BAMOS
12 times.( Phillpot et al., 1971). This project gave the impetus to address many remaining issues with analysis over the Southern Ocean. These charts represented the state of science at that time.
A side benefit of the GARP project was an influential paper by Zillman and Price( 1972). They derived vertical profiles of temperature and wind for a representative range of cloud categories and prepared a schematic depiction of the pattern of cloud types for an idealized mature oceanic cyclone. Crucially, they were also able to show three basic sequences of vortex development, and the evolution sequences of possible fronts. A battered photocopy of this diagram probably adorned the forecasting desks in southern forecasting offices for many years after its publication.
Zillman and Price directly address the question of how these developments fit the classical Norwegian model. In their introductory comments they note that“ the material available for the most part, is so strongly influenced by the classical Norwegian concept of an occluding Polar Front that it is usually difficult and sometimes impossible to distinguish, in retrospect, the data content from the framework of the model on which it is hung.” Their detailed diagrams of the three-dimensional structure of the mature vortex do not employ front symbols but they note, however, that this does not imply that there are no sharp temperature discontinuities. They conclude that“ any attempt to diagnostically model the cloud configuration and attendant thermal structure of even the idealised cyclone is at least as valid as, and certainly of more practical value in threedimensional analysis than, resort to the implications of some drastically over-simplified physical process such as envisaged to be operative in the formation of the classical occlusion.” They suggest that“ data-based models of this kind … may be used to supplement or replace the array of conventional frontal paraphernalia, depending upon the purpose and philosophy of the analyst.”
My first posting at the end of the Bureau’ s Meteorologist Training Course in 1980 was to the National Meteorological Analysis Centre( NMAC), where Leon Guymer, with his deep knowledge of southern hemisphere analysis, reigned as the Supervising Meteorologist. It was also the early years of the Japanese Geostationary Meteorological Satellite( GMS) with the luxury of 3-hourly visible and infrared images that reached just far enough south of Australia to be tantalising. I recall how scientific understanding, imagination and creativity came together in interpreting the satellite imagery and anchoring it to the reality of surface and balloon data from Antarctic and island stations, together with very occasional ship or buoy observations, and resulted in very convincing analysis charts. I also recall the sense of responsibility and pressure, knowing that these analyses formed the basis of increasingly reliable prognoses and forecasts on which many, aviation in particular, depended.
— Sue Barrell.
Further illumination of the complex airflow in lows came from analyses of winds along isentropic surfaces introduced by Green at al.( 1966). Browning( 1971, 1985), Harrold( 1973) and Carlson( 1980) analysed storm-relative motion fields on isentropic surfaces to understand cloud and precipitation patterns in mid-latitude cyclones. Browning introduced the term“ warm conveyor belt”. Ryan and Meadows( 1979) applied this approach to a cut-off low over Australia. Ian Bell in the Bureau’ s Training Centre made a more extensive study of the flow into fronts and lows using this approach. He gave convincing demonstrations using papier maché models in the era before sophisticated computer graphics were available, showing how the low-level air feeding into a front over eastern Australia originated in the adjacent oceans to the east rather than from the north-west.
Cold Fronts Research Program
Brian Ryan( 1982) describes how a change of focus was made leading to a renewed period of research on fronts. In Australia cold fronts research in recent decades had concentrated on interpretation of satellite imagery. In the northern hemisphere significant advances had been made both in theory, supported by numerical models, and through observational programs combining satellite and radar data, with enhanced analysis techniques. Notably, these studies had highlighted the mesoscale characteristics of fronts.
Ryan documents how the meteorological community collectively, through the Australian Branch of the Royal Meteorological Society, responded to this challenge and opportunity, with the ultimate aim of improving forecasting, particularly in local areas, on the time scale of less than 24 hours.
One recommendation arising from a two-day workshop held in 1977 was for a comprehensive study of cold fronts over southeastern Australia. That recommendation came to fruition in the Cold Fronts Research Program( CFRP)( Smith et al., 1982: Ryan et al., 1985), led by Brian Ryan, Roger Smith, Ken Wilson, John Garratt and Sandy Troup, focusing on summertime changes in south-east Australia. The CFRP had participation from two CSIRO Divisions, three universities, Bureau of Meteorology and the Australian Numerical Meteorology Research Centre. There were three field experiment phases between 1980 and 1984.
Soon after I returned to Monash University from the University of Edinburgh in 1973, a group of scientists based mainly in the Melbourne area joined together to establish the Australian Branch of the Royal Meteorological Society. The Australian Branch served amongst other things to foster collaboration between the Bureau of Meteorology, the CSIRO Divisions of Atmospheric Research and Cloud Physics and a few prominent Universities. A year or so later, as I recall, Dr. Brian Tucker, the Chief of the CSIRO Divisions of Atmospheric Research at that time, set up a meeting with representatives of these organizations to identify a few of the most important forecasting problems facing Australia that a concerted research effort by the meteorological research community might be able to make inroads towards solving. One of four areas identified was the summertime“ cool change”. It was an outcome of this meeting that the CFRP was established.