Tropospheric disturbance of 17–21 December 1974 and its effect on microwave propagation

• DOI: 10.1007/bf00221827
• Publication Date: 2004-09-18T07:40:53Z
• Authors: A. P. Mitra; Y. V. Somayajulu; S. P. Singal; S. C. Majumdar; T. R. Tyagi; B. M. Reddy; S. K. Agarwal; B. S. Gera; A. B. Ghosh; S. K. Sarkar
• Keywords: SODAR

A number of troposphere-monitoring experiments were pressed into service during a large tropospheric disturbance which lasted for several days in December 1974. The experiments operated intensively included a monostatic Sodar system, a satellite radio beacon receiver at very low elevation angles, Meteorological Radiosondes, a 250-kW weather radar, a microwave LOS link and a microbarograph. This multi-pronged campaign yielded very useful results and the correspondences between various observations were striking. The Sodar and microwave link observations were visibly affected only when δN reached a value of about −70 units; however, the satellite beacon observations showed anomalous behaviour even for lower δN values. Rather spectacular coincidences occurred on one night: the large fading (up to 10 db) in the LOS link; highly disturbed conditions displayed in the entire Sodar range; the largest tropospheric effect on the satellite beacon system; and the most active superrefraction of the radar echoes. It was also noticed that these effects are obvious only during nights, while they remain masked or dampened in the sun-lit hours.