A study of reception of Omega transmissions by the Navaid sounding instrumentation on Indian Monex ships during Monex-79

Abstract

During the global weather experiment and Monex-79 upper air observations were made over the Arabian Sea and the Bay of Bengal using for the first time the FGGE Navaid sounding systems. Two such complete Navaid systems were installed on board Indian Monex ships. These ships were deployed in the central and south Arabian Sea during May-June 1979 and in the Bay of Bengal during July 1979. In addition to this a data acquisition module of the Navaid system was fitted in the, third Monex ship which was located in the south and central Bay of Bengal during May-July 1979. The three ships made 284 upper air ascents in all. The Navaid sounding technique and instrumentation proved their usefulness for upper wind measurements over sea areas from ocean platforms. A brief description of the Navaid instrumentation and the expendable Omegasonde used are given.

In this report an evaluation of reception pattern of the worldwide Omega transmissions obtained at the systems installed on board the Indian Monex ships over the Arabian Sea and Bay of Bengal during Monex-79 (May-July 79) is also presented. The Navaid instrumentation could receive Omega signals from a larger number of worldwide Omega stations over the Arabian Sea than the Bay of Bengal during Monex-79. Omega signals at least from three or more Omega stations were always received enabling the monex ships to be within the great circle triangle formation of combination of three Omega stations, thereby yie1ding a reliable upper wind data set over the sea areas in Monex-79.