On fine structure of dot echoes as observed by acoustic sounder

Abstract

Abstract Sometimes in the lower atmospheric boundary layer, depending upon the prevailing micro-/meso-scale meteorological condition, ‘dot’ (also known as ‘lump’) type echo structures appear generally during night-time with light wind and stable stratifications. They are associated often with disturbed atmospheric boundary layer conditions like the occurrence of thunderstorms and/or of precipitation. Digitization and scanning of individual dot/lump echo structure can indicate a cluster of points with varying echo intensity levels. In the coastal region of Calcutta they are found to be spreading vertically and the size of the cluster depends on the vertical height of occurrence. Using image processing technique fine structures of these echoes have been processed, their statisticalnature has been analysed and reported in this paper.