BAMOS
6
The strongest influence on the emerging Southern Ocean analysis practice in Melbourne, as had also earlier been the case for war-time tropical analysis in Allied Headquarters in Brisbane, came from the Bureau’ s then young Supervising Meteorologist( Research) and future Director of Meteorology( 1962-1978), Bill Gibbs.
Analyses over these Southern Ocean areas inevitably required analysis of fronts. Gibbs initially was interested in applying the Norwegian model.
“ From various sources, such as the reports of the British ship“ Discovery”, I had learnt that the oceanic convergence ran roughly west-east in the vicinity of Heard Island and realised that this was a region likely to be the home of the classical polar front on which vigorous cyclogenesis was likely to occur.
“ We soon found that our expectations of cyclogenesis and frontogenesis in the Heard Island area were correct. I had many discussions with Reg Clarke, who was sceptical of the use of the polar frontal model, but Uwe Radok, after a voyage in the ANARE ship“ Tottan” in the Southern Ocean, on which he received the radio broadcasts of our analyses, confirmed that synoptic analyses based on the polar front model were consistent with the weather he encountered.
“ Our Southern Ocean analyses distributed daily to all Bureau offices and broadcast to ships at sea created a great deal of interest and debate. In the Hobart Divisional Office, Vic Bahr and Jack Langford showed particular interest in Southern Ocean analysis and Jack did much original research. Vic issued daily extended outlooks( three- and four-day forecasts) based on Southern Ocean analyses prepared in CAO and his office. These were broadcast over one of the Hobart radio stations and excited considerable public interest.
“ Vic Bahr made a special contribution in Hobart, promoting a lively image for the Bureau among Tasmanians. He also had a dynamic impact on the forecasting routine, instituting four-day outlooks. These outlooks were assisted by Jack Langford, a brilliant synoptician with the necessary skills in Southern Ocean analysis and prognosis. Vic Bahr also developed a special rapport with the French Antarctic expeditions which used Hobart as a provisioning and debriefing depot in the operation of their base in Adelie Land.”
— Bill Gibbs( 1999).
In 1952 Gibbs and other CAO staff prepared a report, published by the Antarctic Division, containing observations and synoptic charts for 1948 – 49 as well as discussion of synoptic features of the Southern Ocean and an overview of the climate as revealed by the observations.
“ The observational program at Heard and Macquarie Islands included radiosondes and pilot balloon observations and three hourly surface observations. We had a special base chart prepared extending from west of Heard Island to east of Macquarie Island and from the latitude of southern Australia to the Antarctic coastline. Apart from a few observations from passenger and cargo ships plying between South Africa and Australia, and the occasional whaler, there were no reports on our charts over the Antarctic or Southern Ocean except observations from Heard and Macquarie Islands.
“ The sparseness of observations in the Southern Ocean meant there was no point in analysing more than one chart per day. …. By plotting the three hourly surface observations … in time sequence from right to left we were able to simulate, in a general fashion, the usual movement of synoptic systems from west to east.”
— Bill Gibbs( 1999).
Meteorologists soon struggled to apply the Norwegian Cyclone Model even over the Southern Ocean which was notionally similar to the environment for which the theory had been developed. One of those who struggled with the frontal model was future Officer In Charge of the Australian Numerical Meteorology Research Centre( ANMRC), Reg Clarke. In an important paper( Clarke, 1954) he discusses the inherent difficulties in frontal analysis and includes sample charts from different analysts. He even queries the concept of a“ front”, particularly textbook warm fronts, and focuses on the crucial element of the front as a“ hyper-baroclinic zone”. His experience concurred with recent views of frontal advocates( such as Palmèn [ 1951 ]) querying the existence of a quasi-permanent polar front. Rather, they considered a“ discontinuous process, whereby cold air is injected at intervals into low latitudes behind a cold front, which dissolves on modification of the cold air, a new front appearing at higher latitudes to take its place.”
Using soundings from Perth and Kalgoorlie, Troup( 1956) addressed the controversy over the nature of the trough-line between two migratory anticyclones, which had generally been analysed as a front, at least south of the col. He tried to apply the notions of anafront and katafront, but concluded that only about half of these trough-lines could be classified as fronts. He also noted that the scarcity of warm fronts indicated that the classical occlusion model was inadequate. Sandy Troup subsequently served as CSIRO member of the analysis team of the International Antarctic Analysis Centre in Melbourne and became famous for his work on the Southern Oscillation.
Southern Ocean analysis styles continued to vary widely amongst analysts through the 1950s and 1960s notwithstanding the large increase in data during the International Geophysical Year( IGY) in 1957-8 and the more advanced analysis tools( time sections and the like) employed by the IGY Weather Central at the Little America base in Antarctica and by Henry Phillpot and his colleagues at the International Antarctic Analysis Centre( IAAC) in Melbourne in the 1960s. Some Bureau analysts with UK Meteorological Office backgrounds could not resist maintaining elaborate cold and warm front and occlusion patterns while some survivors of the Bureau post-War debates found it difficult to even include a single meridional(“ fence post”) cold front in the deep troughs extending northward from migratory Southern Ocean cyclones.
Some thoughts on frontal and upper air analysis: there were some who learned their craft in World War 2 and drew fronts like butterfly wings but having little resemblance to reality. Other drew fence post type fronts, also impossible to