24
BAMOS Dec 2024
Dick Jenssen and the first Numerical Weather Prediction computation in Australia
Obituary
Terry Hart , AMOS History Group
An Australian pioneer in meteorology and glaciology , Martin James Ditmar ( Dick ) Jenssen , passed away on 7 March at the age of 88 . Tributes noted him as a computer pioneer and founding member of the Melbourne Science Fiction Club in 1952 , keenly interested in classical music and having a fierce and playful intellect . Former colleagues recalled him as a lovely gentle person , always easy to get along with and a friendly willing collaborator .
After three years from 1963 as an Assistant Professor in the Meteorology Department at the University of Wisconsin , Madison , he spent most of his professional life as a Senior Lecturer in the Department of Meteorology at the University of Melbourne , including some time as the Chair of the Department , before taking early retirement in 1992 .
He was a very important influence in the early days of Numerical Weather Prediction ( NWP ) development in the Bureau and later switched to glaciology where he made significant contributions in the modelling of glacial dynamics and the thermodynamics of Antarctica . He created weather-education software to run on the very earliest PCs .
Dick Jenssen carried out the first demonstration in Australia of what is known as NWP . His experiments using the CSIRAC computer were described in his 1959 M . Sc . thesis , carried out under the supervision of Uwe Radok . Bill Bourke has described this pioneering achievement in a paper published in the Proceedings of the Royal Society of Victoria in December 2021 . His account is based not only on written records but on personal discussions and communications with Dick in recent years .
Dick ’ s MSc thesis was not published and Bill ’ s paper notes that while Dick ’ s studies are mentioned in references to the history of NWP in Australia , little is known of the pioneering scope of Dick ’ s work . Bill aimed to present an account of these studies – both the NWP and the computational aspects .
There was a brief record of Dick ’ s work in a summary in the Australian Meteorological Magazine of a colloquium given by Uwe Radok at the University of Melbourne in October 1958 . A brief extract from that summary states :
“ The limited capacity of the CSIRAC computer made it necessary to break down the procedure into half a dozen separate steps , each of which has to be explained anew to the machine for every time step by a series of commands , a “ program ”. These programs were designed by Mr . D . Jenssen , a research assistant in the University Meteorology Department who demonstrated their execution by the machine during the colloquium . Mr
Jenssen also showed how the machine can be made to print directly the approximate contour lines of the forecast chart at the end of the calculation . “
The computer had originally been developed by Trevor Pearcey and Maston Beard in the CSIRO Division of Radiophysics in Sydney and made its first computations in 1949 . It was among the very first computers in the world with stored programs and had other innovative features devised by Trevor Pearcey . The computer was relocated to the University of Melbourne in 1955 when CSIRO decided to give priority to other research areas .
Dick Jenssen , at the reassembled CSIRAC computer in 1999 , recapturing a photo published in a Melbourne newspaper in September 1958 . Photo courtesy of Peter Thorne
Bill provided details of Dick ’ s innovative work :
• the selection and formulation of the equations used to represent the atmosphere over the Australian region ,
• selecting the appropriate numerical techniques to solve the equations ,
• optimizing the use of the CSIRAC computer and the novel stored program capability , coping with the very limited memory ( 640 words ) and developing a form of visualization of the results .