BAS Ozone Bulletin 02/01
(Annual summary)
This is the second and final
ozone bulletin for the 2001/02 season.
Frequent updates on ozone observations at Halley, Rothera and Vernadsky
are posted on the BAS ozone page at http://www.antarctica.ac.uk/met/jds/ozone/
during the observing season.
The 2001 ozone hole reached an area of
over 25 million square kilometres at its maximum in mid September and remnants
lasted until the summer solstice. Minimum
ozone values were measured in early October.
Autumnal ozone values
were below the normal.
Satellite
imagery gives a global perspective on the ozone hole. Our 2001/2002 ozone hole movies, produced from TOMS images,
currently cover June 2001 to mid May 2002.
Stratospheric clouds were sighted from Vernadsky, Rothera and Halley.
The ozone hole in 2002/03 is likely to be
similar to this year’s, with remnants of the hole persisting well into December
2002. Ozone depletion over the
Antarctic Peninsula is likely to be more severe than in 2001/02.
1. Data from the British Antarctic
Survey (BAS) Halley station (76-deg
south, 27-deg west, on the Brunt ice shelf).
a)
Ozone. Ozone measurements in the first half of
August are made using moonlight and are of very low accuracy. In September values were dropping
at around 2 DU per day from around 180 DU at the beginning of the month. From the equinox to late October values were
around 125 DU, which is 60% below the normal.
The minimum daily mean recorded this year was 116 DU on October 3. Maximum values were reached in late
December, though at around 290 DU they were 25% below and over a month later
than the pre-ozone hole peak. The
highest daily mean was 317 DU on December 23.
Thereafter values declined at around 0.6 DU per day until early March,
giving values around 245 DU, nearly 20% below the normal. At the close of the observing season values
were around 250 DU.
Halley preliminary mean daily total ozone, (DU)
Dobson No 103: Instrument constants revised 2001 October 26.
(0 indicates no data)
2001 August 1 – 2002 April 15
0 223 229 234 223
210 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
0 0 0 0 0
0 168 164 172 184
174
158 158 144 144 137 146 148 142 125
121
120 126 144 136 133 144 127 161 169
136
121 116 120 125 135 132 127 130 147
132
129 130 136 130 125 120 146 137 132
123
138 139 152 142 134 140 140 173 176 222
186
196 179 169 173 177 160 160 160 160
164
157 172 186 167 164 180 194 190 247
283
275 203 248 282 290 269 311 273 290
246
204 201 197 301 310 281 250 241 222
214
255 239 252 258 248 250 268 285 281
301
272 317 315 284 294 292 288 282 283 269
266
255 274 305 280 300 273 286 290 309
298
292 294 291 289 275 276 280 279 287
289
278 279 283 280 283 285 282 278 261 264
263
264 257 260 265 273 264 285 250 250
265
264 269 278 279 274 267 267 258 255
259
256 260 272 264 257 250 229
227
242 248 228 234 247 254 257 261 244
248
241 241 251 248 241 229 237 238 262
263
273 273 267 240 251 243 239 218 218 251
243
239 256 270 255 246 245 262 249 244
258
259 231 225 268
Halley provisional monthly mean
total ozone (DU)
Period Aug Sep Oct Nov Dec Jan Feb Mar Apr Year
2001/02 224 148 138 209 265 283 263 246 250 225
2000/01 179 151 137 267 299 286 261 251 245 231
1999/00 205 172 143 172 254 281 258 250 256 221
1998/99 221 162 140 183 255 272 259 254 267 224
1997/98 218 171 141 210 286 267 262 264 261 231
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 or use
of moonlight. Gif images showing the
data are available on the BAS ozone web-page.
b)
Radiosonde data. The 100 hPa temperature at Halley
remained at winter values of around –83°C until late October. It rose to reach a broad maximum of around
–43°C in late January, some 3° cooler than the normal and nearly a month later.
The temperature was below the normal from early September until late March.
2. 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 research instrument has a preliminary
calibration such that it reads about 15% low compared to Dobson measurements at
100 DU, and is in agreement at 300 DU.
The mean daily total ozone values generally show a similar pattern of
variation to that seen at Vernadsky, though day to day variation does not show
such pronounced wave activity and minimum values are a little lower.
Rothera preliminary mean daily total ozone, (DU)
(0 indicates no data or data not
available)
2001 July 1 – 2002 May 25
321 329 304 311 334 316
314 345 348 316
311
291 324 0 0 268 265 258 285 279
285
227 253 294 293 270 196 194 187 211 272
0 264 254 223 270 259 245 214 255 255
289
277 259 259 234 232 233 258 283 0
0
266 206 199 205 229 185 213 192 205 214
206
199 177 246 246 200 186 170 171 169
0 0 160 168 203 154 150 198 131
124
159
231 319 311 294 260 196 230 263 222
218 0 178 192 193 183 195
175 164 156
136
149 139 144 136 152 160 144 129 125
130
157 0 142 182 203 219 313 332 310 285
295
279 175 201 219 237 285 284 248 217
0
168 192 204 227 314 324 306 288 312
312
323 347 354 337 308 305 297 231 227
196
197 286 296 291 259 233 222 204 258
310
319 325 310 282 293 304 0 271 270
283
291 276 285 285 277 267 264 275 277 275
286
288 286 280 277 280 279 0 285 289
289
289 301 294 288 290 288 286 285 287
278
270 0 269 267 254 248 252 257 259 250
258
273 277 266 265 269 0 279 294 299
291
291 284 265 271 271 265 260 271 285
303
294 290 287 286 0 270 271
270
273 275 265 248 249 260 271 263 284
296
274 251 250 265 241 247 265 0 0
261
252 245 250 271 286 312 298 275 252 284
284
302 287 303 286 272 260 277 0 0
254
247 240 265 289 324 315 322 322 306
300
335 296 266 296 334 296 294 280 0
328
303 299 295 324 290 244 263 265 292
261
238 277 245 237 272 268 280 279 0
311
268 258 276 293
Rothera provisional monthly mean total
ozone (DU)
Period Jul Aug Sep Oct Nov Dec
Jan Feb Mar Apr May Jun
2001/02 283 238 205 184 270 273 278 278 267 291
2000/01 231 230 137 168 334 294 273 278 279 278 280 276
1999/00 274 243 157 175 229 289 282 265 264 290 282 293
1998/99 288 239 159 166 252 264 270 279 267 277 300 287
1997/98
270 280 267 263
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, clouds were sighted from Rothera
on August 3, 20, 27 and September 5, 6 and 25.
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).
a)
Ozone. Ozone values at Vernadsky
generally declined from about 280 DU at the beginning of August to around 180
DU in mid October (a depletion of about 50%).
There was considerable day-to-day variation and the decline was broken
by a rise to 280 DU at the end of September.
The minimum daily mean was 146 DU on October 24. There was considerable diurnal variation in
the ozone readings at Vernadsky when the station lay under a strong
stratospheric ozone gradient. Smoothed maximum values of around 360 DU
occurred at the end of November, close to the normal time, though the maximum
daily mean value of 403 DU was on October 28.
Values generally declined from the peak at a rate of around 0.5 DU per
day, reaching a minimum of 250 DU in mid March (a depletion of over 15%).
Vernadsky preliminary mean daily total ozone (DU).
Dobson No 31: Instrument constants revised 2001 December 12
2001 August 1 – 2001 April 30
308 293 285 234 297 258 247 236 250 208
306
299 248 256 243 236 249 232 252 222
267
286 208 228 196 224 195 211 199 200 219
279
224 190 245 285 253 268 244 184 202
215
256 205 238 273 190 168 261 183 157
161
228 365 344 322 296 263 238 289 299
317
215 166 325 316 236 243 234 218 213
195
182 187 185 180 190 234 177 173 183
158
176 187 146 187 291 220 403 351 388 362
366
372 297 249 264 267 298 345 342 336
281
244 242 260 260 328 393 375 363 367
359
352 351 374 360 344 370 399 375 283
237
236 351 342 332 297 272 285 232 261
316
336 336 321 309 315 338 311 313 299
313
308 296 318 305 288 282 286 287 275 271
319
305 306 297 290 303 299 292 305 320
334
315 312 333 296 313 295 303 307 306
304
287 286 282 290 275 278 279 277 277 275
279
296 283 269 288 285 281 274 310 312
302
302 308 289 267 300 260 267 269 270
307
308 278 268 283 285 274 283
281
285 291 272 262 244 258 262 275 273
283
274 246 253 257 236 236 252 264 265
255
250 245 242 272 283 304 298 291 252 273
266
309 303 319 281 260 266 280 290 294
231
244 221 273 270 308 305 294 309 297
287
335 285 272 269 305 270 283 286 287
Vernadsky provisional monthly mean
total ozone (DU)
Period Aug Sep Oct Nov Dec Jan Feb Mar Apr Year
2001/02 245 244 233 327 299 299 286 266 283 276
2000/01 242 162 193 343 308 293 284 279 276 264
1999/00 249 189 202 283 297 292 271 262 293 260
1998/99 241 200 218 305 278 288 289 273 279 263
1997/98 261 251 235 240 297 281 266 280 281 266
1957-72 310 330 345 370 345 320 300 295 310 325
b)
Radiosonde data. The few available radiosonde flights from
Marambio, Rothera and Polarstern show that the 100 hPa temperature along the
Antarctic Peninsula was generally below the normal from mid October until
February.
c)
Nacreous clouds were sighted at Vernadsky on July 27, 28,
August 6, 10 ,13, 15, 28, 29, September 4 and October 14.
4. Information from other sources.
The use of data from TOVS satellite images from the US NCEP/NWS/NOAA Climate
Prediction Center and EP/TOMS images is acknowledged. BAS have made ozone hole movies from the TOMS images, and these
are available on our web page. They are
regularly updated. The NOAA Climate
Prediction Center gives an overview of their satellite observations for 2001 at
http://www.cpc.ncep.noaa.gov/products/stratosphere/winter_bulletins/sh_01/index.html
Further information is available on the BAS ozone web page at http://www.antarctica.ac.uk/met/jds/ozone. This contains earlier bulletins, data,
graphs and general ozone information.
It is often updated several times a week. Routine email ozone bulletins are no longer issued, but we plan
to issue one in November to provide details of the 2002 ozone hole
measurements.
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 are
reduced to the Bass-Paur scale as recommended by the WMO. The reference period used for the normals is
1957 - 1972. If you use or pass on data
in this bulletin please make acknowledgement to J D Shanklin, British Antarctic
Survey.