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|Title:||Mesospheric backscatter echoes as observed by the Indian MST Radar Facility at Gadanki|
|Authors:||Chakravarty, S C|
|Keywords:||MST radar;Mesospheric backscatter;Backscatter echoes|
|Abstract:||The Indian Mesosphere Stratosphere Troposphere (MST) radar facility at Gadanki (13.5ºN, 79.2ºE) has been utilised to characterise the mesospheric backscattered signals by considering already available results and new analysis of past and recent data sets. Individual days data as well as continuous and long term Common Mode Observation (CMO) data have been used to study (1) the basic features of mesospheric return echoes, (2) scattering layer heights, (3) relation to mesospheric turbulence governed through weather phenomena, (4) spatial and temporal variability, (5) seasonal patterns and, (6) inter-annual changes. While the present results have been found to be consistent, with the earlier results, some new aspects have been brought out. A broad theoretical background is provided relevant to turbulent scattering of radar waves so that the results are interpreted from this perspective. The main results of the mesospheric studies with the Gadanki radar include the very intermittent nature of echoes varying with radar beam directions and time. Temporal variations of the radar returned signals are found to be related to the growth and decay of eddies, generated by atmospheric turbulence. The mean height of mesospheric scattering layer is around 72 km and the life period of the turbulence patches generally lies in the range 10-20 min. In the months of June-July and September-October of 2003, the intensity of radar returned signals were stronger compared to other months and there is an elevation of the mean scattering layer by ~2 km with the decrease in solar activity between 2003 and 2005.|
|ISSN:||0975-105X (Online); 0367-8393 (Print)|
|Appears in Collections:||IJRSP Vol.36(6) [December 2007]|
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