Pioneer of New Zealand research in the Antarctic
Peter Macdonald
AAntarctic researcher b August 5, 1926 d September 4, 2022
blast on the ice, a spout of water rises into the air – unfortunately it all freezes into platelet ice that then falls back down to fill the hole. Peter Macdonald is using explosives to try to make a hole through the ice shelf outside Scott Base to install a sensor for his tide gauge in early 1957.
He succeeded and started recording tidal data from the start of the International Geophysical Year (IGY) period, overcoming problems with keeping the hole through the ice open through the winter and the freezing of recorders.
He started the long record of sea-level changes for McMurdo Sound (one of the longest in Antarctica), made possible by his insistence of a well-defined datum for his tide gauge measurements in 1957. He also set up the research programmes on incident and reflected solar radiation, and on sea current measurements. For observations on sunlight hours, he used the same sunlight recorder used in the 1902 Scott Expedition and recorded 24 hours of sunlight on only three days.
During the year, he also took over documenting the movement and deformation of the McMurdo ice shelf, and substantially took over the meteorological observations in mid-winter from the NZ Transantarctic Expedition (TAE).
On return to New Zealand in January 1958, results were submitted to IGY World Data Centres and reported in a Department of Scientific and Industrial Research (DSIR) Bulletin. Macdonald, who has died aged 96, authored the glaciology – ice shelf movement – report and co-authored the meteorological and sea level reports as well as a research paper on tidal and current data.
He was a member of the NZ IGY Antarctic Expedition, led by Dr Trevor Hatherton, that was part of the first wintering-over party at Scott Base, on Ross Island. The base, designed and constructed by the New Zealand government, was shared with the NZ support party for the TAE for the first year (1957), after which it was operated by DSIR as a scientific research base.
Macdonald was the last surviving member of this first wintering-over party.
William James Peter Macdonald was born in Kelburn, Wellington, and educated at Kelburn School, Wellington College, and Victoria College (later Victoria University). After the war, he secured a cadetship with DSIR and joined the geophysics section of the Geological Survey.
In 1952 he left DSIR and tried business and teaching. In late 1954 he married Doris Thorogood and started building a house. He returned to DSIR in 1956 as a successful applicant for one of five positions with the IGY Antarctic expedition in 1956-58, helping to build Scott Base.
After the IGY programme concluded, he began working on geothermal exploration in the central North Island. His contribution to exploration for, and delineation of, geothermal fields was immense.
He developed the concept of mapping the electrical conductivity of the ground to delineate geothermal fields. Ground conductivity is largely dependent upon the electrical conductivity of water in the rocks: geothermal water, hot and containing more chemicals than fresh water, has a much higher conductivity than normal groundwater, so geothermal regions will correspond to regions of higher ground conductivity.
Macdonald recognised that emerging technology allowed rapid measurements of ground conductivity to be made, leading to an ability to map the electrical conductivity of large regions. This technique facilitated the mapping of all the geothermal regions of the Taupō Volcanic Zone in central North Island.
By making hundreds of measurements across a region, it was possible to show that geothermal areas coincided with high ground conductivity areas. Drilling several holes to a depth of a kilometre in the high conductivity areas confirmed the concept when water temperatures of 200 to 300 degrees Celsius were found.
Ironically, the proof of the method came when a drill hole that was deliberately sited outside the high conductivity zone, but very close, sampled only cold water. Macdonald’s work was accepted thereafter without question. This mapping technique became the international standard.
In 1969, he was seconded to the UN Development Programme to do geothermal exploration work in Chile, at an altitude of 4300m, for five months. Subsequently, he continued to fit in further geothermal consultancies in El
Salvador, Chile, the Philippines, Vanuatu and Canada.
Probably his greatest success was in the Philippines, where he saved the NZ MAF-funded aid programme on Leyte. Before he became fully involved, seven holes had been drilled without a single success and abandoning the prospect was being considered. Based on conductivity measurements, Macdonald changed the focus of the exploration and sited the first successful well of what became a 500+ megawatt development.
At the end of 1988, Macdonald retired from DSIR, having completed 40 years’ service. He was the author of 14 published scientific papers in New Zealand and overseas journals (eight on Antarctica, and three in Nature), and 39 Conference Proceedings and DSIR reports.
He returned to Scott Base in late January 2000 as part of the millennium trip that saw 11 of the original winteringover party return for three days.
A few years ago, he and Doris endowed a prize at Massey University, and he recently endowed an award at Victoria University of Wellington.
His contribution to the development of geothermal resources, both in New Zealand and overseas, is his lasting legacy to science. He will be remembered for both his scientific influence and his practical, generous and encouraging spirit.