Anomalous microwave propagation study using multistation cyclone warning radars in the Indian east coast

Abstract

Steep changes in the meteorological conditions particularly in the coastal regions usually cause anomalous propagation of microwaves and seriously affect the performance of radars and other microwave communication systems situated over there. For better understanding of propagation mechanism of microwaves, a campaign was conducted during the month of May 1982 in which S-band, pulsed cyclone warning meterorologicla radars situated at Karaikal, Madras, and Machilipatnam in the Indian east coast were used for studying the occurrence of superrefraction and ducting. The above study of long distance anomalous microwave propagation indicates that the superrefraction and ducting conditions all along the coast of the Bay of Bengal are not identical. The analysis of radiosonde data corresponding to the same period of radar observations from these three stations showed that refractivity gradients do not always correlate with the occurrence of superrefraction or ducting conditions. It is noted that land and sea breezes were closely associated with the occurrence of superrefraction and ducting and the latter was more marked when light winds were easterly, south-easterly or south-westerly.