BAS ozone bulletin 16/94 issued 1995 May 16.
This bulletin gives a resume of the provisional ozone
data for 1994/95 from the British Antarctic Survey
Faraday station (65 south, 64 west on the coast of the
Antarctic Peninsula) and Halley station (76 south, 26
west on the Brunt ice shelf), obtained using the Dobson
ozone spectrophotometer.
The definitive instrument and
zenith calibration values have not yet been determined.
A daily mean value is given, using all the observations
for that day, assigning equal weight to each.
Note that
all values are preliminary and are subject to revision
from time to time.
The final daily values may differ
from those given here, but should not differ from them by
more than 5%.
Some experimental zenith observations at
low solar elevations are included, these have lower
accuracies than normal observations.
Monthly mean values
are given for each station with pre ozone hole means for
comparison.
Preliminary mean ozone values from Faraday show that mean
ozone values at the end of the winter were around 290 DU
dropping to a minimum of around 160 DU by mid October
(55% depletion).
This is the steepest decline recorded
at this station, and the minimum mean values were about
40 DU below those at the same time last year.
The mean
for September is the lowest September mean recorded at
the station; 133 DU recorded at the end of the month is
the lowest ever September mean daily value.
Individual
values of 130 DU in early October represent nearly 65%
depletion and are the second lowest on record for the
station.
A strong spring warming episode occurred
between October 20th and 28th, with a very rapid rise to
400 DU on October 22nd; this is the earliest the warming
has occurred for several years and is also the steepest
rise (some 250 DU in three days).
Following the event
mean values dropped to 180 DU (50% depletion), and then
slowly rose again, reaching 230 DU by November 23rd.
The
final spring warming occurred between November 21st and
23rd with mean ozone values rising rapidly to around 340
DU by the end of November.
The November monthly mean is
the second lowest on record.
Values in early December
were near normal at around 360 DU, but were generally
below normal throughout the late summer and autumn.
Faraday preliminary mean daily total ozone (DU)
Dobson No 31: constants revised 1995 April 18
1994 Aug 1 - 1995 April 30
277 270 288 301 289 297 257 247 294 233
268 264 278 275 286 306 267 267 282 254
293 306 265 304 258 205 209 216 218 242 260
310 265 233 228 196 211 241 225 220 228
211 221 160 158 151 175 161 187 188 171
192 213 181 183 159 180 189 141 138 126
123 124 141 191 268 231 195 169 146 145
134 134 141 154 156 139 129 140 148 217
360 392 354 394 375 361 334 283 209 171 154
158 157 192 155 172 187 172 173 207 204
194 212 179 196 199 206 193 198 230 213
209 269 319 284 289 309 339 345 328 344
335 347 364 352 360 358 354 361 341 355
347 349 348 350 350 332 337 336 315 318
321 331 324 317 297 279 304 323 306 309 289
299 303 285 292 299 271 255 270 285 298
311 313 298 320 305 301 295 299 309 323
308 288 294 285 299 279 303 300 284 291 295
294 292 293 272 279 286 305 289 316 314
294 317 310 289 298 285 277 274 252 237
249 256 259 279 293 293 268 293
305 302 307 278 314 324 319 306 306 304
294 296 319 334 320 307 280 262 281 294
302 283 268 287 292 279 273 274 287 270 268
268 266 266 285 283 248 281 295 290 276
281 297 299 280 268 299 291 305 301 317
328 323 335 317 271 283 228 237 229 273
Faraday monthly means and minima:
1994/95
long term
mean
min
mean
Aug
267
205
330
Sep
195
126
330
Oct
213
123
350
Nov
228
155
375
Dec
333
279
355
Jan
295
255
335
Feb
284
237
315
Mar
295
262
305
Apr
284
228
310
Preliminary ozone measurements from Halley show that mean
ozone values dropped from around 180 DU at the end of
August to 105 DU in early October (65% depletion), then
slowly rose to reach 160 DU by November 7th.
A minor
peak occurred between November 7th and 17th, with a
maximum of 230 DU on the 11th, followed by a decline to
185 DU.
The spring warming commenced on November 24th
with ozone levels peaking at around 350 DU in late
November and then slowly declining.
The monthly means
for September and October are between those of 1992 and
1993.
Mean values throughout the summer and autumn were
significantly below those of the long term mean and
throughout the season no daily values exceeded those of
the long term mean.
The data from 1956 - 1994 suggest that the mean for
October 1995 will be around 120 DU, with minimum values
below 100 DU.
The temperature at 100 hPa rose slowly from the winter
value of around -82 deg C in early October to reach -67
deg C by November 22nd (some 15 degrees below normal).
The final warming then took place with the temperature
reaching near normal values of around -40 deg C by the
end of the month.
The temperature then slowly declined,
reaching -60 deg C by the end of April.
Halley preliminary mean daily total ozone, (DU)
Dobson No 103: constants revised 1995 April 19
(0 indicates no data.)
1994 Aug 1 - 1995 April 30
0 264
0 203 174 159 159 169
210 172 176 173
0 181 166 176 173 207
174 168 171 138 136 146 144 153 159 156
150 143 131 119 120 145 162 188 125 117
107 103
98 125 108 114 116 109 109 105
101 108 114 118 116 123 125 122 127 133
136 140 146 141 136 135 127 141 152 157 152
152 146 167 163 165 154 160 193 187 219
234 228 218 202 201 193 186 203 187 204
210 207 209 234 280 303 321 320 330 353
353 344 337 342 341 341 336 333 345 355
349 342 328 320 320 317 316 300 309 294
288 286 291 304 303 299 306 291 300 288 294
286 285 298 302 301 302 298 304 282 288
285 290 284 280 273 263 264 269 265 285
263 279 284 264 251 268 267 265 270 256 272
271 276 281 269 286 282 272 274 280 270
258 275 265 251 244 262 252 254 260 270
295 294 278 274 276 273 278 283
293 280 267 281 282 263 290 275 271 290
275 277 288 281 289 294 292 289 264 274
273 282 288 255 257 252 242 250 266 285 266
270 261 277 277 288 256 254 255 214 227
266 271 270 246 242
271 254
Halley monthly means and minima
1994/95
long term
mean
min
mean
Aug
(188)
159
300
Sep
158
117
300
Oct
124
98
300
Nov
218
146
360
Dec
318
286
350
Jan
279
251
330
Feb
272
244
310
Mar
275
242
310
Apr
(259)
214
300
The ozone values from Halley and Faraday are consistent
with a hole of greater maximum extent than in 1993, but
slightly shallower.
NASA GSFC images from Meteor-3/TOMS
and radiosonde data suggest that the edge of the hole was
over the tip of South America and the Falkland Islands
between October 11th and 21st, and was close to the
region between October 29th and November 13th.
The
Falkland Islands now consider the ozone hole a major
threat to health following cases of severe sunburn during
this event.
If you use or pass on this data please make
acknowledgementtoJDShanklin, BritishAntarctic
Survey.
Regards, Jon Shanklin
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