The Characteristics of squall line over Indonesia and its vicinity based on Himawari-8 satellite imagery and radar data interpretation

Abstract

Abstract Squall line is a rare MCS phenomenon happened in Indonesia. In these recent years, radar showed the existence of squall line pattern on 31 December 2017, 25 and 27 January 2018 in disparate spot in Indonesia. This study aims to find the common characteristic of squall lines that occurs in tropical region of Indonesia. The result shows a persistent elongated convective pattern with the trailing stratiform region extends over 100 km in more than 6 hours in all squall line events observed in this study. The average cloud top temperature below -450C indicates an abundant amount of ice crystals. Radar data analysis shows that reflectivity value and surface rainfall intensity in the core part of the squall system always higher than the outer part, with maximum reflectivity value observed on the lower level of the convective cells. Analysis of the vertical structure of squall system shows that height of convective cells on the first squall system reached 17 km, while on the second squall system reached 12 km. The origin place where the squall line formed determines the structure and character of the squall system. These findings show that updraft mechanism on the continental area is generally stronger than around marine areas.