Radiophysics, 1962 to 1990 Iain Reid Bronwyn Dolman Space and - PowerPoint PPT Presentation

Radiophysics, 1962 to 1990 Iain Reid Bronwyn Dolman Space and Atmospheric Physics Group

Location of Buckland Park and St Kilda Field Stations Buckland Park St Kilda Adelaide The St. Kilda site is about 22 km north of Adelaide and about 3 km from the coast. It was operational in November 1959 and continued to be used for about 20 years.

The atmosphere and near space environment

Some pre-History • JJ Thompson supervised Ernest Rutherford. • Thompson and Rutherford supervised E.V. Appleton. • All three won Noble Prizes • Appleton supervised JA Ratcliffe

Some pre-History JA Ratcliffe, FRS Some of his students • Henry Booker • Sidney Bowhill • Ronald Bracewell (Aus) • Basil Briggs • J.L. Pawsey (Aus) • Frederick White (NZ) • David Whitehead • 1927 to 1939 and 1946 to 1960 Cavendish Lab, Cambridge (regarded as number two to Bragg in the latter period) • Telecommunications Research Establishment (TRE) during WWII • 1960 to 1966 he was Director of the Radio & Space Research Station at Slough

AP Rowe LGH Huxley • • Director of the TRE, 1938-45 Radar Research School, TRE • • VC UoA, 1948-58 Elder Chair of Physics, UoA, 1949-60 • VC ANU, 1960- 67 “Huxley found …. a department starved as a result of When he arrived in 1948, “The the war of both resources and opportunities to appoint ample buildings housed uneven new personnel”, but “…he had the advantage of being resources, with Engineering well able to expand his department rapidly as a equipped and Physics a junk- consequence of swelling student numbers”, and shop”, If the Gown Fits, 1960 “…support from an enthusiastic and energetic Vice- chancellor….These years also coincided with the introduction of Ph.D. courses throughout Australia”, Compton, Historical Records of Australian Science, Volume 8, Number 4.

Graham Elford and Basil Briggs WG Elford BH Briggs Adelaide (BSc(Hons), 1949; Ph.D. 1955). Cambridge (B.A. 1942; Ph.D. 1952; DSc). University of Adelaide, 1950 to 1980’s Junior Scientific Officer, TRE, 1942 to 1946. Radio Research Group, Cavendish Laboratory, 1946 to 1961 University of Adelaide, 1962 to 1988

Meteor Physics to Radiophysics • Graham Elford joined the department in 1950 and led the development in Meteor physics • Basil Briggs joined the department in 1962, and the group then effectively became a Radiophysics research group under Graham and Basil, encompassing a broad range of activities. • This name continued to be used until the mid- 1980’s, when the Atmospheric Physics name was adopted  Upper Atmosphere Group 1962 Back row : R. Roper, J. Welsby, C. Nilsson, A. Bastian, B. Stone. Front row : Dr. E. Murray, Miss J. Allister, Miss M. Chapman, Dr. G. Elford  The group is currently classified 80% Space and 20% Atmospheric for the ERA, and the group name is now Space and Atmospheric Physics

“ Radiophysics ” in the 1960’s • Meteor physics • Radio astronomy • Atmospheric scattering of laser light • Ionospheric physics

“Radiophysics” in the 1970’s Group members and research topics

Meteor Physics 1950 Basis of the Adelaide Meteor Wind System constructed December 1951 The first photographic recordings of meteor echoes showing 'Doppler beats' obtained during the Geminid shower. Full system operation  measurement of June 1952 atmospheric motion within the height range 75-105 km, by observing the drift of meteor trails; photographic recording, manual analysis March 1955 System operation ceases December 1956 Mawson Station meteor radiant system established, continues to operate intermittently until 1959 Meteor echo recorded in December 1952. The ‘spikes’ on the upper two Doppler beat signals delineate a phantom record displaced 1958 St Kilda field site established in phase by 90º before or after the main traces dependant on the sign of the Doppler signal. 1969-72 Buckland Park MF meteor studies The centre pairs of traces determine the Mid-1970s Meteor work at St Kilda ceases direction of arrival of the sky wave. The range is determined from a display at the bottom of Early-1990s Meteor work resumes on the BP ST VHF radar the record. The range markers are at 10 mile intervals with the uppermost dotted line set at Late 1990s Meteor radar work ‘re - born’ with advent of small 10 miles. pulsed VHF radar systems (Table modified after Elford, 1994, 2011)

Radio astronomy • In 1968 Paul Dennison joined the group from Cambridge • Facilities for radioastronomy were developed at BP and two outstations to enable observations to be carried out at two frequencies, 111.5 and 236 MHz • A large antenna array comprising 4 parallel E-W corner reflectors with a total collecting area of about 2500 m 2 was constructed at BP

Radio astronomy • Two other arrays, of half that size were constructed at Burra and Kadina, forming a triangle with sides of lengths approximately 100 km. • Using this arrangement of three spaced sites interplanetary scintillation of radio sources were studied in order to derive various parameters of the solar wind, velocity, irregularity size etc., [e.g., Dennison and Hewish, 1967] and angular structure of radio sources [e.g., Little and Hewish, 1968] • Dennison resigned from the University in 1973

Laser radar (lidar) • Work initiated by Graham Elford and continued from 1963 until 1980. Karel Bartusek, David Gambling and Stuart Young completed PhD theses in this area. • Fred Jacka of the Mawson Institute for Antarctic Research restarted lidar work in the late 1980’s, and measurements were made at BP between March 1992 and May 1993 by Stephen Argall. • The descendent of the Mawson lidar operates at Davis Station in the Antarctic, and a new system is under development at BP (Bottom right)

Ionospheric Physics

Ionospheric Physics The Large MF/HF array Graham Elford and Basil Briggs with a model the large MF/HF antenna array

Buckland Park MF/HF Array

Complete receiving system for the MF radar D-region partial reflection echo from a single receiver displayed on a CRO Snapshot in time of the amplitude of the backscatter diffraction pattern at the ground. The ground diffraction pattern is the Fourier Transform of the angular polar diagram of the backscattered radio signal (After Briggs, 1984)

Spaced Antenna Technique Snapshot of the intensity of the electric field strength on the ground formed by the backscattered radio wave (After MacKinnon, 2001) Correlation analysis (After Briggs, 1984)

Spaced Antenna Technique This snapshot is part of a movie of the changing intensity of the ground diffraction pattern produced by the backscattered radio wave on the ground. It was produced by separately driving 89 light bulbs by 89 receivers connected to 89 antennas within the array. A diffusor of ground glass was placed Correlation analysis between the light bulbs and the camera. (After Briggs, 1984)

Ultrasonic Image forming Snapshot of ground diffraction pattern from the F- region (left) and its focussed image (right) The photograph on the left shows Nigel Holmes (left) and Basil Briggs (right) in front of the ultrasonic image forming system. The schematic diagram on the right shows the principle of operation. Snapshot of the focussed image of the ground diffraction pattern from the E-region

Bob Vincent RA Vincent Research • D-region winds, turbulence and gravity wave studies • MF radar network • VHF ST radar • VHF Boundary layer radar • Radiosonde winds, energy and momentum fluxes in the Canterbury, (BSc(Hons), 1964; Ph.D. 1967). troposphere and stratosphere Senior Teaching Fellow, 1970 to 1973 • Stratospheric super-pressure University of Adelaide, 1973 to 2011 balloons

Upper atmosphere

1985: VHF Stratospheric Tropospheric (ST) Radar – the first in the Southern Hemisphere

ST Radar

Wayne Hocking WK Hocking Research • D-region turbulence studies Adelaide, (BSc(Hons), 1976; Ph.D. 1982). University of Adelaide, late 1980s to early 1990s

Dual-Beam Radar Technique: Vincent and Reid (1983) w  ,    u u w v w This work established a technique to verify the central role of gravity Radar wave breaking in establishing the Radar beam beam dynamical and temperature 1 2 structure of the upper atmosphere, and then verified it. Summer Winter     2 2 v ( , R ) v ( , R )    1 2 ( ) u w z  2 sin 2   1 ( ' ' ) u w   F   z

Iain Reid IM Reid Research • D-region winds, temperatures, electron densities and gravity wave studies • The high latitude upper atmosphere • Meteor radar • ST radar • Boundary layer radar • Radar development • Optical studies of the Mesosphere Lower Thermosphere region Adelaide, (BSc(Hons), 1979; PhD, 1985; DSc, • 2008). Lidar University of Adelaide, 1988 to present

Summary • Work commenced by Basil, Graham, Fred Jacka and Bob continues in some form and is still leading edge • The BP MF/HF large array continues to be a first rate and unique instrument 45 years after it was completed