheric clouds will still be present at this temperature. Halley preliminary mean daily total ozone, (DU) (0 indicates no data) 1995 August 1 - October 22 0 0 0 0 0 0 0 221 228 231 248 244 0 0 0 0 0 0 0 0 0 0 0 0 0 0 202 215 187 215 229 199 204 225 217 224 205 213 189 183 206 210 167 188 187 180 160 141 155 160 142 133 137 141 116 121 133 126 135 117 120 123 131 143 137 112 117 145 177 138 126 118 132 152 132 134 137 159 152 127 133 132 138 Halley provisional monthly mean total ozone (DU) Aug Sep 222 168 TOVS satellite images from the US NCEP/NWS/NOAA Climate Prediction Center show that ozone depletion intensified over September, with the ozone "hole" covering most of the Antarctic continent and centred close to the south pole. Ozone values at Halley and Faraday were a little above those of last year, because the centre of the hole was further away from the BAS stations than in 1994. During the first half of October the hole has become more elongated, with the axis of elongation currently aligned towards the South Atlantic. The axis of elongation is rotating around the Antarctic continent with a period of about a month. This rotation of the "hole" gives rise to the larger day to day variation in ozone amount seen at Faraday, which is sometimes inside and sometimes outside the ozone hole. The edge of the hole clipped the tip of South America between October 12 and 14. If you use or pass on this data please make acknowledgement to J D Shanklin, British Antarctic Survey.