IHSibWdOO dVW A13I0OS OI10UV1NV QNVTV3Z AA3N umooT VNUN30UV UjUEN UBS IBJ3U3D H sonvisi 3tiH3 ie|ewE3 aiusjuai gi xn BJ3l|l0U 21 QNV113HS >in tepeJBJ H vsn jOLU|ed 01 Hinos vNiiNiouv oiqttiBJBW ojopoiuoo as;A 6 3NUN30UV ezueudsj 9 3iiH3 stflOOjH.O opjetuag lejsuag / Sims ibjj ojnuv ueijdeo g vnimo ||BW K8J9 assn u9SnEHS6ui|i9g 31IMD gSJCW OJIOPOH 31U9IU31 9 Avnonun seBiUV V VNUN30UV Aueqnp siuaiuai £ CWTOd »|SM0)3JV &U3H 2 11ZVUS 7B1J3J 3iuepu«uj03 I VinSNINBd 3I13UV1NV OIOHVINV ANTARCTIC (successor to "Antarctic News Bulletin) Vol. 11 No. 6 Winter 1987 Issue 126 Contents Polar Activities Special report 234 ANTARCTIC is published quarterly by the New Zealand 238 New Zealand Antarctic Society Inc., 1978. Australia 244 244 ISSN 0003-5327 Bulgaria Italy 245 Editor: Robin Ormerod Japan 247 Please address all editorial inquiries, con South Korea 248 tributions etc. to the Editor, P.O. Box 2110, United Kingdom 249 Wellington, New Zealand. United States 252 Telephone: (04) 791-226 International: + 64-4-791-226 Sub-Antarctic Deadline for final copy for the spring 1987 Macquarie 261 issue is February 20. Snares 263 Publication date March 18. All administrative enquiries should go to General Bulletin "Co-ordinator", P.O. Box 1223, Greenpeace 264 Christchurch. Scott-Amundsen descendants 266 Erebus chalice 267 Registered at P.O. Headquarters, as a magazine. Obituaries 268 Book review 270 Cover: Dobson units represent an amount of ozone equivalent to an 0.01mm thick layer at surface pressure. This colour © No part of this publication may be reproduced enhanced version was based on readings in any way without the prior permission of the taken by Nimbus 7 on October 7, 1987. publishers. Reproduced with permission from the Na tional Aeronautics and Space Agency. Washington. Story page 234. Antarctic Winter, 1987 Special report: Ozone: the hole that is not a hole Preliminary results from this year's spring ozone measurements made during a series of flights by U.S. scientists in September and October 1987 show the layer of ozone in the stratosphere over Antarctica to be the most depleted on record; 15 percent less than the previous minimum of September 1985. In an effort to explain the causes of the depletion further ground based exploratory work is being undertaken by New Zealand and U.S. scientists throughout the season. (This article summarises some of these efforts. "Antarctic" would like to thank Dr Tom Clarkson of the New Zealand Meteorological Service and Gordon Keys and Nicholas Jones of PEL, Lauder for their assistance.) Ozone is a relatively rare form of oxygen coming as high as 50 per cent during comprising three atoms of oxygen in each spring in the last three years. molecule instead of two. It is formed by Current photochemical models did not the action of sunlight on oxygen at predict a depletion of this magnitude and altitudes of 30 to 50 km and some of it is they cannot explain the decrease. Scien simultaneously destroyed by sunlight and tists seeking an explanation are concen by complex and coupled catalytic reactions trating chiefly on the unusual meteorology involving mainly the oxides of hydrogen, over the continent during the winter and nitrogen and chlorine in approximately spring and associated atmsopheric chem equal amounts. Because energy is absorb istry. ed in the stratosphere by the ozone its distribution modifies the stratospheric The ozone is threatened globally by the radiation balance and determines the ver increasing use of a range of tical temperature structure. Below 25 km chloroflurocarbon compounds which solar ultra violet has less influence on have enormous utility as refrigerants, ozone production and loss as it is absorbed plastic foaming agents, aerosol pro- by the ozone above. pellants. cleaning solvents and fire ex Ozone is important because of its ability tinguishers. The Antarctic ozone hole to filter out the sun's ultraviolet radiation. phenomenon has been a spur to some Scientists are concerned that if the area of remarkable international co-operation depletion should spread it will result in in under the auspices of UNEP. In Sep creased occurrence of skin cancer and tember 1987, the Montreal Protocol unknown changes in animal and plant life. was signed by 24 countries (with many more expected to join). This is an Antarctic monitoring agreement for governments to ensure Monitored from Antarctica since 1957, that the use of fluorocarbons is reduced spring time (August to November) by 50 percent during the next ten decreases in atmospheric/stratospheric years. This is probably not enough to ozone have been observed from Halley completely stop ozone depletion but is Bay, Syowa and South Pole Stations since nevertheless a move in the right direc the late 1970's and have been recorded by tion and a clear signal to industry to satellites over a wider area of the conti develop alternatives to avoid being nent. Depletion has been estimated as be caught with a dying technology. 234 Winter, 1987 Antarctic Antarctica is susceptible to abnormal chemistry because of a unique vortex or "self con tained" winter weather pattern in which the air in the strato sphere above the continent re ceives very little influx from warmer latitudes. Almost cyclonic in nature it is charac terised by strong horizontal temperature gradients. The stable pattern, which isolates the polar regions from more equatorial areas, persists late into spring and is unlike the northern hemispheric polar c o n d i t i o n s w h i c h a r e fragmented earlier by global scale wave motions. At the centre of the vortex temperatures fall as low as -85 degrees C — lower than any where else in the stratosphere — and remain low until well into spring. After months of darkness sunlight gradually returns in August modifying the atmospheric chemical compounds by photolysis. Several explanations of ozone depletion relating to the chemistry of the stratosphere assume that even in these conditions concentrations of other compounds in the at mosphere would change along with the concentration of ozone; verification of such hypotheses requires atmospheric chemical The New Zealand Meteorological Service's Dob data which can only be obtained during son Spectrophotometer as installed in the small the Antarctic spring. laboratory at Arrival Heights. Photo Tom Clarkson Early information Much of this season's early information samples and measuring concentrations of was gathered in a series of flights made by various chemicals in the atmosphere. two NASA aircraft flying out of Southern The other aircraft, a modified DC8, car Chile. A ER2, or civilian variant of the U2 ried out seven experiments using remote spy plane, made 12 sorties into the so- sensing devices to measure ozone concen called "hole" over Antarctica at altitudes trations at a distance from the aircraft using of up to 20,700 meters as part of 14 ex sunlight, moonlight or laser reflections. periments involving the collection of air Operating at a lower altitude and longer Antarctic Winter, 1987 range it made 13 flights to the South Pole of reactive nitrogen and reactive chlorine and landed in Christchurch on the final species. sortie. The whole airborne experiment in In support of NOZE 1 in 1987 scientists volved over 160 scientists, pilots and other sought to obtain infrared solar spectra from personnel and cost an estimated $US10 ground based stations at the South Pole. million. These spectra contain thousands of ab NOZE1 sorption lines produced by compounds present in the atmospheric chemistry at the In 1986/87 American scientists par time measurements from the aircraft, in ticipating in the first spring National Ozone volved in the project, were made. Because Expedition (NOZE 1) measured as many the instruments respond to molecules any stratospheric chemical constituents as where along the optical path, the tech possible to obtain a better understanding of nique yields information on the total col chemical and dynamic processes that may umn density of compounds present in the contribute to the decrease in ozone. stratosphere. Preliminary results of the 86-87 expedi Working at Arrival Heights from late tion confirmed that nitrogen oxides were August until mid-October the same team of present in the small amounts described by scientists within NOZE 2 were joined by New Zealand's DSIR group from Lauder* New Zealander Nicholas Jones from who, in 1982, initiated a continuing pro Lauder. Using the same instrument as in gramme of measurements of nitrogen ox the previous year the team took measure ide, ozone and oxides of chlorine from Ar ments which would subsequently be rival Heights. The New Zealanders' year round ground based visible and ultra-violet spectrometry results have now also been BAS studies supplemented by data from the Pole and Measurements of the total ozone content Halley Bay adding a spatial dimension to of the atmosphere are made at the BAS the results. observatories. NASA has collaborated with Chlorine BAS by providing ozone-sondes flown Chlorine compounds were also found by from Faraday in order to make compari the American scientists to be more sons with satellite observations. Since ozone acts as a shield filtering out harmful prevalent. These results support chemical theories suggesting that chlorine or chlo ultraviolet radiation from the sun, a rine-bromine chemical mechanisms are af decrease in the ozone layer would be of fecting the level of ozone in the strato considerable concern. Recent studies have sphere. shown that in the last decade or so there Some 1986/87 data indicated that the has been a 30% reduction in the ozone abundance of ozone-destroying chlorine amount at Halley in spring. This could be compounds was about 20 to 50 times attributed to chlorine released from man- greater than anticipated and they vary made chlorofluorocarbons used as aerosol diurnally.